192 files changed, 8933 insertions, 1984 deletions

diff --git a/gl/m4/00gnulib.m4 b/gl/m4/00gnulib.m4
index 7fe03e0b..2b205b35 100644
--- a/gl/m4/00gnulib.m4
+++ b/gl/m4/00gnulib.m4
@@ -1,8 +1,10 @@
-# 00gnulib.m4 serial 8
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# 00gnulib.m4
+# serial 9
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl This file must be named something that sorts before all other
 dnl gnulib-provided .m4 files.  It is needed until the clang fix has
@@ -49,14 +51,14 @@ dnl AC_REQUIRE([gl_COMPILER_CLANG])
     [if test $gl_cv_compiler_clang = yes; then
        dnl Test whether the compiler supports the option
        dnl '-Werror=implicit-function-declaration'.
-       save_ac_compile="$ac_compile"
+       saved_ac_compile="$ac_compile"
        ac_compile="$ac_compile -Werror=implicit-function-declaration"
        dnl Use _AC_COMPILE_IFELSE instead of AC_COMPILE_IFELSE, to avoid a
        dnl warning "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".
        _AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]],[[]])],
          [gl_cv_compiler_check_decl_option='-Werror=implicit-function-declaration'],
          [gl_cv_compiler_check_decl_option=none])
-       ac_compile="$save_ac_compile"
+       ac_compile="$saved_ac_compile"
      else
        gl_cv_compiler_check_decl_option=none
      fi
@@ -71,11 +73,11 @@ dnl Redefine _AC_CHECK_DECL_BODY so that it references ac_compile_for_check_decl
 dnl instead of ac_compile.  If, for whatever reason, the override of AC_PROG_CC
 dnl in zzgnulib.m4 is inactive, use the original ac_compile.
 m4_define([_AC_CHECK_DECL_BODY],
-[  ac_save_ac_compile="$ac_compile"
+[  ac_saved_ac_compile="$ac_compile"
   if test -n "$ac_compile_for_check_decl"; then
     ac_compile="$ac_compile_for_check_decl"
   fi]
-m4_defn([_AC_CHECK_DECL_BODY])[  ac_compile="$ac_save_ac_compile"
+m4_defn([_AC_CHECK_DECL_BODY])[  ac_compile="$ac_saved_ac_compile"
 ])
 
 # gl_00GNULIB
diff --git a/gl/m4/__inline.m4 b/gl/m4/__inline.m4
index acf8668b..d1b8257b 100644
--- a/gl/m4/__inline.m4
+++ b/gl/m4/__inline.m4
@@ -1,8 +1,12 @@
-# Test for __inline keyword
-dnl Copyright 2017-2023 Free Software Foundation, Inc.
+# __inline.m4
+# serial 1
+dnl Copyright 2017-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+# Test for __inline keyword
 
 AC_DEFUN([gl___INLINE],
 [
diff --git a/gl/m4/absolute-header.m4 b/gl/m4/absolute-header.m4
index e7947648..5501b07b 100644
--- a/gl/m4/absolute-header.m4
+++ b/gl/m4/absolute-header.m4
@@ -1,8 +1,10 @@
-# absolute-header.m4 serial 17
-dnl Copyright (C) 2006-2023 Free Software Foundation, Inc.
+# absolute-header.m4
+# serial 18
+dnl Copyright (C) 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Derek Price.
 
@@ -66,7 +68,7 @@ AC_DEFUN([gl_ABSOLUTE_HEADER_ONE],
   esac
 changequote(,)
   case "$host_os" in
-    mingw*)
+    mingw* | windows*)
       dnl For the sake of native Windows compilers (excluding gcc),
       dnl treat backslash as a directory separator, like /.
       dnl Actually, these compilers use a double-backslash as
diff --git a/gl/m4/af_alg.m4 b/gl/m4/af_alg.m4
index f4c0d624..38575b6d 100644
--- a/gl/m4/af_alg.m4
+++ b/gl/m4/af_alg.m4
@@ -1,8 +1,10 @@
-# af_alg.m4 serial 6
-dnl Copyright 2018-2023 Free Software Foundation, Inc.
+# af_alg.m4
+# serial 6
+dnl Copyright 2018-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Matteo Croce.
 
diff --git a/gl/m4/alloca.m4 b/gl/m4/alloca.m4
index c685fac9..68fc6211 100644
--- a/gl/m4/alloca.m4
+++ b/gl/m4/alloca.m4
@@ -1,9 +1,11 @@
-# alloca.m4 serial 21
-dnl Copyright (C) 2002-2004, 2006-2007, 2009-2023 Free Software Foundation,
+# alloca.m4
+# serial 21
+dnl Copyright (C) 2002-2004, 2006-2007, 2009-2025 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_ALLOCA],
 [
diff --git a/gl/m4/arpa_inet_h.m4 b/gl/m4/arpa_inet_h.m4
index fa5fe831..5dae6f72 100644
--- a/gl/m4/arpa_inet_h.m4
+++ b/gl/m4/arpa_inet_h.m4
@@ -1,8 +1,10 @@
-# arpa_inet_h.m4 serial 17
-dnl Copyright (C) 2006, 2008-2023 Free Software Foundation, Inc.
+# arpa_inet_h.m4
+# serial 18
+dnl Copyright (C) 2006, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Written by Simon Josefsson and Bruno Haible
 
@@ -67,8 +69,12 @@ AC_DEFUN([gl_ARPA_INET_H_REQUIRE_DEFAULTS],
 AC_DEFUN([gl_ARPA_INET_H_DEFAULTS],
 [
   dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_DECL_HTONL=1;      AC_SUBST([HAVE_DECL_HTONL])
+  HAVE_DECL_HTONS=1;      AC_SUBST([HAVE_DECL_HTONS])
   HAVE_DECL_INET_NTOP=1;  AC_SUBST([HAVE_DECL_INET_NTOP])
   HAVE_DECL_INET_PTON=1;  AC_SUBST([HAVE_DECL_INET_PTON])
+  HAVE_DECL_NTOHL=1;      AC_SUBST([HAVE_DECL_NTOHL])
+  HAVE_DECL_NTOHS=1;      AC_SUBST([HAVE_DECL_NTOHS])
   REPLACE_INET_NTOP=0;    AC_SUBST([REPLACE_INET_NTOP])
   REPLACE_INET_PTON=0;    AC_SUBST([REPLACE_INET_PTON])
 ])
diff --git a/gl/m4/assert_h.m4 b/gl/m4/assert_h.m4
index abba4fa3..e77524ca 100644
--- a/gl/m4/assert_h.m4
+++ b/gl/m4/assert_h.m4
@@ -1,40 +1,43 @@
-# assert-h.m4
-dnl Copyright (C) 2011-2023 Free Software Foundation, Inc.
+# assert_h.m4
+# serial 5
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Paul Eggert.
 
 AC_DEFUN([gl_ASSERT_H],
 [
   AC_CACHE_CHECK([for static_assert], [gl_cv_static_assert],
-    [gl_save_CFLAGS=$CFLAGS
+    [gl_saved_CFLAGS=$CFLAGS
      for gl_working in "yes, a keyword" "yes, an <assert.h> macro"; do
-      AS_CASE([$gl_working],
-        [*assert.h*], [CFLAGS="$gl_save_CFLAGS -DINCLUDE_ASSERT_H"])
-
-      AC_COMPILE_IFELSE(
-       [AC_LANG_PROGRAM(
-          [[#if defined __clang__ && __STDC_VERSION__ < 202311
-             #pragma clang diagnostic error "-Wc2x-extensions"
-             #pragma clang diagnostic error "-Wc++17-extensions"
-            #endif
-            #ifdef INCLUDE_ASSERT_H
-             #include <assert.h>
-            #endif
-            static_assert (2 + 2 == 4, "arithmetic does not work");
-            static_assert (2 + 2 == 4);
-          ]],
-          [[
-            static_assert (sizeof (char) == 1, "sizeof does not work");
-            static_assert (sizeof (char) == 1);
-          ]])],
-       [gl_cv_static_assert=$gl_working],
-       [gl_cv_static_assert=no])
-      CFLAGS=$gl_save_CFLAGS
-      test "$gl_cv_static_assert" != no && break
-     done])
+       AS_CASE([$gl_working],
+         [*assert.h*], [CFLAGS="$gl_saved_CFLAGS -DINCLUDE_ASSERT_H"])
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#if defined __clang__ && __STDC_VERSION__ < 202311
+               #pragma clang diagnostic error "-Wc2x-extensions"
+               #pragma clang diagnostic error "-Wc++1z-extensions"
+              #endif
+              #ifdef INCLUDE_ASSERT_H
+               #include <assert.h>
+              #endif
+              static_assert (2 + 2 == 4, "arithmetic does not work");
+              static_assert (2 + 2 == 4);
+            ]],
+            [[
+              static_assert (sizeof (char) == 1, "sizeof does not work");
+              static_assert (sizeof (char) == 1);
+            ]])
+         ],
+         [gl_cv_static_assert=$gl_working],
+         [gl_cv_static_assert=no])
+       CFLAGS=$gl_saved_CFLAGS
+       test "$gl_cv_static_assert" != no && break
+     done
+    ])
 
   GL_GENERATE_ASSERT_H=false
   AS_CASE([$gl_cv_static_assert],
@@ -46,20 +49,42 @@ AC_DEFUN([gl_ASSERT_H],
        gl_NEXT_HEADERS([assert.h])])
 
   dnl The "zz" puts this toward config.h's end, to avoid potential
-  dnl collisions with other definitions.  #undef assert so that
-  dnl programs are not tempted to use it without specifically
-  dnl including assert.h.  Break the #undef apart with a comment
-  dnl so that 'configure' does not comment it out.
+  dnl collisions with other definitions.
+  dnl Hardcode the known configuration results for GCC and clang, so that
+  dnl a configuration made with the C compiler works also with the C++ compiler
+  dnl and vice versa.
+  dnl The seemingly redundant parentheses are necessary for MSVC 14.
+  dnl #undef assert so that programs are not tempted to use it without
+  dnl specifically including assert.h.
+  dnl #undef __ASSERT_H__ so that on IRIX, when programs later include
+  dnl <assert.h>, this include actually defines assert.
+  dnl Break the #undef_s apart with a comment so that 'configure' does
+  dnl not comment them out.
   AH_VERBATIM([zzstatic_assert],
-[#if (!defined HAVE_C_STATIC_ASSERT && !defined assert \
+[#if (!(defined __clang__ \
+       ? (defined __cplusplus \
+          ? __cplusplus >= 201703L \
+          : __STDC_VERSION__ >= 202000L && __clang_major__ >= 16 \
+            && !defined __sun) \
+       : (defined __GNUC__ \
+          ? (defined __cplusplus \
+             ? __cplusplus >= 201103L && __GNUG__ >= 6 \
+             : __STDC_VERSION__ >= 202000L && __GNUC__ >= 13 \
+               && !defined __sun) \
+          : defined HAVE_C_STATIC_ASSERT)) \
+     && !defined assert \
      && (!defined __cplusplus \
          || (__cpp_static_assert < 201411 \
              && __GNUG__ < 6 && __clang_major__ < 6)))
  #include <assert.h>
  #undef/**/assert
+ #ifdef __sgi
+  #undef/**/__ASSERT_H__
+ #endif
  /* Solaris 11.4 <assert.h> defines static_assert as a macro with 2 arguments.
-    We need it also to be invocable with a single argument.  */
- #if defined __sun && (__STDC_VERSION__ - 0 >= 201112L) && !defined __cplusplus
+    We need it also to be invocable with a single argument.
+    Haiku 2022 <assert.h> does not define static_assert at all.  */
+ #if (__STDC_VERSION__ - 0 >= 201112L) && !defined __cplusplus
   #undef/**/static_assert
   #define static_assert _Static_assert
  #endif
diff --git a/gl/m4/base64.m4 b/gl/m4/base64.m4
index 987930ab..785d31c0 100644
--- a/gl/m4/base64.m4
+++ b/gl/m4/base64.m4
@@ -1,8 +1,10 @@
-# base64.m4 serial 4
-dnl Copyright (C) 2004, 2006, 2009-2023 Free Software Foundation, Inc.
+# base64.m4
+# serial 4
+dnl Copyright (C) 2004, 2006, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_BASE64],
 [
diff --git a/gl/m4/btowc.m4 b/gl/m4/btowc.m4
index 77218a7d..59d52be6 100644
--- a/gl/m4/btowc.m4
+++ b/gl/m4/btowc.m4
@@ -1,12 +1,15 @@
-# btowc.m4 serial 12
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# btowc.m4
+# serial 15
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_BTOWC],
 [
   AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+  AC_REQUIRE([gt_TYPE_WINT_T])
 
   dnl Check whether <wchar.h> is usable at all, first. Otherwise the test
   dnl program below may lead to an endless loop. See
@@ -40,12 +43,12 @@ int main ()
           [
 changequote(,)dnl
            case "$host_os" in
-                      # Guess no on Cygwin.
-             cygwin*) gl_cv_func_btowc_nul="guessing no" ;;
-                      # Guess yes on native Windows.
-             mingw*)  gl_cv_func_btowc_nul="guessing yes" ;;
-                      # Guess yes otherwise.
-             *)       gl_cv_func_btowc_nul="guessing yes" ;;
+                                # Guess no on Cygwin.
+             cygwin*)           gl_cv_func_btowc_nul="guessing no" ;;
+                                # Guess yes on native Windows.
+             mingw* | windows*) gl_cv_func_btowc_nul="guessing yes" ;;
+                                # Guess yes otherwise.
+             *)                 gl_cv_func_btowc_nul="guessing yes" ;;
            esac
 changequote([,])dnl
           ])
@@ -59,12 +62,12 @@ changequote([,])dnl
         dnl is present.
 changequote(,)dnl
         case "$host_os" in
-                  # Guess no on IRIX.
-          irix*)  gl_cv_func_btowc_eof="guessing no" ;;
-                  # Guess yes on native Windows.
-          mingw*) gl_cv_func_btowc_eof="guessing yes" ;;
-                  # Guess yes otherwise.
-          *)      gl_cv_func_btowc_eof="guessing yes" ;;
+                             # Guess no on IRIX.
+          irix*)             gl_cv_func_btowc_eof="guessing no" ;;
+                             # Guess yes on native Windows.
+          mingw* | windows*) gl_cv_func_btowc_eof="guessing yes" ;;
+                             # Guess yes otherwise.
+          *)                 gl_cv_func_btowc_eof="guessing yes" ;;
         esac
 changequote([,])dnl
         if test $LOCALE_FR != none; then
@@ -88,6 +91,57 @@ int main ()
         fi
       ])
 
+    dnl On mingw, in the C locale, btowc is inconsistent with mbrtowc:
+    dnl mbrtowc avoids calling MultiByteToWideChar when MB_CUR_MAX is 1 and
+    dnl ___lc_codepage_func() is 0, but btowc is lacking this special case.
+    AC_CHECK_FUNCS_ONCE([mbrtowc])
+    AC_CACHE_CHECK([whether btowc is consistent with mbrtowc in the C locale],
+      [gl_cv_func_btowc_consistent],
+      [
+        AC_RUN_IFELSE(
+          [AC_LANG_SOURCE([[
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+int main ()
+{
+#if HAVE_MBRTOWC
+  wint_t wc1 = btowc (0x80);
+  wchar_t wc2 = (wchar_t) 0xbadface;
+  char buf[1] = { 0x80 };
+  mbstate_t state;
+  memset (&state, 0, sizeof (mbstate_t));
+  if (mbrtowc (&wc2, buf, 1, &state) != 1 || wc1 != wc2)
+    return 1;
+#endif
+  return 0;
+}]])],
+          [gl_cv_func_btowc_consistent=yes],
+          [gl_cv_func_btowc_consistent=no],
+          [case "$host_os" in
+               # Guess no on mingw.
+             mingw* | windows*)
+               AC_EGREP_CPP([Problem], [
+#ifdef __MINGW32__
+ Problem
+#endif
+                 ],
+                 [gl_cv_func_btowc_consistent="guessing no"],
+                 [gl_cv_func_btowc_consistent="guessing yes"])
+               ;;
+               # Guess yes otherwise.
+             *) gl_cv_func_btowc_consistent="guessing yes" ;;
+           esac
+          ])
+      ])
+
+    if test $GNULIBHEADERS_OVERRIDE_WINT_T = 1; then
+      dnl On mingw/ucrt, we override the return type of btowc().
+      dnl While the original wint_t (= unsigned short) and the overridden wint_t
+      dnl (= unsigned int) are equivalent in function parameters, this is not
+      dnl the case for function return types.
+      REPLACE_BTOWC=1
+    fi
     case "$gl_cv_func_btowc_nul" in
       *yes) ;;
       *) REPLACE_BTOWC=1 ;;
@@ -96,10 +150,22 @@ int main ()
       *yes) ;;
       *) REPLACE_BTOWC=1 ;;
     esac
+    case "$gl_cv_func_btowc_consistent" in
+      *yes) ;;
+      *) REPLACE_BTOWC=1 ;;
+    esac
+    if test $REPLACE_BTOWC = 0; then
+      gl_MBRTOWC_C_LOCALE
+      case "$gl_cv_func_mbrtowc_C_locale_sans_EILSEQ" in
+        *yes) ;;
+        *) REPLACE_BTOWC=1 ;;
+      esac
+    fi
   fi
 ])
 
 # Prerequisites of lib/btowc.c.
 AC_DEFUN([gl_PREREQ_BTOWC], [
   :
+  AC_CHECK_FUNCS_ONCE([mbrtowc])
 ])
diff --git a/gl/m4/build-to-host.m4 b/gl/m4/build-to-host.m4
new file mode 100644
index 00000000..01bff8f3
--- /dev/null
+++ b/gl/m4/build-to-host.m4
@@ -0,0 +1,274 @@
+# build-to-host.m4
+# serial 5
+dnl Copyright (C) 2023-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl Written by Bruno Haible.
+
+dnl When the build environment ($build_os) is different from the target runtime
+dnl environment ($host_os), file names may need to be converted from the build
+dnl environment syntax to the target runtime environment syntax. This is
+dnl because the Makefiles are executed (mostly) by build environment tools and
+dnl therefore expect file names in build environment syntax, whereas the runtime
+dnl expects file names in target runtime environment syntax.
+dnl
+dnl For example, if $build_os = cygwin and $host_os = mingw32, filenames need
+dnl be converted from Cygwin syntax to native Windows syntax:
+dnl   /cygdrive/c/foo/bar -> C:\foo\bar
+dnl   /usr/local/share    -> C:\cygwin64\usr\local\share
+dnl
+dnl gl_BUILD_TO_HOST([somedir])
+dnl This macro takes as input an AC_SUBSTed variable 'somedir', which must
+dnl already have its final value assigned, and produces two additional
+dnl AC_SUBSTed variables 'somedir_c' and 'somedir_c_make', that designate the
+dnl same file name value, just in different syntax:
+dnl   - somedir_c       is the file name in target runtime environment syntax,
+dnl                     as a C string (starting and ending with a double-quote,
+dnl                     and with escaped backslashes and double-quotes in
+dnl                     between).
+dnl   - somedir_c_make  is the same thing, escaped for use in a Makefile.
+
+AC_DEFUN([gl_BUILD_TO_HOST],
+[
+  AC_REQUIRE([AC_CANONICAL_BUILD])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_BUILD_TO_HOST_INIT])
+
+  dnl Define somedir_c.
+  gl_final_[$1]="$[$1]"
+  dnl Translate it from build syntax to host syntax.
+  case "$build_os" in
+    cygwin*)
+      case "$host_os" in
+        mingw* | windows*)
+          gl_final_[$1]=`cygpath -w "$gl_final_[$1]"` ;;
+      esac
+      ;;
+  esac
+  dnl Convert it to C string syntax.
+  [$1]_c=`printf '%s\n' "$gl_final_[$1]" | sed -e "$gl_sed_double_backslashes" -e "$gl_sed_escape_doublequotes" | tr -d "$gl_tr_cr"`
+  [$1]_c='"'"$[$1]_c"'"'
+  AC_SUBST([$1_c])
+
+  dnl Define somedir_c_make.
+  [$1]_c_make=`printf '%s\n' "$[$1]_c" | sed -e "$gl_sed_escape_for_make_1" -e "$gl_sed_escape_for_make_2" | tr -d "$gl_tr_cr"`
+  dnl Use the substituted somedir variable, when possible, so that the user
+  dnl may adjust somedir a posteriori when there are no special characters.
+  if test "$[$1]_c_make" = '\"'"${gl_final_[$1]}"'\"'; then
+    [$1]_c_make='\"$([$1])\"'
+  fi
+  AC_SUBST([$1_c_make])
+])
+
+dnl Some initializations for gl_BUILD_TO_HOST.
+AC_DEFUN([gl_BUILD_TO_HOST_INIT],
+[
+  gl_sed_double_backslashes='s/\\/\\\\/g'
+  gl_sed_escape_doublequotes='s/"/\\"/g'
+changequote(,)dnl
+  gl_sed_escape_for_make_1="s,\\([ \"&'();<>\\\\\`|]\\),\\\\\\1,g"
+changequote([,])dnl
+  gl_sed_escape_for_make_2='s,\$,\\$$,g'
+  dnl Find out how to remove carriage returns from output. Solaris /usr/ucb/tr
+  dnl does not understand '\r'.
+  case `echo r | tr -d '\r'` in
+    '') gl_tr_cr='\015' ;;
+    *)  gl_tr_cr='\r' ;;
+  esac
+])
+
+
+dnl The following macros are convenience invocations of gl_BUILD_TO_HOST
+dnl for some of the variables that are defined by Autoconf.
+dnl To do so for _all_ the possible variables, use the module 'configmake'.
+
+dnl Defines bindir_c and bindir_c_make.
+AC_DEFUN_ONCE([gl_BUILD_TO_HOST_BINDIR],
+[
+  dnl Find the final value of bindir.
+  gl_saved_prefix="${prefix}"
+  gl_saved_exec_prefix="${exec_prefix}"
+  gl_saved_bindir="${bindir}"
+  dnl Unfortunately, prefix and exec_prefix get only finally determined
+  dnl at the end of configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  if test "X$exec_prefix" = "XNONE"; then
+    exec_prefix='${prefix}'
+  fi
+  eval exec_prefix="$exec_prefix"
+  eval bindir="$bindir"
+  gl_BUILD_TO_HOST([bindir])
+  bindir="${gl_saved_bindir}"
+  exec_prefix="${gl_saved_exec_prefix}"
+  prefix="${gl_saved_prefix}"
+])
+
+dnl Defines datadir_c and datadir_c_make,
+dnl where datadir = $(datarootdir)
+AC_DEFUN_ONCE([gl_BUILD_TO_HOST_DATADIR],
+[
+  dnl Find the final value of datadir.
+  gl_saved_prefix="${prefix}"
+  gl_saved_datarootdir="${datarootdir}"
+  gl_saved_datadir="${datadir}"
+  dnl Unfortunately, prefix gets only finally determined at the end of
+  dnl configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  eval datarootdir="$datarootdir"
+  eval datadir="$datadir"
+  gl_BUILD_TO_HOST([datadir])
+  datadir="${gl_saved_datadir}"
+  datarootdir="${gl_saved_datarootdir}"
+  prefix="${gl_saved_prefix}"
+])
+
+dnl Defines libdir_c and libdir_c_make.
+AC_DEFUN_ONCE([gl_BUILD_TO_HOST_LIBDIR],
+[
+  dnl Find the final value of libdir.
+  gl_saved_prefix="${prefix}"
+  gl_saved_exec_prefix="${exec_prefix}"
+  gl_saved_libdir="${libdir}"
+  dnl Unfortunately, prefix and exec_prefix get only finally determined
+  dnl at the end of configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  if test "X$exec_prefix" = "XNONE"; then
+    exec_prefix='${prefix}'
+  fi
+  eval exec_prefix="$exec_prefix"
+  eval libdir="$libdir"
+  gl_BUILD_TO_HOST([libdir])
+  libdir="${gl_saved_libdir}"
+  exec_prefix="${gl_saved_exec_prefix}"
+  prefix="${gl_saved_prefix}"
+])
+
+dnl Defines libexecdir_c and libexecdir_c_make.
+AC_DEFUN_ONCE([gl_BUILD_TO_HOST_LIBEXECDIR],
+[
+  dnl Find the final value of libexecdir.
+  gl_saved_prefix="${prefix}"
+  gl_saved_exec_prefix="${exec_prefix}"
+  gl_saved_libexecdir="${libexecdir}"
+  dnl Unfortunately, prefix and exec_prefix get only finally determined
+  dnl at the end of configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  if test "X$exec_prefix" = "XNONE"; then
+    exec_prefix='${prefix}'
+  fi
+  eval exec_prefix="$exec_prefix"
+  eval libexecdir="$libexecdir"
+  gl_BUILD_TO_HOST([libexecdir])
+  libexecdir="${gl_saved_libexecdir}"
+  exec_prefix="${gl_saved_exec_prefix}"
+  prefix="${gl_saved_prefix}"
+])
+
+dnl Defines localedir_c and localedir_c_make.
+AC_DEFUN_ONCE([gl_BUILD_TO_HOST_LOCALEDIR],
+[
+  dnl Find the final value of localedir.
+  gl_saved_prefix="${prefix}"
+  gl_saved_datarootdir="${datarootdir}"
+  gl_saved_localedir="${localedir}"
+  dnl Unfortunately, prefix gets only finally determined at the end of
+  dnl configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  eval datarootdir="$datarootdir"
+  eval localedir="$localedir"
+  gl_BUILD_TO_HOST([localedir])
+  localedir="${gl_saved_localedir}"
+  datarootdir="${gl_saved_datarootdir}"
+  prefix="${gl_saved_prefix}"
+])
+
+dnl Defines pkgdatadir_c and pkgdatadir_c_make,
+dnl where pkgdatadir = $(datadir)/$(PACKAGE)
+AC_DEFUN_ONCE([gl_BUILD_TO_HOST_PKGDATADIR],
+[
+  dnl Find the final value of pkgdatadir.
+  gl_saved_prefix="${prefix}"
+  gl_saved_datarootdir="${datarootdir}"
+  gl_saved_datadir="${datadir}"
+  gl_saved_pkgdatadir="${pkgdatadir}"
+  dnl Unfortunately, prefix gets only finally determined at the end of
+  dnl configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  eval datarootdir="$datarootdir"
+  eval datadir="$datadir"
+  eval pkgdatadir="$pkgdatadir"
+  gl_BUILD_TO_HOST([pkgdatadir])
+  pkgdatadir="${gl_saved_pkgdatadir}"
+  datadir="${gl_saved_datadir}"
+  datarootdir="${gl_saved_datarootdir}"
+  prefix="${gl_saved_prefix}"
+])
+
+dnl Defines pkglibdir_c and pkglibdir_c_make,
+dnl where pkglibdir = $(libdir)/$(PACKAGE)
+AC_DEFUN_ONCE([gl_BUILD_TO_HOST_PKGLIBDIR],
+[
+  dnl Find the final value of pkglibdir.
+  gl_saved_prefix="${prefix}"
+  gl_saved_exec_prefix="${exec_prefix}"
+  gl_saved_libdir="${libdir}"
+  gl_saved_pkglibdir="${pkglibdir}"
+  dnl Unfortunately, prefix and exec_prefix get only finally determined
+  dnl at the end of configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  if test "X$exec_prefix" = "XNONE"; then
+    exec_prefix='${prefix}'
+  fi
+  eval exec_prefix="$exec_prefix"
+  eval libdir="$libdir"
+  eval pkglibdir="$pkglibdir"
+  gl_BUILD_TO_HOST([pkglibdir])
+  pkglibdir="${gl_saved_pkglibdir}"
+  libdir="${gl_saved_libdir}"
+  exec_prefix="${gl_saved_exec_prefix}"
+  prefix="${gl_saved_prefix}"
+])
+
+dnl Defines pkglibexecdir_c and pkglibexecdir_c_make,
+dnl where pkglibexecdir = $(libexecdir)/$(PACKAGE)
+AC_DEFUN_ONCE([gl_BUILD_TO_HOST_PKGLIBEXECDIR],
+[
+  dnl Find the final value of pkglibexecdir.
+  gl_saved_prefix="${prefix}"
+  gl_saved_exec_prefix="${exec_prefix}"
+  gl_saved_libexecdir="${libexecdir}"
+  gl_saved_pkglibexecdir="${pkglibexecdir}"
+  dnl Unfortunately, prefix and exec_prefix get only finally determined
+  dnl at the end of configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  if test "X$exec_prefix" = "XNONE"; then
+    exec_prefix='${prefix}'
+  fi
+  eval exec_prefix="$exec_prefix"
+  eval libexecdir="$libexecdir"
+  eval pkglibexecdir="$pkglibexecdir"
+  gl_BUILD_TO_HOST([pkglibexecdir])
+  pkglibexecdir="${gl_saved_pkglibexecdir}"
+  libexecdir="${gl_saved_libexecdir}"
+  exec_prefix="${gl_saved_exec_prefix}"
+  prefix="${gl_saved_prefix}"
+])
diff --git a/gl/m4/builtin-expect.m4 b/gl/m4/builtin-expect.m4
index 531ed48a..76d32867 100644
--- a/gl/m4/builtin-expect.m4
+++ b/gl/m4/builtin-expect.m4
@@ -1,9 +1,12 @@
-dnl Check for __builtin_expect.
-
-dnl Copyright 2016-2023 Free Software Foundation, Inc.
+# builtin-expect.m4
+# serial 3
+dnl Copyright 2016-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl Provide a GCC-compatible __builtin_expect macro in <config.h>.
 
 dnl Written by Paul Eggert.
 
@@ -45,5 +48,4 @@ AC_DEFUN([gl___BUILTIN_EXPECT],
 #elif HAVE___BUILTIN_EXPECT == 2
 # include <builtins.h>
 #endif
-    ])
-])
+])])
diff --git a/gl/m4/byteswap.m4 b/gl/m4/byteswap.m4
index 8058d178..b53cb4d0 100644
--- a/gl/m4/byteswap.m4
+++ b/gl/m4/byteswap.m4
@@ -1,17 +1,42 @@
-# byteswap.m4 serial 5
-dnl Copyright (C) 2005, 2007, 2009-2023 Free Software Foundation, Inc.
+# byteswap.m4
+# serial 7
+dnl Copyright (C) 2005, 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Written by Oskar Liljeblad.
 
 AC_DEFUN([gl_BYTESWAP],
 [
   dnl Prerequisites of lib/byteswap.in.h.
-  AC_CHECK_HEADERS([byteswap.h], [
+  AC_CHECK_HEADERS_ONCE([byteswap.h])
+  if test $ac_cv_header_byteswap_h = yes; then
+    AC_CACHE_CHECK([for working bswap_16, bswap_32, bswap_64],
+      [gl_cv_header_working_byteswap_h],
+      [gl_cv_header_working_byteswap_h=no
+       dnl Check that floating point arguments work.
+       dnl This also checks C libraries with implementations like
+       dnl '#define bswap_16(x) (((x) >> 8 & 0xff) | (((x) & 0xff) << 8))'
+       dnl that mistakenly evaluate their arguments multiple times.
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <byteswap.h>
+            ]],
+            [[int value_16 = bswap_16 (0.0);
+              int value_32 = bswap_32 (0.0);
+              int value_64 = bswap_64 (0.0);
+              return !(value_16 + value_32 + value_64);
+            ]])
+         ],
+         [gl_cv_header_working_byteswap_h=yes],
+         [gl_cv_header_working_byteswap_h=no])
+      ])
+  fi
+  if test "$gl_cv_header_working_byteswap_h" = yes; then
     GL_GENERATE_BYTESWAP_H=false
-  ], [
+  else
     GL_GENERATE_BYTESWAP_H=true
-  ])
+  fi
 ])
diff --git a/gl/m4/c-bool.m4 b/gl/m4/c-bool.m4
index f614371b..8fa8bfc8 100644
--- a/gl/m4/c-bool.m4
+++ b/gl/m4/c-bool.m4
@@ -1,9 +1,12 @@
-# Check for bool that conforms to C2023.
-
-dnl Copyright 2022-2023 Free Software Foundation, Inc.
+# c-bool.m4
+# serial 3
+dnl Copyright 2022-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+# Check for bool that conforms to C2023.
 
 AC_DEFUN([gl_C_BOOL],
 [
@@ -27,12 +30,23 @@ AC_DEFUN([gl_C_BOOL],
   dnl The "zz" puts this toward config.h's end, to avoid potential
   dnl collisions with other definitions.
   dnl If 'bool', 'true' and 'false' do not work, arrange for them to work.
-  dnl In C, this means including <stdbool.h> if it is not already included.
+  dnl Hardcode the known configuration results for GCC and clang, so that
+  dnl a configuration made with the C compiler works also with the C++ compiler
+  dnl and vice versa.
+  dnl The seemingly redundant parentheses are necessary for MSVC 14.
+  dnl "Arrange for them to work", in C, means including <stdbool.h> if it is
+  dnl not already included.
   dnl However, if the preprocessor mistakenly treats 'true' as 0,
   dnl define it to a bool expression equal to 1; this is needed in
   dnl Sun C++ 5.11 (Oracle Solaris Studio 12.2, 2010) and older.
   AH_VERBATIM([zzbool],
-[#ifndef HAVE_C_BOOL
+[#if !(defined __cplusplus \
+      ? 1 \
+      : (defined __clang__ \
+         ? __STDC_VERSION__ >= 202000L && __clang_major__ >= 15 \
+         : (defined __GNUC__ \
+            ? __STDC_VERSION__ >= 202000L && __GNUC__ >= 13 \
+            : defined HAVE_C_BOOL)))
 # if !defined __cplusplus && !defined __bool_true_false_are_defined
 #  if HAVE_STDBOOL_H
 #   include <stdbool.h>
diff --git a/gl/m4/c32rtomb.m4 b/gl/m4/c32rtomb.m4
new file mode 100644
index 00000000..ce26a31e
--- /dev/null
+++ b/gl/m4/c32rtomb.m4
@@ -0,0 +1,187 @@
+# c32rtomb.m4
+# serial 8
+dnl Copyright (C) 2020-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_C32RTOMB],
+[
+  AC_REQUIRE([gl_UCHAR_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+
+  AC_REQUIRE([gl_CHECK_FUNC_C32RTOMB])
+  if test $gl_cv_func_c32rtomb = no; then
+    HAVE_C32RTOMB=0
+  else
+    dnl When we override mbrtoc32, redefining the meaning of the char32_t
+    dnl values, we need to override c32rtomb as well, for consistency.
+    if test $HAVE_WORKING_MBRTOC32 = 0; then
+      REPLACE_C32RTOMB=1
+    fi
+    AC_CACHE_CHECK([whether c32rtomb return value is correct],
+      [gl_cv_func_c32rtomb_retval],
+      [
+        dnl Initial guess, used when cross-compiling.
+changequote(,)dnl
+        case "$host_os" in
+          # Guess no on AIX.
+          aix*) gl_cv_func_c32rtomb_retval="guessing no" ;;
+          # Guess yes otherwise.
+          *)    gl_cv_func_c32rtomb_retval="guessing yes" ;;
+        esac
+changequote([,])dnl
+        AC_RUN_IFELSE(
+          [AC_LANG_SOURCE([[
+#include <stddef.h>
+#ifdef __HAIKU__
+ #include <stdint.h>
+#endif
+#include <uchar.h>
+int main ()
+{
+  int result = 0;
+  if (c32rtomb (NULL, 0, NULL) != 1)
+    result |= 1;
+  return result;
+}]])],
+          [gl_cv_func_c32rtomb_retval=yes],
+          [gl_cv_func_c32rtomb_retval=no],
+          [:])
+      ])
+    case "$gl_cv_func_c32rtomb_retval" in
+      *yes) ;;
+      *) AC_DEFINE([C32RTOMB_RETVAL_BUG], [1],
+           [Define if the c32rtomb function has an incorrect return value.])
+         REPLACE_C32RTOMB=1 ;;
+    esac
+    if test $HAVE_WORKING_C32RTOMB = 0; then
+      REPLACE_C32RTOMB=1
+    fi
+  fi
+])
+
+AC_DEFUN([gl_CHECK_FUNC_C32RTOMB],
+[
+  dnl Cf. gl_CHECK_FUNCS_ANDROID
+  AC_CHECK_DECL([c32rtomb], , ,
+    [[#ifdef __HAIKU__
+       #include <stdint.h>
+      #endif
+      #include <uchar.h>
+    ]])
+  if test $ac_cv_have_decl_c32rtomb = yes; then
+    dnl We can't use AC_CHECK_FUNC here, because c32rtomb() is defined as a
+    dnl static inline function on Haiku 2020.
+    AC_CACHE_CHECK([for c32rtomb], [gl_cv_func_c32rtomb],
+      [AC_LINK_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <stdlib.h>
+              #ifdef __HAIKU__
+               #include <stdint.h>
+              #endif
+              #include <uchar.h>
+            ]],
+            [[char buf[8];
+              return c32rtomb (buf, 0, NULL) == 0;
+            ]])
+         ],
+         [gl_cv_func_c32rtomb=yes],
+         [gl_cv_func_c32rtomb=no])
+      ])
+  else
+    gl_cv_func_c32rtomb=no
+  fi
+])
+
+dnl Test whether c32rtomb works not worse than wcrtomb.
+dnl Result is HAVE_WORKING_C32RTOMB.
+
+AC_DEFUN([gl_C32RTOMB_SANITYCHECK],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([gl_TYPE_CHAR32_T])
+  AC_REQUIRE([gl_CHECK_FUNC_C32RTOMB])
+  AC_REQUIRE([gt_LOCALE_ZH_CN])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  if test $GNULIBHEADERS_OVERRIDE_CHAR32_T = 1 || test $gl_cv_func_c32rtomb = no; then
+    HAVE_WORKING_C32RTOMB=0
+  else
+    AC_CACHE_CHECK([whether c32rtomb works as well as wcrtomb],
+      [gl_cv_func_c32rtomb_sanitycheck],
+      [
+        dnl Initial guess, used when cross-compiling or when no suitable locale
+        dnl is present.
+changequote(,)dnl
+        case "$host_os" in
+          # Guess no on Solaris derivatives.
+          solaris*)
+            if test -f /etc/release && grep 'Oracle Solaris' /etc/release >/dev/null; then
+              gl_cv_func_c32rtomb_sanitycheck="guessing yes"
+            else
+              gl_cv_func_c32rtomb_sanitycheck="guessing no"
+            fi
+            ;;
+          # Guess yes otherwise.
+          *)
+            gl_cv_func_c32rtomb_sanitycheck="guessing yes"
+            ;;
+        esac
+changequote([,])dnl
+        if test $LOCALE_ZH_CN != none; then
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#ifdef __HAIKU__
+ #include <stdint.h>
+#endif
+#include <uchar.h>
+int main ()
+{
+  int result = 0;
+  /* This fails on Solaris 11 OmniOS:
+     c32rtomb returns (size_t)-1.
+     wcrtomb returns 4 (correct).  */
+  if (strcmp ("$LOCALE_ZH_CN", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_ZH_CN") != NULL)
+    {
+      mbstate_t state;
+      wchar_t wc = (wchar_t) 0xBADFACE;
+      char buf[16];
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, "\201\060\211\070", 4, &state) == 4
+          && wcrtomb (buf, wc, NULL) == 4
+          && memcmp (buf, "\201\060\211\070", 4) == 0)
+        {
+          char32_t c32 = (wchar_t) 0xBADFACE;
+          memset (&state, '\0', sizeof (mbstate_t));
+          if (mbrtoc32 (&c32, "\201\060\211\070", 4, &state) == 4
+              && c32rtomb (buf, c32, NULL) != 4)
+            result |= 1;
+        }
+    }
+  return result;
+}]])],
+            [gl_cv_func_c32rtomb_sanitycheck=yes],
+            [gl_cv_func_c32rtomb_sanitycheck=no],
+            [:])
+        fi
+      ])
+    case "$gl_cv_func_c32rtomb_sanitycheck" in
+      *yes)
+        HAVE_WORKING_C32RTOMB=1
+        AC_DEFINE([HAVE_WORKING_C32RTOMB], [1],
+          [Define if the c32rtomb function basically works.])
+        ;;
+      *) HAVE_WORKING_C32RTOMB=0 ;;
+    esac
+  fi
+  AC_SUBST([HAVE_WORKING_C32RTOMB])
+])
diff --git a/gl/m4/calloc.m4 b/gl/m4/calloc.m4
index 23c0dd9f..ac7d08d4 100644
--- a/gl/m4/calloc.m4
+++ b/gl/m4/calloc.m4
@@ -1,9 +1,10 @@
-# calloc.m4 serial 29
-
-# Copyright (C) 2004-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# calloc.m4
+# serial 36
+dnl Copyright (C) 2004-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # Written by Jim Meyering.
 
@@ -12,42 +13,35 @@
 # If so, define HAVE_CALLOC.  Otherwise, define calloc to rpl_calloc
 # and arrange to use a calloc wrapper function that does work in that case.
 
-# _AC_FUNC_CALLOC_IF([IF-WORKS], [IF-NOT])
-# -------------------------------------
+# gl_FUNC_CALLOC_IF([IF-WORKS], [IF-NOT])
+# ---------------------------------------
 # If calloc is compatible with GNU calloc, run IF-WORKS, otherwise, IF-NOT.
-AC_DEFUN([_AC_FUNC_CALLOC_IF],
+AC_DEFUN([gl_FUNC_CALLOC_IF],
 [
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether calloc (0, n) and calloc (n, 0) return nonnull],
-    [ac_cv_func_calloc_0_nonnull],
-    [if test $cross_compiling != yes; then
-       ac_cv_func_calloc_0_nonnull=yes
-       AC_RUN_IFELSE(
-         [AC_LANG_PROGRAM(
-            [AC_INCLUDES_DEFAULT],
-            [[int result = 0;
-              char * volatile p = calloc (0, 0);
-              if (!p)
-                result |= 1;
-              free (p);
-              return result;
-            ]])],
-         [],
-         [ac_cv_func_calloc_0_nonnull=no])
-     else
-       case "$host_os" in
-                        # Guess yes on glibc systems.
-         *-gnu* | gnu*) ac_cv_func_calloc_0_nonnull="guessing yes" ;;
-                        # Guess yes on musl systems.
-         *-musl*)       ac_cv_func_calloc_0_nonnull="guessing yes" ;;
-                        # Guess yes on native Windows.
-         mingw*)        ac_cv_func_calloc_0_nonnull="guessing yes" ;;
-                        # If we don't know, obey --enable-cross-guesses.
-         *)             ac_cv_func_calloc_0_nonnull="$gl_cross_guess_normal" ;;
-       esac
-     fi
-    ])
-  AS_CASE([$ac_cv_func_calloc_0_nonnull], [*yes], [$1], [$2])
+    [gl_cv_func_calloc_0_nonnull],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stdlib.h>
+            /* Use pcalloc to test; "volatile" prevents the compiler
+               from optimizing the calloc call away.  */
+            void *(*volatile pcalloc) (size_t, size_t) = calloc;]],
+          [[void *p = pcalloc (0, 0);
+            int result = !p;
+            free (p);
+            return result;]])],
+       [gl_cv_func_calloc_0_nonnull=yes],
+       [gl_cv_func_calloc_0_nonnull=no],
+       [AS_CASE([$host_os],
+          [# Guess yes on platforms where we know the result.
+           *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
+           | gnu* | *-musl* | midipix* | midnightbsd* \
+           | hpux* | solaris* | cygwin* | mingw* | windows* | msys*],
+            [gl_cv_func_calloc_0_nonnull="guessing yes"],
+          [# If we don't know, obey --enable-cross-guesses.
+           gl_cv_func_calloc_0_nonnull="$gl_cross_guess_normal"])])])
+  AS_CASE([$gl_cv_func_calloc_0_nonnull], [*yes], [$1], [$2])
 ])
 
 
@@ -58,9 +52,14 @@ AC_DEFUN([gl_FUNC_CALLOC_GNU],
 [
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_CALLOC_POSIX])
+
+  dnl Through the dependency on module extensions-aix, _LINUX_SOURCE_COMPAT
+  dnl gets defined already before this macro gets invoked.  This helps
+  dnl if !(__VEC__ || __AIXVEC), and doesn't hurt otherwise.
+
   REPLACE_CALLOC_FOR_CALLOC_GNU="$REPLACE_CALLOC_FOR_CALLOC_POSIX"
   if test $REPLACE_CALLOC_FOR_CALLOC_GNU = 0; then
-    _AC_FUNC_CALLOC_IF([], [REPLACE_CALLOC_FOR_CALLOC_GNU=1])
+    gl_FUNC_CALLOC_IF([], [REPLACE_CALLOC_FOR_CALLOC_GNU=1])
   fi
 ])# gl_FUNC_CALLOC_GNU
 
@@ -73,9 +72,7 @@ AC_DEFUN([gl_FUNC_CALLOC_POSIX],
 [
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
-  if test $REPLACE_MALLOC_FOR_MALLOC_POSIX = 1; then
-    REPLACE_CALLOC_FOR_CALLOC_POSIX=1
-  fi
+  REPLACE_CALLOC_FOR_CALLOC_POSIX=$REPLACE_MALLOC_FOR_MALLOC_POSIX
   dnl Although in theory we should also test for size_t overflow,
   dnl in practice testing for ptrdiff_t overflow suffices
   dnl since PTRDIFF_MAX <= SIZE_MAX on all known Gnulib porting targets.
diff --git a/gl/m4/close.m4 b/gl/m4/close.m4
index 9f95c670..314e321e 100644
--- a/gl/m4/close.m4
+++ b/gl/m4/close.m4
@@ -1,10 +1,12 @@
-# close.m4 serial 9
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# close.m4
+# serial 10
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-AC_DEFUN([gl_FUNC_CLOSE],
+AC_DEFUN_ONCE([gl_FUNC_CLOSE],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   m4_ifdef([gl_MSVC_INVAL], [
diff --git a/gl/m4/codeset.m4 b/gl/m4/codeset.m4
index 5804f472..6bed9dee 100644
--- a/gl/m4/codeset.m4
+++ b/gl/m4/codeset.m4
@@ -1,9 +1,11 @@
-# codeset.m4 serial 5 (gettext-0.18.2)
-dnl Copyright (C) 2000-2002, 2006, 2008-2014, 2016, 2019-2023 Free Software
+# codeset.m4
+# serial 5 (gettext-0.18.2)
+dnl Copyright (C) 2000-2002, 2006, 2008-2014, 2016, 2019-2025 Free Software
 dnl Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 
diff --git a/gl/m4/double-slash-root.m4 b/gl/m4/double-slash-root.m4
index 1776e5eb..5c40b73c 100644
--- a/gl/m4/double-slash-root.m4
+++ b/gl/m4/double-slash-root.m4
@@ -1,8 +1,10 @@
-# double-slash-root.m4 serial 4   -*- Autoconf -*-
-dnl Copyright (C) 2006, 2008-2023 Free Software Foundation, Inc.
+# double-slash-root.m4
+# serial 4   -*- Autoconf -*-
+dnl Copyright (C) 2006, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_DOUBLE_SLASH_ROOT],
 [
diff --git a/gl/m4/dup2.m4 b/gl/m4/dup2.m4
index e1cc73e1..5da3a0b9 100644
--- a/gl/m4/dup2.m4
+++ b/gl/m4/dup2.m4
@@ -1,8 +1,10 @@
-#serial 27
-dnl Copyright (C) 2002, 2005, 2007, 2009-2023 Free Software Foundation, Inc.
+# dup2.m4
+# serial 28
+dnl Copyright (C) 2002, 2005, 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_DUP2],
 [
@@ -67,7 +69,7 @@ AC_DEFUN([gl_FUNC_DUP2],
       ],
       [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
       [case "$host_os" in
-         mingw*) # on this platform, dup2 always returns 0 for success
+         mingw* | windows*) # on this platform, dup2 always returns 0 for success
            gl_cv_func_dup2_works="guessing no" ;;
          cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
            gl_cv_func_dup2_works="guessing no" ;;
diff --git a/gl/m4/eealloc.m4 b/gl/m4/eealloc.m4
deleted file mode 100644
index cb3e08fe..00000000
--- a/gl/m4/eealloc.m4
+++ /dev/null
@@ -1,31 +0,0 @@
-# eealloc.m4 serial 3
-dnl Copyright (C) 2003, 2009-2023 Free Software Foundation, Inc.
-dnl This file is free software; the Free Software Foundation
-dnl gives unlimited permission to copy and/or distribute it,
-dnl with or without modifications, as long as this notice is preserved.
-
-AC_DEFUN([gl_EEALLOC],
-[
-  AC_REQUIRE([gl_EEMALLOC])
-  AC_REQUIRE([gl_EEREALLOC])
-])
-
-AC_DEFUN([gl_EEMALLOC],
-[
-  _AC_FUNC_MALLOC_IF(
-    [gl_cv_func_malloc_0_nonnull=1],
-    [gl_cv_func_malloc_0_nonnull=0])
-  AC_DEFINE_UNQUOTED([MALLOC_0_IS_NONNULL], [$gl_cv_func_malloc_0_nonnull],
-    [If malloc(0) is != NULL, define this to 1.  Otherwise define this
-     to 0.])
-])
-
-AC_DEFUN([gl_EEREALLOC],
-[
-  _AC_FUNC_REALLOC_IF(
-    [gl_cv_func_realloc_0_nonnull=1],
-    [gl_cv_func_realloc_0_nonnull=0])
-  AC_DEFINE_UNQUOTED([REALLOC_0_IS_NONNULL], [$gl_cv_func_realloc_0_nonnull],
-    [If realloc(NULL,0) is != NULL, define this to 1.  Otherwise define this
-     to 0.])
-])
diff --git a/gl/m4/environ.m4 b/gl/m4/environ.m4
index 741dfc56..e0690e54 100644
--- a/gl/m4/environ.m4
+++ b/gl/m4/environ.m4
@@ -1,8 +1,10 @@
-# environ.m4 serial 8
-dnl Copyright (C) 2001-2004, 2006-2023 Free Software Foundation, Inc.
+# environ.m4
+# serial 8
+dnl Copyright (C) 2001-2004, 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_ENVIRON],
 [
diff --git a/gl/m4/errno_h.m4 b/gl/m4/errno_h.m4
index 4c70d225..420d5bb3 100644
--- a/gl/m4/errno_h.m4
+++ b/gl/m4/errno_h.m4
@@ -1,14 +1,21 @@
-# errno_h.m4 serial 14
-dnl Copyright (C) 2004, 2006, 2008-2023 Free Software Foundation, Inc.
+# errno_h.m4
+# serial 18
+dnl Copyright (C) 2004, 2006, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_PREREQ([2.61])
 
 AC_DEFUN_ONCE([gl_HEADER_ERRNO_H],
 [
   AC_REQUIRE([AC_PROG_CC])
+
+  dnl Through the dependency on module extensions-aix, _LINUX_SOURCE_COMPAT
+  dnl gets defined already before this macro gets invoked.  This persuades
+  dnl AIX 7.3 errno.h to assign ENOTEMPTY a value different than EEXIST.
+
   AC_CACHE_CHECK([for complete errno.h], [gl_cv_header_errno_h_complete], [
     AC_EGREP_CPP([booboo],[
 #include <errno.h>
@@ -63,6 +70,9 @@ booboo
 #if !defined EILSEQ
 booboo
 #endif
+#if !defined ESOCKTNOSUPPORT
+booboo
+#endif
       ],
       [gl_cv_header_errno_h_complete=no],
       [gl_cv_header_errno_h_complete=yes])
diff --git a/gl/m4/error.m4 b/gl/m4/error.m4
index 8cc75dff..1572250a 100644
--- a/gl/m4/error.m4
+++ b/gl/m4/error.m4
@@ -1,22 +1,14 @@
-#serial 15
-
-# Copyright (C) 1996-1998, 2001-2004, 2009-2023 Free Software Foundation, Inc.
-#
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# error.m4
+# serial 16
+dnl Copyright (C) 1996-1998, 2001-2004, 2009-2025 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_ERROR],
 [
-  dnl We don't use AC_FUNC_ERROR_AT_LINE any more, because it is no longer
-  dnl maintained in Autoconf and because it invokes AC_LIBOBJ.
-  AC_CACHE_CHECK([for error_at_line], [ac_cv_lib_error_at_line],
-    [AC_LINK_IFELSE(
-       [AC_LANG_PROGRAM(
-          [[#include <error.h>]],
-          [[error_at_line (0, 0, "", 0, "an error occurred");]])],
-       [ac_cv_lib_error_at_line=yes],
-       [ac_cv_lib_error_at_line=no])])
 ])
 
 # Prerequisites of lib/error.c.
diff --git a/gl/m4/error_h.m4 b/gl/m4/error_h.m4
new file mode 100644
index 00000000..4ef5cbff
--- /dev/null
+++ b/gl/m4/error_h.m4
@@ -0,0 +1,129 @@
+# error_h.m4
+# serial 5
+dnl Copyright (C) 1996-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl From Bruno Haible.
+dnl Provide a working <error.h>.
+
+AC_DEFUN_ONCE([gl_ERROR_H],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  gl_CHECK_NEXT_HEADERS([error.h])
+  if test $ac_cv_header_error_h = yes; then
+    HAVE_ERROR_H=1
+  else
+    HAVE_ERROR_H=0
+  fi
+  AC_SUBST([HAVE_ERROR_H])
+
+  REPLACE_ERROR=0
+
+  gl_CHECK_FUNCS_ANDROID([error], [[#include <error.h>]])
+  if test $ac_cv_func_error = yes; then
+    HAVE_ERROR=1
+  else
+    HAVE_ERROR=0
+    case "$gl_cv_onwards_func_error" in
+      future*) REPLACE_ERROR=1 ;;
+    esac
+  fi
+
+  dnl We don't use AC_FUNC_ERROR_AT_LINE any more, because it is no longer
+  dnl maintained in Autoconf and because it invokes AC_LIBOBJ.
+  dnl We need to notice a missing declaration, like gl_CHECK_FUNCS_ANDROID does.
+  AC_CHECK_DECL([error_at_line], , , [[#include <error.h>]])
+  if test $ac_cv_have_decl_error_at_line = yes; then
+    AC_CACHE_CHECK([for error_at_line], [ac_cv_lib_error_at_line],
+      [AC_LINK_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <error.h>]],
+            [[error_at_line (0, 0, "", 0, "an error occurred");]])],
+         [ac_cv_lib_error_at_line=yes],
+         [ac_cv_lib_error_at_line=no])])
+  else
+    ac_cv_lib_error_at_line=no
+  fi
+  if test $ac_cv_lib_error_at_line = yes; then
+    HAVE_ERROR_AT_LINE=1
+  else
+    HAVE_ERROR_AT_LINE=0
+  fi
+  REPLACE_ERROR_AT_LINE=0
+
+  if test $ac_cv_func_error = yes && test $ac_cv_lib_error_at_line = yes; then
+    dnl On Android 11, when error_print_progname is set, the output of the
+    dnl error() function contains an extra space.
+    AC_CACHE_CHECK([for working error function],
+      [gl_cv_func_working_error],
+      [if test $cross_compiling != yes; then
+         AC_LINK_IFELSE(
+           [AC_LANG_PROGRAM([[
+              #include <error.h>
+              static void print_no_progname (void) {}
+            ]], [[
+              error_print_progname = print_no_progname;
+              error (0, 0, "foo");
+            ]])
+           ],
+           [rm -f conftest.out
+            if test -s conftest$ac_exeext \
+               && ./conftest$ac_exeext 2> conftest.out; then
+              if grep ' ' conftest.out >/dev/null; then
+                gl_cv_func_working_error=no
+              else
+                gl_cv_func_working_error=yes
+              fi
+            else
+              gl_cv_func_working_error=no
+            fi
+            rm -f conftest.out
+           ],
+           [gl_cv_func_working_error=no])
+       else
+         AC_COMPILE_IFELSE(
+           [AC_LANG_PROGRAM([[
+              #include <error.h>
+            ]], [[
+              error (0, 0, "foo");
+            ]])
+           ],
+           [case "$host_os" in
+                               # Guess yes on glibc systems.
+              *-gnu* | gnu*)   gl_cv_func_working_error="guessing yes" ;;
+                               # Guess no on Android.
+              linux*-android*) gl_cv_func_working_error="guessing no" ;;
+                               # If we don't know, obey --enable-cross-guesses.
+              *)               gl_cv_func_working_error="$gl_cross_guess_normal" ;;
+            esac
+           ],
+           [gl_cv_func_working_error=no])
+       fi
+      ])
+    case "$gl_cv_func_working_error" in
+      *no)
+        REPLACE_ERROR=1
+        REPLACE_ERROR_AT_LINE=1
+        ;;
+    esac
+  fi
+
+  m4_ifdef([gl_HAVE_MODULE_VERROR],
+    [COMPILE_ERROR_C=1],
+    [if test $HAVE_ERROR = 0 || test $REPLACE_ERROR = 1 \
+        || test $HAVE_ERROR_AT_LINE = 0 \
+        || test $REPLACE_ERROR_AT_LINE = 1; then
+       COMPILE_ERROR_C=1
+     else
+       COMPILE_ERROR_C=0
+     fi])
+
+  AC_SUBST([HAVE_ERROR])
+  AC_SUBST([HAVE_ERROR_AT_LINE])
+  AC_SUBST([REPLACE_ERROR])
+  AC_SUBST([REPLACE_ERROR_AT_LINE])
+])
diff --git a/gl/m4/exponentd.m4 b/gl/m4/exponentd.m4
index 2ef46437..08e93397 100644
--- a/gl/m4/exponentd.m4
+++ b/gl/m4/exponentd.m4
@@ -1,9 +1,11 @@
-# exponentd.m4 serial 3
-dnl Copyright (C) 2007-2008, 2010-2023 Free Software Foundation, Inc.
+# exponentd.m4
+# serial 5
+dnl Copyright (C) 2007-2008, 2010-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
-AC_DEFUN([gl_DOUBLE_EXPONENT_LOCATION],
+dnl This file is offered as-is, without any warranty.
+AC_DEFUN_ONCE([gl_DOUBLE_EXPONENT_LOCATION],
 [
   AC_CACHE_CHECK([where to find the exponent in a 'double'],
     [gl_cv_cc_double_expbit0],
@@ -83,7 +85,7 @@ int main ()
           dnl The newer VFP instructions assume little-endian order
           dnl consistently.
           AC_EGREP_CPP([mixed_endianness], [
-#if defined arm || defined __arm || defined __arm__
+#if defined __arm__
   mixed_endianness
 #endif
             ],
diff --git a/gl/m4/extensions-aix.m4 b/gl/m4/extensions-aix.m4
new file mode 100644
index 00000000..08b703b4
--- /dev/null
+++ b/gl/m4/extensions-aix.m4
@@ -0,0 +1,26 @@
+# extensions-aix.m4
+# serial 1
+dnl Copyright (C) 2024-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+# On AIX, most extensions are already enabled through the _ALL_SOURCE macro,
+# defined by gl_USE_SYSTEM_EXTENSIONS.  gl_USE_AIX_EXTENSIONS additionally
+# activates more GNU and Linux-like behaviours, affecting
+#   - the time_t type,
+#   - errno values in <errno.h>: ENOTEMPTY
+#   - functions in <stdlib.h>: malloc calloc realloc valloc
+#     <https://www.ibm.com/docs/en/aix/7.3?topic=m-malloc-free-realloc-calloc-mallopt-mallinfo-mallinfo-heap-alloca-valloc-posix-memalign-subroutine>
+#   - functions in <string.h>: strerror_r (returns 'char *', like glibc)
+#   - functions in <dirent.h>: scandir, alphasort, readdir_r
+#   - functions in <netdb.h>: gethostbyname_r gethostbyaddr_r
+#   - declarations in <unistd.h>: sbrk
+# and a couple of secondary <sys/*> header files.
+
+AC_DEFUN_ONCE([gl_USE_AIX_EXTENSIONS],
+[
+  AC_DEFINE([_LINUX_SOURCE_COMPAT], [1],
+    [Define so that AIX headers are more compatible with GNU/Linux.])
+])
diff --git a/gl/m4/extensions.m4 b/gl/m4/extensions.m4
index 5336b8da..76516bce 100644
--- a/gl/m4/extensions.m4
+++ b/gl/m4/extensions.m4
@@ -1,10 +1,12 @@
-# serial 23  -*- Autoconf -*-
-# Enable extensions on systems that normally disable them.
+# extensions.m4
+# serial 25  -*- Autoconf -*-
+dnl Copyright (C) 2003, 2006-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# Copyright (C) 2003, 2006-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# Enable extensions on systems that normally disable them.
 
 dnl Define to empty for the benefit of Autoconf 2.69 and earlier, so that
 dnl AC_USE_SYSTEM_EXTENSIONS (below) can be used unchanged from Autoconf 2.70+.
@@ -229,4 +231,15 @@ AC_DEFUN_ONCE([gl_USE_SYSTEM_EXTENSIONS],
         [Define to enable the declarations of ISO C 11 types and functions.])
       ;;
   esac
+
+  dnl On OpenSolaris derivatives, the include files contains a couple of
+  dnl declarations that are only activated with an explicit
+  dnl -D__STDC_WANT_LIB_EXT1__.
+  AH_VERBATIM([USE_ISO_C_23_ANNEX_K_EXTENSIONS],
+[/* Define to enable the declarations of ISO C 23 Annex K types and functions.  */
+#if !(defined __STDC_WANT_LIB_EXT1__ && __STDC_WANT_LIB_EXT1__)
+#undef/**/__STDC_WANT_LIB_EXT1__
+#define __STDC_WANT_LIB_EXT1__ 1
+#endif
+])
 ])
diff --git a/gl/m4/extern-inline.m4 b/gl/m4/extern-inline.m4
index c001b1cf..d4fe6d82 100644
--- a/gl/m4/extern-inline.m4
+++ b/gl/m4/extern-inline.m4
@@ -1,9 +1,12 @@
-dnl 'extern inline' a la ISO C99.
-
-dnl Copyright 2012-2023 Free Software Foundation, Inc.
+# extern-inline.m4
+# serial 1
+dnl Copyright 2012-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl 'extern inline' a la ISO C99.
 
 AC_DEFUN([gl_EXTERN_INLINE],
 [
@@ -79,7 +82,8 @@ AC_DEFUN([gl_EXTERN_INLINE],
 # define _GL_EXTERN_INLINE_STDHEADER_BUG
 #endif
 #if ((__GNUC__ \
-      ? defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__ \
+      ? (defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__ \
+         && !defined __PCC__) \
       : (199901L <= __STDC_VERSION__ \
          && !defined __HP_cc \
          && !defined __PGI \
@@ -89,6 +93,7 @@ AC_DEFUN([gl_EXTERN_INLINE],
 # define _GL_EXTERN_INLINE extern inline
 # define _GL_EXTERN_INLINE_IN_USE
 #elif (2 < __GNUC__ + (7 <= __GNUC_MINOR__) && !defined __STRICT_ANSI__ \
+       && !defined __PCC__ \
        && !defined _GL_EXTERN_INLINE_STDHEADER_BUG)
 # if defined __GNUC_GNU_INLINE__ && __GNUC_GNU_INLINE__
    /* __gnu_inline__ suppresses a GCC 4.2 diagnostic.  */
diff --git a/gl/m4/fclose.m4 b/gl/m4/fclose.m4
new file mode 100644
index 00000000..cfb92e28
--- /dev/null
+++ b/gl/m4/fclose.m4
@@ -0,0 +1,100 @@
+# fclose.m4
+# serial 12
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_FUNC_FCLOSE],
+[
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  gl_FUNC_FFLUSH_STDIN
+  case "$gl_cv_func_fflush_stdin" in
+    *yes) ;;
+    *) REPLACE_FCLOSE=1 ;;
+  esac
+
+  AC_REQUIRE([gl_FUNC_CLOSE])
+  if test $REPLACE_CLOSE = 1; then
+    REPLACE_FCLOSE=1
+  fi
+
+  case "$host_os" in
+    openedition) REPLACE_FCLOSE=1 ;;
+  esac
+
+  if test $REPLACE_FCLOSE = 0; then
+    gl_FUNC_FCLOSE_STDIN
+    case "$gl_cv_func_fclose_stdin" in
+      *yes) ;;
+      *) REPLACE_FCLOSE=1 ;;
+    esac
+  fi
+])
+
+dnl Determine whether fclose works on input streams.
+dnl Sets gl_cv_func_fclose_stdin.
+
+AC_DEFUN([gl_FUNC_FCLOSE_STDIN],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_HEADERS_ONCE([unistd.h])
+  AC_CACHE_CHECK([whether fclose works on input streams],
+    [gl_cv_func_fclose_stdin],
+    [echo hello world > conftest.txt
+     AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <fcntl.h>
+            #include <stdio.h>
+            #if HAVE_UNISTD_H
+            # include <unistd.h>
+            #else /* on Windows with MSVC */
+            # include <io.h>
+            #endif
+           ]GL_MDA_DEFINES],
+          [[int fd;
+            int fd2;
+            FILE *fp;
+            fd = open ("conftest.txt", O_RDONLY);
+            if (fd < 0)
+              return 1;
+            if (lseek (fd, 1, SEEK_SET) != 1)
+              return 2;
+            fd2 = dup (fd);
+            if (fd2 < 0)
+              return 3;
+            fp = fdopen (fd2, "r");
+            if (fp == NULL)
+              return 4;
+            if (fgetc (fp) != 'e')
+              { fclose (fp); return 5; }
+            /* This fclose() call should reposition the underlying file
+               descriptor.  */
+            if (fclose (fp) != 0)
+              return 6;
+            if (lseek (fd2, 0, SEEK_CUR) != -1) /* should fail with EBADF */
+              return 7;
+            /* Verify the file position.  */
+            if (lseek (fd, 0, SEEK_CUR) != 2)
+              return 8;
+            return 0;
+          ]])],
+       [gl_cv_func_fclose_stdin=yes],
+       [gl_cv_func_fclose_stdin=no],
+       [case "$host_os" in
+                              # Guess no on glibc systems.
+          *-gnu* | gnu*)      gl_cv_func_fclose_stdin="guessing no" ;;
+                              # Guess yes on musl systems.
+          *-musl* | midipix*) gl_cv_func_fclose_stdin="guessing yes" ;;
+                              # Guess no on native Windows.
+          mingw* | windows*)  gl_cv_func_fclose_stdin="guessing no" ;;
+                              # If we don't know, obey --enable-cross-guesses.
+          *)                  gl_cv_func_fclose_stdin="$gl_cross_guess_normal" ;;
+        esac
+       ])
+     rm conftest.txt
+    ])
+])
diff --git a/gl/m4/fcntl-o.m4 b/gl/m4/fcntl-o.m4
index 59d558bd..8020c481 100644
--- a/gl/m4/fcntl-o.m4
+++ b/gl/m4/fcntl-o.m4
@@ -1,14 +1,17 @@
-# fcntl-o.m4 serial 7
-dnl Copyright (C) 2006, 2009-2023 Free Software Foundation, Inc.
+# fcntl-o.m4
+# serial 12
+dnl Copyright (C) 2006, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Written by Paul Eggert.
 
 AC_PREREQ([2.60])
 
-# Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
+# Test whether the flags O_DIRECTORY, O_NOATIME and O_NOFOLLOW actually work.
+# Define HAVE_WORKING_O_DIRECTORY to 1 if O_DIRECTORY works, or to 0 otherwise.
 # Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
 # Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
 AC_DEFUN([gl_FCNTL_O_FLAGS],
@@ -29,16 +32,23 @@ AC_DEFUN([gl_FCNTL_O_FLAGS],
            #else /* on Windows with MSVC */
            # include <io.h>
            # include <stdlib.h>
-           # defined sleep(n) _sleep ((n) * 1000)
+           # define sleep(n) _sleep ((n) * 1000)
            #endif
+           #include <errno.h>
            #include <fcntl.h>
            ]GL_MDA_DEFINES[
+           #ifndef O_DIRECTORY
+            #define O_DIRECTORY 0
+           #endif
            #ifndef O_NOATIME
             #define O_NOATIME 0
            #endif
            #ifndef O_NOFOLLOW
             #define O_NOFOLLOW 0
            #endif
+           #ifndef O_SEARCH
+            #define O_SEARCH O_RDONLY
+           #endif
            static int const constants[] =
             {
               O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
@@ -51,31 +61,38 @@ AC_DEFUN([gl_FCNTL_O_FLAGS],
             {
               static char const sym[] = "conftest.sym";
               if (symlink ("/dev/null", sym) != 0)
-                result |= 2;
+                result |= 1;
               else
                 {
                   int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0);
                   if (fd >= 0)
                     {
                       close (fd);
-                      result |= 4;
+                      result |= 3;
                     }
                 }
               if (unlink (sym) != 0 || symlink (".", sym) != 0)
-                result |= 2;
+                result |= 1;
               else
                 {
                   int fd = open (sym, O_RDONLY | O_NOFOLLOW);
                   if (fd >= 0)
                     {
                       close (fd);
-                      result |= 4;
+                      result |= 3;
                     }
                 }
               unlink (sym);
             }
             #endif
             {
+              int fd = open ("confdefs.h", O_SEARCH | O_DIRECTORY);
+              if (!(fd < 0 && errno == ENOTDIR))
+                result |= 4;
+              if (0 <= fd)
+                close (fd);
+            }
+            {
               static char const file[] = "confdefs.h";
               int fd = open (file, O_RDONLY | O_NOATIME);
               if (fd < 0)
@@ -110,31 +127,46 @@ AC_DEFUN([gl_FCNTL_O_FLAGS],
             }
             return result;]])],
        [gl_cv_header_working_fcntl_h=yes],
-       [case $? in #(
-        4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
-        64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
-        68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
-         *) gl_cv_header_working_fcntl_h='no';;
-        esac],
-       [case "$host_os" in
-                  # Guess 'no' on native Windows.
-          mingw*) gl_cv_header_working_fcntl_h='no' ;;
-          *)      gl_cv_header_working_fcntl_h=cross-compiling ;;
-        esac
-       ])
-    ])
+       [AS_CASE([$?],
+          dnl We cannot catch exit code 1 or 2 here, because
+          dnl - exit code 1 can occur through a compilation error on mingw (e.g.
+          dnl   when O_NOCTTY, O_NONBLOCK, O_SYNC are not defined) or when
+          dnl   result = 1, whereas
+          dnl - exit code 2 can occur through a compilation error on MSVC (e.g.
+          dnl   again when O_NOCTTY, O_NONBLOCK, O_SYNC are not defined) or when
+          dnl   result = 2.
+          [ 3], [gl_cv_header_working_fcntl_h="no (bad O_NOFOLLOW)"],
+          [ 4], [gl_cv_header_working_fcntl_h="no (bad O_DIRECTORY)"],
+          [ 7], [gl_cv_header_working_fcntl_h="no (bad O_NOFOLLOW, O_DIRECTORY)"],
+          [64], [gl_cv_header_working_fcntl_h="no (bad O_NOATIME)"],
+          [67], [gl_cv_header_working_fcntl_h="no (bad O_NOFOLLOW, O_NOATIME)"],
+          [68], [gl_cv_header_working_fcntl_h="no (bad O_DIRECTORY, O_NOATIME)"],
+          [71], [gl_cv_header_working_fcntl_h="no (bad O_NOFOLLOW, O_DIRECTORY, O_NOATIME)"],
+          [gl_cv_header_working_fcntl_h="no"])],
+       [AS_CASE([$host_os,$gl_cross_guess_normal],
+          # The O_DIRECTORY test is known to fail on Mac OS X 10.4.11 (2007)
+          # (see <https://bugs.gnu.org/78509#95>)
+          # and to succeed on Mac OS X 10.5.8 [darwin9.8.0] (2009).
+          # Guess it fails on Mac OS X 10.4.x and earlier.
+          [darwin[[0-8]].*yes],
+             [gl_cv_header_working_fcntl_h="guessing no (bad O_DIRECTORY)"],
+          # Known to be "no" on native MS-Windows.
+          [mingw* | windows*],
+             [gl_cv_header_working_fcntl_h=no],
+          [gl_cv_header_working_fcntl_h=$gl_cross_guess_normal])])])
+
+  AS_CASE([$gl_cv_header_working_fcntl_h],
+    [*O_DIRECTORY* | *no], [gl_val=0], [gl_val=1])
+  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_DIRECTORY], [$gl_val],
+    [Define to 1 if O_DIRECTORY works, 0 otherwise.])
 
-  case $gl_cv_header_working_fcntl_h in #(
-  *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
-  *) ac_val=1;;
-  esac
-  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
-    [Define to 1 if O_NOATIME works.])
+  AS_CASE([$gl_cv_header_working_fcntl_h],
+    [*O_NOATIME* | *no], [gl_val=0], [gl_val=1])
+  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$gl_val],
+    [Define to 1 if O_NOATIME works, 0 otherwise.])
 
-  case $gl_cv_header_working_fcntl_h in #(
-  *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
-  *) ac_val=1;;
-  esac
-  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
-    [Define to 1 if O_NOFOLLOW works.])
+  AS_CASE([$gl_cv_header_working_fcntl_h],
+    [*O_NOFOLLOW* | *no], [gl_val=0], [gl_val=1])
+  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$gl_val],
+    [Define to 1 if O_NOFOLLOW works, 0 otherwise.])
 ])
diff --git a/gl/m4/fcntl.m4 b/gl/m4/fcntl.m4
index 524a99af..08ab936f 100644
--- a/gl/m4/fcntl.m4
+++ b/gl/m4/fcntl.m4
@@ -1,8 +1,10 @@
-# fcntl.m4 serial 11
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# fcntl.m4
+# serial 12
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # For now, this module ensures that fcntl()
 # - supports F_DUPFD correctly
@@ -82,7 +84,7 @@ AC_DEFUN([gl_FUNC_FCNTL],
     esac
 
     dnl Many systems lack F_DUPFD_CLOEXEC.
-    dnl NetBSD 9.0 declares F_DUPFD_CLOEXEC but it works only like F_DUPFD.
+    dnl NetBSD 10.0 declares F_DUPFD_CLOEXEC but it works only like F_DUPFD.
     AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC],
       [gl_cv_func_fcntl_f_dupfd_cloexec],
       [AC_RUN_IFELSE(
diff --git a/gl/m4/fcntl_h.m4 b/gl/m4/fcntl_h.m4
index 68f4e648..1c9f9cce 100644
--- a/gl/m4/fcntl_h.m4
+++ b/gl/m4/fcntl_h.m4
@@ -1,9 +1,12 @@
+# fcntl_h.m4
 # serial 20
-# Configure fcntl.h.
-dnl Copyright (C) 2006-2007, 2009-2023 Free Software Foundation, Inc.
+dnl Copyright (C) 2006-2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+# Configure fcntl.h.
 
 dnl Written by Paul Eggert.
 
diff --git a/gl/m4/fflush.m4 b/gl/m4/fflush.m4
index 3e3c8903..399065b6 100644
--- a/gl/m4/fflush.m4
+++ b/gl/m4/fflush.m4
@@ -1,9 +1,10 @@
-# fflush.m4 serial 18
-
-# Copyright (C) 2007-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# fflush.m4
+# serial 20
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Eric Blake
 
@@ -79,9 +80,10 @@ AC_DEFUN([gl_FUNC_FFLUSH_STDIN],
        [gl_cv_func_fflush_stdin=yes],
        [gl_cv_func_fflush_stdin=no],
        [case "$host_os" in
-                  # Guess no on native Windows.
-          mingw*) gl_cv_func_fflush_stdin="guessing no" ;;
-          *)      gl_cv_func_fflush_stdin=cross ;;
+                             # Guess no on NetBSD, OpenBSD, native Windows.
+          netbsd* | openbsd* | mingw* | windows*)
+                             gl_cv_func_fflush_stdin="guessing no" ;;
+          *)                 gl_cv_func_fflush_stdin=cross ;;
         esac
        ])
      rm conftest.txt
@@ -92,8 +94,8 @@ AC_DEFUN([gl_FUNC_FFLUSH_STDIN],
     *)    gl_func_fflush_stdin='(-1)' ;;
   esac
   AC_DEFINE_UNQUOTED([FUNC_FFLUSH_STDIN], [$gl_func_fflush_stdin],
-    [Define to 1 if fflush is known to work on stdin as per POSIX.1-2008,
-     0 if fflush is known to not work, -1 if unknown.])
+    [Define to 1 if fflush is known to work on stdin as per POSIX.1-2008
+     or later, 0 if fflush is known to not work, -1 if unknown.])
 ])
 
 # Prerequisites of lib/fflush.c.
diff --git a/gl/m4/float_h.m4 b/gl/m4/float_h.m4
index 2f0c9c4e..8580c9c9 100644
--- a/gl/m4/float_h.m4
+++ b/gl/m4/float_h.m4
@@ -1,8 +1,10 @@
-# float_h.m4 serial 13
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# float_h.m4
+# serial 15
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FLOAT_H],
 [
@@ -53,6 +55,31 @@ changequote([,])dnl
       ;;
   esac
 
+  dnl Test for completeness w.r.t. ISO C 23.
+  REPLACE_FLOAT_SNAN=0
+  AC_CACHE_CHECK([whether float.h conforms to ISO C23],
+    [gl_cv_header_float_h_isoc23],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <float.h>
+            int x[] = { FLT_DECIMAL_DIG, DBL_DECIMAL_DIG, LDBL_DECIMAL_DIG };
+            float maxf = FLT_NORM_MAX;
+            double maxd = DBL_NORM_MAX;
+            long double maxl = LDBL_NORM_MAX;
+          ]],
+          [[float sf = FLT_SNAN;
+            double sd = DBL_SNAN;
+            long double sl = LDBL_SNAN;
+            return (sf != 0) + (sd != 0) + (sl != 0);
+          ]])],
+       [gl_cv_header_float_h_isoc23=yes],
+       [gl_cv_header_float_h_isoc23=no])
+    ])
+  if test $gl_cv_header_float_h_isoc23 != yes; then
+    GL_GENERATE_FLOAT_H=true
+    REPLACE_FLOAT_SNAN=1
+  fi
+
   dnl Test against glibc-2.7 Linux/SPARC64 bug.
   REPLACE_ITOLD=0
   AC_CACHE_CHECK([whether conversion from 'int' to 'long double' works],
@@ -84,9 +111,11 @@ int main ()
                [gl_cv_func_itold_works="guessing no"],
                [gl_cv_func_itold_works="guessing yes"])
              ;;
-                   # Guess yes on native Windows.
-           mingw*) gl_cv_func_itold_works="guessing yes" ;;
-           *)      gl_cv_func_itold_works="guessing yes" ;;
+             # Guess yes on native Windows.
+           mingw* | windows*)
+             gl_cv_func_itold_works="guessing yes" ;;
+           *)
+             gl_cv_func_itold_works="guessing yes" ;;
          esac
         ])
     ])
diff --git a/gl/m4/floorf.m4 b/gl/m4/floorf.m4
index c49ffa6b..cb75fce9 100644
--- a/gl/m4/floorf.m4
+++ b/gl/m4/floorf.m4
@@ -1,8 +1,10 @@
-# floorf.m4 serial 18
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# floorf.m4
+# serial 21
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_FLOORF],
 [
@@ -26,7 +28,7 @@ AC_DEFUN([gl_FUNC_FLOORF],
         AC_CACHE_CHECK([whether floorf works according to ISO C 99 with IEC 60559],
           [gl_cv_func_floorf_ieee],
           [
-            save_LIBS="$LIBS"
+            saved_LIBS="$LIBS"
             LIBS="$LIBS $FLOORF_LIBM"
             AC_RUN_IFELSE(
               [AC_LANG_SOURCE([[
@@ -49,17 +51,17 @@ int main (int argc, char *argv[])
               [gl_cv_func_floorf_ieee=yes],
               [gl_cv_func_floorf_ieee=no],
               [case "$host_os" in
-                                # Guess yes on glibc systems.
-                 *-gnu* | gnu*) gl_cv_func_floorf_ieee="guessing yes" ;;
-                                # Guess yes on musl systems.
-                 *-musl*)       gl_cv_func_floorf_ieee="guessing yes" ;;
-                                # Guess yes on native Windows.
-                 mingw*)        gl_cv_func_floorf_ieee="guessing yes" ;;
-                                # If we don't know, obey --enable-cross-guesses.
-                 *)             gl_cv_func_floorf_ieee="$gl_cross_guess_normal" ;;
+                                     # Guess yes on glibc systems.
+                 *-gnu* | gnu*)      gl_cv_func_floorf_ieee="guessing yes" ;;
+                                     # Guess yes on musl systems.
+                 *-musl* | midipix*) gl_cv_func_floorf_ieee="guessing yes" ;;
+                                     # Guess yes on native Windows.
+                 mingw* | windows*)  gl_cv_func_floorf_ieee="guessing yes" ;;
+                                     # If we don't know, obey --enable-cross-guesses.
+                 *)                  gl_cv_func_floorf_ieee="$gl_cross_guess_normal" ;;
                esac
               ])
-            LIBS="$save_LIBS"
+            LIBS="$saved_LIBS"
           ])
         case "$gl_cv_func_floorf_ieee" in
           *yes) ;;
@@ -94,7 +96,7 @@ AC_DEFUN([gl_FUNC_FLOORF_LIBS],
          [[x = funcptr(x) + floorf(x);]])],
       [gl_cv_func_floorf_libm=])
     if test "$gl_cv_func_floorf_libm" = "?"; then
-      save_LIBS="$LIBS"
+      saved_LIBS="$LIBS"
       LIBS="$LIBS -lm"
       AC_LINK_IFELSE(
         [AC_LANG_PROGRAM(
@@ -106,7 +108,7 @@ AC_DEFUN([gl_FUNC_FLOORF_LIBS],
              float x;]],
            [[x = funcptr(x) + floorf(x);]])],
         [gl_cv_func_floorf_libm="-lm"])
-      LIBS="$save_LIBS"
+      LIBS="$saved_LIBS"
     fi
   ])
   FLOORF_LIBM="$gl_cv_func_floorf_libm"
diff --git a/gl/m4/fopen.m4 b/gl/m4/fopen.m4
index 9c39ff72..e27b3270 100644
--- a/gl/m4/fopen.m4
+++ b/gl/m4/fopen.m4
@@ -1,15 +1,17 @@
-# fopen.m4 serial 13
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# fopen.m4
+# serial 16
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-AC_DEFUN([gl_FUNC_FOPEN],
+AC_DEFUN([gl_FUNC_FOPEN_ITSELF],
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST])
   case "$host_os" in
-    mingw* | pw*)
+    mingw* | windows* | pw*)
       dnl Replace fopen, for handling of "/dev/null".
       REPLACE_FOPEN=1
       dnl fopen on mingw also has the trailing slash bug.
@@ -58,6 +60,15 @@ changequote([,])dnl
   esac
 ])
 
+AC_DEFUN([gl_FUNC_FOPEN],
+[
+  AC_REQUIRE([gl_FUNC_FOPEN_ITSELF])
+  AC_REQUIRE([gl_FUNC_FCLOSE])
+  if test $REPLACE_FCLOSE = 1; then
+    REPLACE_FOPEN=1
+  fi
+])
+
 AC_DEFUN([gl_FUNC_FOPEN_GNU],
 [
   AC_REQUIRE([gl_FUNC_FOPEN])
@@ -87,7 +98,7 @@ int main ()
        [gl_cv_func_fopen_mode_x=no],
        [case "$host_os" in
           # Guess yes on glibc and musl systems.
-          linux*-gnu* | gnu* | kfreebsd*-gnu | *-musl*)
+          linux*-gnu* | gnu* | kfreebsd*-gnu | *-musl* | midipix*)
             gl_cv_func_fopen_mode_x="guessing yes" ;;
           # If we don't know, obey --enable-cross-guesses.
           *)
@@ -124,10 +135,10 @@ int main ()
        [gl_cv_func_fopen_mode_e=no],
        [case "$host_os" in
           # Guess yes on glibc and musl systems.
-          linux*-gnu* | gnu* | kfreebsd*-gnu | *-musl*)
+          linux*-gnu* | gnu* | kfreebsd*-gnu | *-musl* | midipix*)
             gl_cv_func_fopen_mode_e="guessing yes" ;;
           # Guess no on native Windows.
-          mingw*)
+          mingw* | windows*)
             gl_cv_func_fopen_mode_e="guessing no" ;;
           # If we don't know, obey --enable-cross-guesses.
           *)
diff --git a/gl/m4/fpurge.m4 b/gl/m4/fpurge.m4
index b365409d..408a2579 100644
--- a/gl/m4/fpurge.m4
+++ b/gl/m4/fpurge.m4
@@ -1,64 +1,65 @@
-# fpurge.m4 serial 12
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# fpurge.m4
+# serial 16
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_FPURGE],
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
-  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([fpurge])
-  AC_CHECK_FUNCS_ONCE([__fpurge])
+  gl_CHECK_FUNCS_ANDROID([__fpurge], [[#include <stdio_ext.h>]])
   AC_CHECK_DECLS([fpurge], , , [[#include <stdio.h>]])
-  if test "x$ac_cv_func_fpurge" = xyes; then
+  if test $ac_cv_func_fpurge = yes; then
     HAVE_FPURGE=1
     # Detect BSD bug.  Only cygwin 1.7 and musl are known to be immune.
     AC_CACHE_CHECK([whether fpurge works], [gl_cv_func_fpurge_works],
-      [AC_RUN_IFELSE(
-         [AC_LANG_PROGRAM(
-            [[#include <stdio.h>
-]],
-            [[FILE *f = fopen ("conftest.txt", "w+");
-              if (!f)
-                return 1;
-              if (fputc ('a', f) != 'a')
-                { fclose (f); return 2; }
-              rewind (f);
-              if (fgetc (f) != 'a')
-                { fclose (f); return 3; }
-              if (fgetc (f) != EOF)
-                { fclose (f); return 4; }
-              if (fpurge (f) != 0)
-                { fclose (f); return 5; }
-              if (putc ('b', f) != 'b')
-                { fclose (f); return 6; }
-              if (fclose (f) != 0)
-                return 7;
-              if ((f = fopen ("conftest.txt", "r")) == NULL)
-                return 8;
-              if (fgetc (f) != 'a')
-                { fclose (f); return 9; }
-              if (fgetc (f) != 'b')
-                { fclose (f); return 10; }
-              if (fgetc (f) != EOF)
-                { fclose (f); return 11; }
-              if (fclose (f) != 0)
-                return 12;
-              if (remove ("conftest.txt") != 0)
-                return 13;
-              return 0;
-            ]])],
-         [gl_cv_func_fpurge_works=yes],
-         [gl_cv_func_fpurge_works=no],
-         [case "$host_os" in
-                     # Guess yes on musl systems.
-            *-musl*) gl_cv_func_fpurge_works="guessing yes" ;;
-                     # Otherwise obey --enable-cross-guesses.
-            *)       gl_cv_func_fpurge_works="$gl_cross_guess_normal" ;;
-          esac
-         ])
+      [if test $ac_cv_have_decl_fpurge = yes; then
+         AC_RUN_IFELSE(
+           [AC_LANG_PROGRAM(
+              [[#include <stdio.h>
+              ]],
+              [[FILE *f = fopen ("conftest.txt", "w+");
+                if (!f)
+                  return 1;
+                if (fputc ('a', f) != 'a')
+                  { fclose (f); return 2; }
+                rewind (f);
+                if (fgetc (f) != 'a')
+                  { fclose (f); return 3; }
+                if (fgetc (f) != EOF)
+                  { fclose (f); return 4; }
+                if (fpurge (f) != 0)
+                  { fclose (f); return 5; }
+                if (putc ('b', f) != 'b')
+                  { fclose (f); return 6; }
+                if (fclose (f) != 0)
+                  return 7;
+                if ((f = fopen ("conftest.txt", "r")) == NULL)
+                  return 8;
+                if (fgetc (f) != 'a')
+                  { fclose (f); return 9; }
+                if (fgetc (f) != 'b')
+                  { fclose (f); return 10; }
+                if (fgetc (f) != EOF)
+                  { fclose (f); return 11; }
+                if (fclose (f) != 0)
+                  return 12;
+                if (remove ("conftest.txt") != 0)
+                  return 13;
+                return 0;
+              ]])],
+           [gl_cv_func_fpurge_works=yes],
+           [gl_cv_func_fpurge_works=no],
+           [# Obey --enable-cross-guesses.
+            gl_cv_func_fpurge_works="$gl_cross_guess_normal"
+           ])
+       else
+         gl_cv_func_fpurge_works=no
+       fi
       ])
     case "$gl_cv_func_fpurge_works" in
       *yes) ;;
diff --git a/gl/m4/freading.m4 b/gl/m4/freading.m4
index 35333369..373d2bff 100644
--- a/gl/m4/freading.m4
+++ b/gl/m4/freading.m4
@@ -1,11 +1,16 @@
-# freading.m4 serial 2
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# freading.m4
+# serial 3
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_FREADING],
 [
   AC_CHECK_HEADERS_ONCE([stdio_ext.h])
-  AC_CHECK_FUNCS_ONCE([__freading])
+  gl_CHECK_FUNCS_ANDROID([__freading],
+    [[#include <stdio.h>
+      #include <stdio_ext.h>
+    ]])
 ])
diff --git a/gl/m4/free.m4 b/gl/m4/free.m4
index 0389dea3..485d8243 100644
--- a/gl/m4/free.m4
+++ b/gl/m4/free.m4
@@ -1,8 +1,10 @@
-# free.m4 serial 6
-# Copyright (C) 2003-2005, 2009-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# free.m4
+# serial 6
+dnl Copyright (C) 2003-2005, 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # Written by Paul Eggert and Bruno Haible.
 
diff --git a/gl/m4/fseek.m4 b/gl/m4/fseek.m4
index c5fe688c..ce728f60 100644
--- a/gl/m4/fseek.m4
+++ b/gl/m4/fseek.m4
@@ -1,8 +1,10 @@
-# fseek.m4 serial 4
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# fseek.m4
+# serial 4
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_FSEEK],
 [
diff --git a/gl/m4/fseeko.m4 b/gl/m4/fseeko.m4
index 05ee06bc..c093d399 100644
--- a/gl/m4/fseeko.m4
+++ b/gl/m4/fseeko.m4
@@ -1,8 +1,10 @@
-# fseeko.m4 serial 20
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# fseeko.m4
+# serial 21
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_FSEEKO],
 [
@@ -68,6 +70,10 @@ AC_DEFUN([gl_STDIN_LARGE_OFFSET],
 # Prerequisites of lib/fseeko.c.
 AC_DEFUN([gl_PREREQ_FSEEKO],
 [
+  if test $gl_cv_func_fseeko != no; then
+    AC_DEFINE([HAVE_FSEEKO], [1],
+      [Define to 1 if the system has the fseeko function.])
+  fi
   dnl Native Windows has the function _fseeki64. mingw hides it in some
   dnl circumstances, but mingw64 makes it usable again.
   AC_CHECK_FUNCS([_fseeki64])
diff --git a/gl/m4/fseterr.m4 b/gl/m4/fseterr.m4
new file mode 100644
index 00000000..3a94c288
--- /dev/null
+++ b/gl/m4/fseterr.m4
@@ -0,0 +1,15 @@
+# fseterr.m4
+# serial 2
+dnl Copyright (C) 2012-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_FSETERR],
+[
+  gl_CHECK_FUNCS_ANDROID([__fseterr],
+    [[#include <stdio.h>
+      #include <stdio_ext.h>
+    ]])
+])
diff --git a/gl/m4/fstat.m4 b/gl/m4/fstat.m4
index 7cb2edb0..e89bbc32 100644
--- a/gl/m4/fstat.m4
+++ b/gl/m4/fstat.m4
@@ -1,8 +1,10 @@
-# fstat.m4 serial 8
-dnl Copyright (C) 2011-2023 Free Software Foundation, Inc.
+# fstat.m4
+# serial 10
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_FSTAT],
 [
@@ -10,10 +12,10 @@ AC_DEFUN([gl_FUNC_FSTAT],
   AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
 
   case "$host_os" in
-    mingw* | solaris*)
+    darwin* | mingw* | windows* | solaris*)
+      dnl macOS and Solaris stat can return a negative tv_nsec.
       dnl On MinGW, the original stat() returns st_atime, st_mtime,
       dnl st_ctime values that are affected by the time zone.
-      dnl Solaris stat can return a negative tv_nsec.
       REPLACE_FSTAT=1
       ;;
   esac
diff --git a/gl/m4/fstypename.m4 b/gl/m4/fstypename.m4
index f65c459f..4407b765 100644
--- a/gl/m4/fstypename.m4
+++ b/gl/m4/fstypename.m4
@@ -1,4 +1,11 @@
-#serial 6
+# fstypename.m4
+# serial 6
+dnl Copyright (C) 1998-1999, 2001, 2004, 2006, 2009-2025 Free Software
+dnl Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Jim Meyering.
 dnl
@@ -6,12 +13,6 @@ dnl See if struct statfs has the f_fstypename member.
 dnl If so, define HAVE_STRUCT_STATFS_F_FSTYPENAME.
 dnl
 
-# Copyright (C) 1998-1999, 2001, 2004, 2006, 2009-2023 Free Software
-# Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
-
 AC_DEFUN([gl_FSTYPENAME],
 [
   AC_CHECK_MEMBERS([struct statfs.f_fstypename],,,
diff --git a/gl/m4/fsusage.m4 b/gl/m4/fsusage.m4
index 88f3ca81..bb7b6e43 100644
--- a/gl/m4/fsusage.m4
+++ b/gl/m4/fsusage.m4
@@ -1,11 +1,13 @@
+# fsusage.m4
 # serial 35
-# Obtaining file system usage information.
+dnl Copyright (C) 1997-1998, 2000-2001, 2003-2025 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# Copyright (C) 1997-1998, 2000-2001, 2003-2023 Free Software Foundation, Inc.
-#
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# Obtaining file system usage information.
 
 # Written by Jim Meyering.
 
@@ -269,7 +271,7 @@ int check_f_blocks_size[sizeof fsd.f_blocks * CHAR_BIT <= 32 ? -1 : 1];
 
 # Check for SunOS statfs brokenness wrt partitions 2GB and larger.
 # If <sys/vfs.h> exists and struct statfs has a member named f_spare,
-# enable the work-around code in fsusage.c.
+# enable the workaround code in fsusage.c.
 AC_DEFUN([gl_STATFS_TRUNCATES],
 [
   AC_CACHE_CHECK([for statfs that truncates block counts],
diff --git a/gl/m4/ftell.m4 b/gl/m4/ftell.m4
index 79f1aaf2..d5610b70 100644
--- a/gl/m4/ftell.m4
+++ b/gl/m4/ftell.m4
@@ -1,8 +1,10 @@
-# ftell.m4 serial 3
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# ftell.m4
+# serial 3
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_FTELL],
 [
diff --git a/gl/m4/ftello.m4 b/gl/m4/ftello.m4
index 4901b168..35d30f98 100644
--- a/gl/m4/ftello.m4
+++ b/gl/m4/ftello.m4
@@ -1,8 +1,10 @@
-# ftello.m4 serial 14
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# ftello.m4
+# serial 17
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_FTELLO],
 [
@@ -37,13 +39,24 @@ AC_DEFUN([gl_FUNC_FTELLO],
     if test $gl_cv_var_stdin_large_offset = no; then
       REPLACE_FTELLO=1
     fi
+    AC_REQUIRE([AC_CANONICAL_HOST])
+    if test $REPLACE_FTELLO = 0; then
+      dnl On native Windows, in some circumstances, ftell(), ftello(),
+      dnl fgetpos(), lseek(), _lseeki64() all succeed on devices of type
+      dnl FILE_TYPE_PIPE. However, to match POSIX behaviour, we want
+      dnl ftell(), ftello(), fgetpos(), lseek() to fail when the argument fd
+      dnl designates a pipe. See also
+      dnl https://github.com/python/cpython/issues/78961#issuecomment-1093800325
+      case "$host_os" in
+        mingw* | windows*) REPLACE_FTELLO=1 ;;
+      esac
+    fi
     if test $REPLACE_FTELLO = 0; then
       dnl Detect bug on Solaris.
       dnl ftell and ftello produce incorrect results after putc that followed a
       dnl getc call that reached EOF on Solaris. This is because the _IOREAD
       dnl flag does not get cleared in this case, even though _IOWRT gets set,
       dnl and ftell and ftello look whether the _IOREAD flag is set.
-      AC_REQUIRE([AC_CANONICAL_HOST])
       AC_CACHE_CHECK([whether ftello works],
         [gl_cv_func_ftello_works],
         [
@@ -51,12 +64,12 @@ AC_DEFUN([gl_FUNC_FTELLO],
           dnl be opened.
 changequote(,)dnl
           case "$host_os" in
-                      # Guess no on Solaris.
-            solaris*) gl_cv_func_ftello_works="guessing no" ;;
-                      # Guess yes on native Windows.
-            mingw*)   gl_cv_func_ftello_works="guessing yes" ;;
-                      # Guess yes otherwise.
-            *)        gl_cv_func_ftello_works="guessing yes" ;;
+                               # Guess no on Solaris.
+            solaris*)          gl_cv_func_ftello_works="guessing no" ;;
+                               # Guess yes on native Windows.
+            mingw* | windows*) gl_cv_func_ftello_works="guessing yes" ;;
+                               # Guess yes otherwise.
+            *)                 gl_cv_func_ftello_works="guessing yes" ;;
           esac
 changequote([,])dnl
           AC_RUN_IFELSE(
@@ -145,6 +158,10 @@ main (void)
 # Prerequisites of lib/ftello.c.
 AC_DEFUN([gl_PREREQ_FTELLO],
 [
+  if test $gl_cv_func_ftello != no; then
+    AC_DEFINE([HAVE_FTELLO], [1],
+      [Define to 1 if the system has the ftello function.])
+  fi
   dnl Native Windows has the function _ftelli64. mingw hides it, but mingw64
   dnl makes it usable again.
   AC_CHECK_FUNCS([_ftelli64])
diff --git a/gl/m4/getaddrinfo.m4 b/gl/m4/getaddrinfo.m4
index 15f09ffb..2931d526 100644
--- a/gl/m4/getaddrinfo.m4
+++ b/gl/m4/getaddrinfo.m4
@@ -1,13 +1,16 @@
-# getaddrinfo.m4 serial 34
-dnl Copyright (C) 2004-2023 Free Software Foundation, Inc.
+# getaddrinfo.m4
+# serial 38
+dnl Copyright (C) 2004-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_GETADDRINFO],
 [
   AC_REQUIRE([gl_SYS_SOCKET_H])dnl for HAVE_SYS_SOCKET_H, HAVE_WINSOCK2_H
   AC_REQUIRE([gl_NETDB_H])dnl for HAVE_NETDB_H
+  AC_REQUIRE([AC_CANONICAL_HOST])
   GETADDRINFO_LIB=
   gai_saved_LIBS="$LIBS"
 
@@ -41,7 +44,7 @@ AC_DEFUN([gl_GETADDRINFO],
     AC_CACHE_CHECK([for getaddrinfo in ws2tcpip.h and -lws2_32],
                    gl_cv_w32_getaddrinfo, [
       gl_cv_w32_getaddrinfo=no
-      am_save_LIBS="$LIBS"
+      gl_saved_LIBS="$LIBS"
       LIBS="$LIBS -lws2_32"
       AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 #ifdef HAVE_WS2TCPIP_H
@@ -49,7 +52,7 @@ AC_DEFUN([gl_GETADDRINFO],
 #endif
 #include <stddef.h>
 ]], [[getaddrinfo(NULL, NULL, NULL, NULL);]])], [gl_cv_w32_getaddrinfo=yes])
-      LIBS="$am_save_LIBS"
+      LIBS="$gl_saved_LIBS"
     ])
     if test "$gl_cv_w32_getaddrinfo" = "yes"; then
       GETADDRINFO_LIB="-lws2_32"
@@ -86,6 +89,46 @@ int getaddrinfo (const char *, const char *, const struct addrinfo *, struct add
       HAVE_GETADDRINFO=0
     fi
   fi
+  if test $HAVE_GETADDRINFO != 0; then
+    AC_CACHE_CHECK([whether getaddrinfo supports AI_NUMERICSERV],
+      [gl_cv_func_getaddrinfo_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM([[
+#include <sys/types.h>
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+#ifdef HAVE_WS2TCPIP_H
+#include <ws2tcpip.h>
+#endif
+#include <stddef.h>
+#include <string.h>
+            ]], [[
+              struct addrinfo hints;
+              struct addrinfo *ai;
+              memset (&hints, 0, sizeof (hints));
+              hints.ai_flags = AI_NUMERICSERV;
+              return getaddrinfo ("www.gnu.org", "http", &hints, &ai) != EAI_NONAME;
+            ]])
+         ],
+         [gl_cv_func_getaddrinfo_works=yes],
+         [gl_cv_func_getaddrinfo_works=no],
+         [case "$host_os" in
+                               # Guess no on native Windows.
+            mingw* | windows*) gl_cv_func_getaddrinfo_works="guessing no" ;;
+                               # Guess yes otherwise.
+            *)                 gl_cv_func_getaddrinfo_works="guessing yes" ;;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_getaddrinfo_works" in
+      *yes) ;;
+      *) REPLACE_GETADDRINFO=1 ;;
+    esac
+  fi
   AC_DEFINE_UNQUOTED([HAVE_GETADDRINFO], [$HAVE_GETADDRINFO],
     [Define to 1 if getaddrinfo exists, or to 0 otherwise.])
 
diff --git a/gl/m4/getdelim.m4 b/gl/m4/getdelim.m4
index 9aaed202..63d88306 100644
--- a/gl/m4/getdelim.m4
+++ b/gl/m4/getdelim.m4
@@ -1,10 +1,12 @@
-# getdelim.m4 serial 16
+# getdelim.m4
+# serial 19
 
-dnl Copyright (C) 2005-2007, 2009-2023 Free Software Foundation, Inc.
+dnl Copyright (C) 2005-2007, 2009-2025 Free Software Foundation, Inc.
 dnl
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_PREREQ([2.59])
 
@@ -18,7 +20,7 @@ AC_DEFUN([gl_FUNC_GETDELIM],
 
   AC_CHECK_DECLS_ONCE([getdelim])
 
-  AC_CHECK_FUNCS_ONCE([getdelim])
+  gl_CHECK_FUNCS_ANDROID([getdelim], [[#include <stdio.h>]])
   if test $ac_cv_func_getdelim = yes; then
     HAVE_GETDELIM=1
     dnl Found it in some library.  Verify that it works.
@@ -82,8 +84,8 @@ AC_DEFUN([gl_FUNC_GETDELIM],
                 ],
                 [gl_cv_func_working_getdelim="guessing yes"],
                 [case "$host_os" in
-                   *-musl*) gl_cv_func_working_getdelim="guessing yes" ;;
-                   *)       gl_cv_func_working_getdelim="$gl_cross_guess_normal" ;;
+                   *-musl* | midipix*) gl_cv_func_working_getdelim="guessing yes" ;;
+                   *)                  gl_cv_func_working_getdelim="$gl_cross_guess_normal" ;;
                  esac
                 ])
              ])
@@ -96,6 +98,9 @@ AC_DEFUN([gl_FUNC_GETDELIM],
     esac
   else
     HAVE_GETDELIM=0
+    case "$gl_cv_onwards_func_getdelim" in
+      future*) REPLACE_GETDELIM=1 ;;
+    esac
   fi
 
   if test $ac_cv_have_decl_getdelim = no; then
diff --git a/gl/m4/getdtablesize.m4 b/gl/m4/getdtablesize.m4
index 8bcda905..112c1c4d 100644
--- a/gl/m4/getdtablesize.m4
+++ b/gl/m4/getdtablesize.m4
@@ -1,8 +1,10 @@
-# getdtablesize.m4 serial 8
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# getdtablesize.m4
+# serial 8
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_GETDTABLESIZE],
 [
diff --git a/gl/m4/gethostname.m4 b/gl/m4/gethostname.m4
index 63f5f636..be71ff78 100644
--- a/gl/m4/gethostname.m4
+++ b/gl/m4/gethostname.m4
@@ -1,8 +1,10 @@
-# gethostname.m4 serial 15
-dnl Copyright (C) 2002, 2008-2023 Free Software Foundation, Inc.
+# gethostname.m4
+# serial 16
+dnl Copyright (C) 2002, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # Ensure
 # - the gethostname() function,
@@ -20,7 +22,7 @@ AC_DEFUN([gl_FUNC_GETHOSTNAME],
     AC_CACHE_CHECK([for gethostname in winsock2.h and -lws2_32],
       [gl_cv_w32_gethostname],
       [gl_cv_w32_gethostname=no
-       gl_save_LIBS="$LIBS"
+       gl_saved_LIBS="$LIBS"
        LIBS="$LIBS -lws2_32"
        AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 #ifdef HAVE_WINSOCK2_H
@@ -28,7 +30,7 @@ AC_DEFUN([gl_FUNC_GETHOSTNAME],
 #endif
 #include <stddef.h>
 ]], [[gethostname(NULL, 0);]])], [gl_cv_w32_gethostname=yes])
-       LIBS="$gl_save_LIBS"
+       LIBS="$gl_saved_LIBS"
       ])
     if test "$gl_cv_w32_gethostname" = "yes"; then
       GETHOSTNAME_LIB="-lws2_32"
diff --git a/gl/m4/getline.m4 b/gl/m4/getline.m4
index 03569f06..b97b8011 100644
--- a/gl/m4/getline.m4
+++ b/gl/m4/getline.m4
@@ -1,11 +1,13 @@
-# getline.m4 serial 30
+# getline.m4
+# serial 33
 
-dnl Copyright (C) 1998-2003, 2005-2007, 2009-2023 Free Software Foundation,
+dnl Copyright (C) 1998-2003, 2005-2007, 2009-2025 Free Software Foundation,
 dnl Inc.
 dnl
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_PREREQ([2.59])
 
@@ -23,12 +25,9 @@ AC_DEFUN([gl_FUNC_GETLINE],
 
   AC_CHECK_DECLS_ONCE([getline])
 
-  gl_getline_needs_run_time_check=no
-  AC_CHECK_FUNC([getline],
-                [dnl Found it in some library.  Verify that it works.
-                 gl_getline_needs_run_time_check=yes],
-                [am_cv_func_working_getline=no])
-  if test $gl_getline_needs_run_time_check = yes; then
+  gl_CHECK_FUNCS_ANDROID([getline], [[#include <stdio.h>]])
+  if test $ac_cv_func_getline = yes; then
+    dnl Found it in some library.  Verify that it works.
     AC_CACHE_CHECK([for working getline function],
       [am_cv_func_working_getline],
       [echo fooNbarN | tr -d '\012' | tr N '\012' > conftest.data
@@ -79,12 +78,17 @@ AC_DEFUN([gl_FUNC_GETLINE],
             ],
             [am_cv_func_working_getline="guessing yes"],
             [case "$host_os" in
-               *-musl*) am_cv_func_working_getline="guessing yes" ;;
-               *)       am_cv_func_working_getline="$gl_cross_guess_normal" ;;
+               *-musl* | midipix*) am_cv_func_working_getline="guessing yes" ;;
+               *)                  am_cv_func_working_getline="$gl_cross_guess_normal" ;;
              esac
             ])
          ])
       ])
+  else
+    am_cv_func_working_getline=no
+    case "$gl_cv_onwards_func_getline" in
+      future*) REPLACE_GETLINE=1 ;;
+    esac
   fi
 
   if test $ac_cv_have_decl_getline = no; then
diff --git a/gl/m4/getloadavg.m4 b/gl/m4/getloadavg.m4
index 79e420ba..8ab613db 100644
--- a/gl/m4/getloadavg.m4
+++ b/gl/m4/getloadavg.m4
@@ -1,13 +1,13 @@
-# Check for getloadavg.
-
-# Copyright (C) 1992-1996, 1999-2000, 2002-2003, 2006, 2008-2023 Free Software
-# Foundation, Inc.
+# getloadavg.m4
+# serial 13
+dnl Copyright (C) 1992-1996, 1999-2000, 2002-2003, 2006, 2008-2025 Free
+dnl Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
-
-#serial 10
+# Check for getloadavg.
 
 # Autoconf defines AC_FUNC_GETLOADAVG, but that is obsolescent.
 # New applications should use gl_GETLOADAVG instead.
@@ -20,13 +20,18 @@ AC_DEFUN([gl_GETLOADAVG],
 # Persuade glibc <stdlib.h> to declare getloadavg().
 AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
 
-gl_save_LIBS=$LIBS
+gl_saved_LIBS=$LIBS
 
 # getloadavg is present in libc on glibc >= 2.2, Mac OS X, FreeBSD >= 2.0,
 # NetBSD >= 0.9, OpenBSD >= 2.0, Solaris >= 7.
 HAVE_GETLOADAVG=1
-AC_CHECK_FUNC([getloadavg], [],
-  [gl_func_getloadavg_done=no
+gl_CHECK_FUNCS_ANDROID([getloadavg], [[#include <stdlib.h>]])
+if test $ac_cv_func_getloadavg != yes; then
+   case "$gl_cv_onwards_func_getloadavg" in
+     future*) REPLACE_GETLOADAVG=1 ;;
+   esac
+
+   gl_func_getloadavg_done=no
 
    # Some systems with -lutil have (and need) -lkvm as well, some do not.
    # On Solaris, -lkvm requires nlist from -lelf, so check that first
@@ -73,14 +78,15 @@ AC_CHECK_FUNC([getloadavg], [],
           AC_DEFINE([DGUX], [1], [Define to 1 for DGUX with <sys/dg_sys_info.h>.])
           AC_CHECK_LIB([dgc], [dg_sys_info])])
      fi
-   fi])
+   fi
+fi
 
-if test "x$gl_save_LIBS" = x; then
+if test "x$gl_saved_LIBS" = x; then
   GETLOADAVG_LIBS=$LIBS
 else
-  GETLOADAVG_LIBS=`echo "$LIBS" | sed "s!$gl_save_LIBS!!"`
+  GETLOADAVG_LIBS=`echo "$LIBS" | sed "s!$gl_saved_LIBS!!"`
 fi
-LIBS=$gl_save_LIBS
+LIBS=$gl_saved_LIBS
 
 AC_SUBST([GETLOADAVG_LIBS])dnl
 
diff --git a/gl/m4/getopt.m4 b/gl/m4/getopt.m4
index 7981a095..cb344c15 100644
--- a/gl/m4/getopt.m4
+++ b/gl/m4/getopt.m4
@@ -1,8 +1,10 @@
-# getopt.m4 serial 48
-dnl Copyright (C) 2002-2006, 2008-2023 Free Software Foundation, Inc.
+# getopt.m4
+# serial 50
+dnl Copyright (C) 2002-2006, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # Request a POSIX compliant getopt function.
 AC_DEFUN([gl_FUNC_GETOPT_POSIX],
@@ -76,7 +78,7 @@ AC_DEFUN([gl_GETOPT_CHECK_HEADERS],
   fi
 
   dnl POSIX 2008 does not specify leading '+' behavior, but see
-  dnl http://austingroupbugs.net/view.php?id=191 for a recommendation on
+  dnl https://austingroupbugs.net/view.php?id=191 for a recommendation on
   dnl the next version of POSIX.  For now, we only guarantee leading '+'
   dnl behavior with getopt-gnu.
   if test -z "$gl_replace_getopt"; then
@@ -197,8 +199,8 @@ main ()
           fi
         else
           case "$host_os" in
-            darwin* | aix* | mingw*) gl_cv_func_getopt_posix="guessing no";;
-            *)                       gl_cv_func_getopt_posix="guessing yes";;
+            darwin* | aix* | mingw* | windows*) gl_cv_func_getopt_posix="guessing no";;
+            *)                                  gl_cv_func_getopt_posix="guessing yes";;
           esac
         fi
       ])
@@ -365,14 +367,7 @@ dnl is ambiguous with environment values that contain newlines.
 
 AC_DEFUN([gl_GETOPT_SUBSTITUTE_HEADER],
 [
-  AC_CHECK_HEADERS_ONCE([sys/cdefs.h])
-  if test $ac_cv_header_sys_cdefs_h = yes; then
-    HAVE_SYS_CDEFS_H=1
-  else
-    HAVE_SYS_CDEFS_H=0
-  fi
-  AC_SUBST([HAVE_SYS_CDEFS_H])
-
+  gl_CHECK_HEADER_SYS_CDEFS_H
   AC_DEFINE([__GETOPT_PREFIX], [[rpl_]],
     [Define to rpl_ if the getopt replacement functions and variables
      should be used.])
diff --git a/gl/m4/getprogname.m4 b/gl/m4/getprogname.m4
index b67c527c..90f34c74 100644
--- a/gl/m4/getprogname.m4
+++ b/gl/m4/getprogname.m4
@@ -1,16 +1,34 @@
-# getprogname.m4 - check for getprogname or replacements for it
+# getprogname.m4
+# serial 8
+dnl Copyright (C) 2016-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# Copyright (C) 2016-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
-
-# serial 4
+# Check for getprogname or replacements for it
 
 AC_DEFUN([gl_FUNC_GETPROGNAME],
 [
-  AC_CHECK_FUNCS_ONCE([getprogname getexecname])
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  gl_CHECK_FUNCS_ANDROID([getprogname], [[#include <stdlib.h>]])
+  if test $ac_cv_func_getprogname = no; then
+    HAVE_GETPROGNAME=0
+    case "$gl_cv_onwards_func_getprogname" in
+      future*) REPLACE_GETPROGNAME=1 ;;
+    esac
+  fi
+  AC_CHECK_DECLS([program_invocation_name],
+    [],
+    [HAVE_DECL_PROGRAM_INVOCATION_NAME=0],
+    [[#include <errno.h>]])
+])
+
+AC_DEFUN([gl_PREREQ_GETPROGNAME],
+[
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_CHECK_FUNCS_ONCE([getexecname])
   ac_found=0
   AC_CHECK_DECLS([program_invocation_name], [ac_found=1], [],
     [#include <errno.h>])
diff --git a/gl/m4/gl-openssl.m4 b/gl/m4/gl-openssl.m4
index 7eab4e10..3cfea50f 100644
--- a/gl/m4/gl-openssl.m4
+++ b/gl/m4/gl-openssl.m4
@@ -1,8 +1,10 @@
-# gl-openssl.m4 serial 6
-dnl Copyright (C) 2013-2023 Free Software Foundation, Inc.
+# gl-openssl.m4
+# serial 7
+dnl Copyright (C) 2013-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_SET_CRYPTO_CHECK_DEFAULT],
 [
@@ -39,6 +41,9 @@ AC_DEFUN([gl_CRYPTO_CHECK],
   AC_SUBST([LIB_CRYPTO])
   if test "x$with_openssl" != xno; then
     if test "x$with_openssl" = xauto-gpl-compat; then
+      dnl OpenSSL versions < 3 are under the OpenSSL license, which is not
+      dnl GPL compatible.
+      dnl See <https://www.gnu.org/licenses/license-list.en.html#OpenSSL>.
       AC_CACHE_CHECK([whether openssl is GPL compatible],
                      [gl_cv_openssl_gpl_compat],
         [AC_COMPILE_IFELSE(
diff --git a/gl/m4/gnulib-cache.m4 b/gl/m4/gnulib-cache.m4
index 267f0692..6a6e8593 100644
--- a/gl/m4/gnulib-cache.m4
+++ b/gl/m4/gnulib-cache.m4
@@ -1,4 +1,4 @@
-# Copyright (C) 2002-2023 Free Software Foundation, Inc.
+# Copyright (C) 2002-2025 Free Software Foundation, Inc.
 #
 # This file is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
diff --git a/gl/m4/gnulib-common.m4 b/gl/m4/gnulib-common.m4
index facc3404..034dae69 100644
--- a/gl/m4/gnulib-common.m4
+++ b/gl/m4/gnulib-common.m4
@@ -1,8 +1,10 @@
-# gnulib-common.m4 serial 75a
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# gnulib-common.m4
+# serial 113
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_PREREQ([2.62])
 
@@ -15,43 +17,65 @@ AC_DEFUN([gl_COMMON], [
   AC_REQUIRE([gl_ZZGNULIB])
 ])
 AC_DEFUN([gl_COMMON_BODY], [
+  AH_VERBATIM([0witness],
+[/* Witness that <config.h> has been included.  */
+#define _GL_CONFIG_H_INCLUDED 1
+])
+  dnl Avoid warnings from gcc -Wtrailing-whitespace.
+  dnl This is a temporary workaround until Autoconf fixes it.
+  dnl Test case:
+  dnl empty1=; empty2=; AC_DEFINE_UNQUOTED([FOO], [$empty1$empty2], [...])
+  dnl should produce "#define FOO /**/", not "#define FOO ".
+  AH_TOP([#if defined __GNUC__ && __GNUC__ >= 15 && !defined __clang__
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wtrailing-whitespace"
+#endif
+])
+  AH_BOTTOM([#if defined __GNUC__ && __GNUC__ >= 15 && !defined __clang__
+# pragma GCC diagnostic pop
+#endif
+])
   AH_VERBATIM([_GL_GNUC_PREREQ],
-[/* True if the compiler says it groks GNU C version MAJOR.MINOR.  */
-#if defined __GNUC__ && defined __GNUC_MINOR__
+[/* True if the compiler says it groks GNU C version MAJOR.MINOR.
+    Except that
+      - clang groks GNU C 4.2, even on Windows, where it does not define
+        __GNUC__.
+      - The OpenMandriva-modified clang compiler pretends that it groks
+        GNU C version 13.1, but it doesn't: It does not support
+        __attribute__ ((__malloc__ (f, i))), nor does it support
+        __attribute__ ((__warning__ (message))) on a function redeclaration.
+      - Users can make clang lie as well, through the -fgnuc-version option.  */
+#if defined __GNUC__ && defined __GNUC_MINOR__ && !defined __clang__
 # define _GL_GNUC_PREREQ(major, minor) \
     ((major) < __GNUC__ + ((minor) <= __GNUC_MINOR__))
+#elif defined __clang__
+  /* clang really only groks GNU C 4.2.  */
+# define _GL_GNUC_PREREQ(major, minor) \
+    ((major) < 4 + ((minor) <= 2))
 #else
 # define _GL_GNUC_PREREQ(major, minor) 0
 #endif
 ])
   AH_VERBATIM([_Noreturn],
-[/* The _Noreturn keyword of C11.  */
+[/* The _Noreturn keyword of C11.
+   Do not use [[noreturn]], because with it the syntax
+     extern _Noreturn void func (...);
+   would not be valid; such a declaration would be valid only with 'extern'
+   and '_Noreturn' swapped, or without the 'extern' keyword.  However, some
+   AIX system header files and several gnulib header files use precisely
+   this syntax with 'extern'.  So even though C23 deprecates _Noreturn,
+   it is currently more portable to prefer it to [[noreturn]].
+
+   Also, do not try to work around LLVM bug 59792 (clang 15 or earlier).
+   This rare bug can be worked around by compiling with 'clang -D_Noreturn=',
+   though the workaround may generate many false-alarm warnings.  */
 #ifndef _Noreturn
-# if (defined __cplusplus \
-      && ((201103 <= __cplusplus && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
-          || (defined _MSC_VER && 1900 <= _MSC_VER)) \
-      && 0)
-    /* [[noreturn]] is not practically usable, because with it the syntax
-         extern _Noreturn void func (...);
-       would not be valid; such a declaration would only be valid with 'extern'
-       and '_Noreturn' swapped, or without the 'extern' keyword.  However, some
-       AIX system header files and several gnulib header files use precisely
-       this syntax with 'extern'.  */
-#  define _Noreturn [[noreturn]]
-# elif (defined __clang__ && __clang_major__ < 16 \
-        && defined _GL_WORK_AROUND_LLVM_BUG_59792)
-   /* Compile with -D_GL_WORK_AROUND_LLVM_BUG_59792 to work around
-      that rare LLVM bug, though you may get many false-alarm warnings.  */
-#  define _Noreturn
-# elif ((!defined __cplusplus || defined __clang__) \
-        && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
-            || (!defined __STRICT_ANSI__ \
-                && (_GL_GNUC_PREREQ (4, 7) \
-                    || (defined __apple_build_version__ \
-                        ? 6000000 <= __apple_build_version__ \
-                        : 3 < __clang_major__ + (5 <= __clang_minor__))))))
+# if ((!defined __cplusplus || defined __clang__) \
+      && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0)))
    /* _Noreturn works as-is.  */
 # elif _GL_GNUC_PREREQ (2, 8) || defined __clang__ || 0x5110 <= __SUNPRO_C
+   /* Prefer __attribute__ ((__noreturn__)) to plain _Noreturn even if the
+      latter works, as 'gcc -std=gnu99 -Wpedantic' warns about _Noreturn.  */
 #  define _Noreturn __attribute__ ((__noreturn__))
 # elif 1200 <= (defined _MSC_VER ? _MSC_VER : 0)
 #  define _Noreturn __declspec (noreturn)
@@ -72,50 +96,267 @@ AC_DEFUN([gl_COMMON_BODY], [
 #endif])
   AH_VERBATIM([attribute],
 [/* Attributes.  */
-#if (defined __has_attribute \
-     && (!defined __clang_minor__ \
-         || (defined __apple_build_version__ \
-             ? 6000000 <= __apple_build_version__ \
-             : 3 < __clang_major__ + (5 <= __clang_minor__))))
-# define _GL_HAS_ATTRIBUTE(attr) __has_attribute (__##attr##__)
-#else
-# define _GL_HAS_ATTRIBUTE(attr) _GL_ATTR_##attr
-# define _GL_ATTR_alloc_size _GL_GNUC_PREREQ (4, 3)
-# define _GL_ATTR_always_inline _GL_GNUC_PREREQ (3, 2)
-# define _GL_ATTR_artificial _GL_GNUC_PREREQ (4, 3)
-# define _GL_ATTR_cold _GL_GNUC_PREREQ (4, 3)
-# define _GL_ATTR_const _GL_GNUC_PREREQ (2, 95)
-# define _GL_ATTR_deprecated _GL_GNUC_PREREQ (3, 1)
-# define _GL_ATTR_diagnose_if 0
-# define _GL_ATTR_error _GL_GNUC_PREREQ (4, 3)
-# define _GL_ATTR_externally_visible _GL_GNUC_PREREQ (4, 1)
-# define _GL_ATTR_fallthrough _GL_GNUC_PREREQ (7, 0)
-# define _GL_ATTR_format _GL_GNUC_PREREQ (2, 7)
-# define _GL_ATTR_leaf _GL_GNUC_PREREQ (4, 6)
-# define _GL_ATTR_malloc _GL_GNUC_PREREQ (3, 0)
-# ifdef _ICC
-#  define _GL_ATTR_may_alias 0
+/* Define _GL_HAS_ATTRIBUTE only once, because on FreeBSD, with gcc < 5, if
+   <config.h> gets included once again after <sys/cdefs.h>, __has_attribute(x)
+   expands to 0 always, and redefining _GL_HAS_ATTRIBUTE would turn off all
+   attributes.  */
+#ifndef _GL_HAS_ATTRIBUTE
+# if (defined __has_attribute \
+      && (!defined __clang_minor__ \
+          || (defined __apple_build_version__ \
+              ? 7000000 <= __apple_build_version__ \
+              : 5 <= __clang_major__)))
+#  define _GL_HAS_ATTRIBUTE(attr) __has_attribute (__##attr##__)
 # else
-#  define _GL_ATTR_may_alias _GL_GNUC_PREREQ (3, 3)
+#  define _GL_HAS_ATTRIBUTE(attr) _GL_ATTR_##attr
+/* The following lines list the first GCC version that supports the attribute.
+   Although the lines are not used in GCC 5 and later (as GCC 5 introduced
+   __has_attribute support), list GCC versions 5+ anyway for completeness.  */
+#  define _GL_ATTR_alloc_size _GL_GNUC_PREREQ (4, 3)
+#  define _GL_ATTR_always_inline _GL_GNUC_PREREQ (3, 2)
+#  define _GL_ATTR_artificial _GL_GNUC_PREREQ (4, 3)
+#  define _GL_ATTR_cold _GL_GNUC_PREREQ (4, 3)
+#  define _GL_ATTR_const _GL_GNUC_PREREQ (2, 95)
+#  define _GL_ATTR_deprecated _GL_GNUC_PREREQ (3, 1)
+#  define _GL_ATTR_diagnose_if 0
+#  define _GL_ATTR_error _GL_GNUC_PREREQ (4, 3)
+#  define _GL_ATTR_externally_visible _GL_GNUC_PREREQ (4, 1)
+#  define _GL_ATTR_fallthrough _GL_GNUC_PREREQ (7, 0)
+#  define _GL_ATTR_format _GL_GNUC_PREREQ (2, 7)
+#  define _GL_ATTR_leaf _GL_GNUC_PREREQ (4, 6)
+#  define _GL_ATTR_malloc _GL_GNUC_PREREQ (3, 0)
+#  ifdef _ICC
+#   define _GL_ATTR_may_alias 0
+#  else
+#   define _GL_ATTR_may_alias _GL_GNUC_PREREQ (3, 3)
+#  endif
+#  define _GL_ATTR_noinline _GL_GNUC_PREREQ (3, 1)
+#  define _GL_ATTR_nonnull _GL_GNUC_PREREQ (3, 3)
+#  define _GL_ATTR_nonnull_if_nonzero _GL_GNUC_PREREQ (15, 1)
+#  define _GL_ATTR_nonstring _GL_GNUC_PREREQ (8, 0)
+#  define _GL_ATTR_nothrow _GL_GNUC_PREREQ (3, 3)
+#  define _GL_ATTR_packed _GL_GNUC_PREREQ (2, 7)
+#  define _GL_ATTR_pure _GL_GNUC_PREREQ (2, 96)
+#  define _GL_ATTR_reproducible _GL_GNUC_PREREQ (15, 1)
+#  define _GL_ATTR_returns_nonnull _GL_GNUC_PREREQ (4, 9)
+#  define _GL_ATTR_sentinel _GL_GNUC_PREREQ (4, 0)
+#  define _GL_ATTR_unsequenced _GL_GNUC_PREREQ (15, 1)
+#  define _GL_ATTR_unused _GL_GNUC_PREREQ (2, 7)
+#  define _GL_ATTR_warn_unused_result _GL_GNUC_PREREQ (3, 4)
 # endif
-# define _GL_ATTR_noinline _GL_GNUC_PREREQ (3, 1)
-# define _GL_ATTR_nonnull _GL_GNUC_PREREQ (3, 3)
-# define _GL_ATTR_nonstring _GL_GNUC_PREREQ (8, 0)
-# define _GL_ATTR_nothrow _GL_GNUC_PREREQ (3, 3)
-# define _GL_ATTR_packed _GL_GNUC_PREREQ (2, 7)
-# define _GL_ATTR_pure _GL_GNUC_PREREQ (2, 96)
-# define _GL_ATTR_returns_nonnull _GL_GNUC_PREREQ (4, 9)
-# define _GL_ATTR_sentinel _GL_GNUC_PREREQ (4, 0)
-# define _GL_ATTR_unused _GL_GNUC_PREREQ (2, 7)
-# define _GL_ATTR_warn_unused_result _GL_GNUC_PREREQ (3, 4)
 #endif
 
-/* Disable GCC -Wpedantic if using __has_c_attribute and this is not C23+.  */
-#if (defined __has_c_attribute && _GL_GNUC_PREREQ (4, 6) \
-     && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) <= 201710)
-# pragma GCC diagnostic ignored "-Wpedantic"
+/* Use __has_c_attribute if available.  However, do not use with
+   pre-C23 GCC, which can issue false positives if -Wpedantic.  */
+#if (defined __has_c_attribute \
+     && ! (_GL_GNUC_PREREQ (4, 6) \
+           && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) <= 201710))
+# define _GL_HAVE___HAS_C_ATTRIBUTE 1
+#else
+# define _GL_HAVE___HAS_C_ATTRIBUTE 0
+#endif
+
+/* Attributes in bracket syntax [[...]] vs. attributes in __attribute__((...))
+   syntax, in function declarations.  There are two problems here.
+   (Last tested with gcc/g++ 14 and clang/clang++ 18.)
+
+   1) We want that the _GL_ATTRIBUTE_* can be cumulated on the same declaration
+      in any order.
+      =========================== foo.c = foo.cc ===========================
+      __attribute__ ((__deprecated__)) [[__nodiscard__]] int bar1 (int);
+      [[__nodiscard__]] __attribute__ ((__deprecated__)) int bar2 (int);
+      ======================================================================
+      This gives a syntax error
+        - in C mode with gcc
+          <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108796>, and
+        - in C++ mode with clang++ version < 16, and
+        - in C++ mode, inside extern "C" {}, still in newer clang++ versions
+          <https://github.com/llvm/llvm-project/issues/101990>.
+ */
+/* Define if, in a function declaration, the attributes in bracket syntax
+   [[...]] must come before the attributes in __attribute__((...)) syntax.
+   If this is defined, it is best to avoid the bracket syntax, so that the
+   various _GL_ATTRIBUTE_* can be cumulated on the same declaration in any
+   order.  */
+#ifdef __cplusplus
+# if defined __clang__
+#  define _GL_BRACKET_BEFORE_ATTRIBUTE 1
+# endif
+#else
+# if defined __GNUC__ && !defined __clang__
+#  define _GL_BRACKET_BEFORE_ATTRIBUTE 1
+# endif
 #endif
+/*
+   2) We want that the _GL_ATTRIBUTE_* can be placed in a declaration
+        - without 'extern', in C as well as in C++,
+        - with 'extern', in C,
+        - with 'extern "C"', in C++
+      in the same position.  That is, we don't want to be forced to use a
+      macro which arranges for the attribute to come before 'extern' in
+      one case and after 'extern' in the other case, because such a macro
+      would make the source code of .h files pretty ugly.
+      =========================== foo.c = foo.cc ===========================
+      #ifdef __cplusplus
+      # define CC "C"
+      #else
+      # define CC
+      #endif
+
+      #define ND   [[__nodiscard__]]
+      #define WUR  __attribute__((__warn_unused_result__))
+
+      #ifdef __cplusplus
+      extern "C" {
+      #endif
+                                        // gcc   clang  g++   clang++
+
+      ND int foo (int);
+      int ND foo (int);                 // warn  error  warn  error
+      int foo ND (int);
+      int foo (int) ND;                 // warn  error  warn  error
+
+      WUR int foo (int);
+      int WUR foo (int);
+      int fo1 WUR (int);                // error error  error error
+      int foo (int) WUR;
+
+      #ifdef __cplusplus
+      }
+      #endif
+
+                                        // gcc   clang  g++   clang++
+
+      ND extern CC int foo (int);       //              error error
+      extern CC ND int foo (int);       // error error
+      extern CC int ND foo (int);       // warn  error  warn  error
+      extern CC int foo ND (int);
+      extern CC int foo (int) ND;       // warn  error  warn  error
+
+      WUR extern CC int foo (int);      //              warn
+      extern CC WUR int foo (int);
+      extern CC int WUR foo (int);
+      extern CC int foo WUR (int);      // error error  error error
+      extern CC int foo (int) WUR;
 
+      ND EXTERN_C_FUNC int foo (int);   //              error error
+      EXTERN_C_FUNC ND int foo (int);
+      EXTERN_C_FUNC int ND foo (int);   // warn  error  warn  error
+      EXTERN_C_FUNC int foo ND (int);
+      EXTERN_C_FUNC int foo (int) ND;   // warn  error  warn  error
+
+      WUR EXTERN_C_FUNC int foo (int);  //              warn
+      EXTERN_C_FUNC WUR int foo (int);
+      EXTERN_C_FUNC int WUR foo (int);
+      EXTERN_C_FUNC int fo2 WUR (int);  // error error  error error
+      EXTERN_C_FUNC int foo (int) WUR;
+      ======================================================================
+      So, if we insist on using the 'extern' keyword ('extern CC' idiom):
+        * If _GL_ATTRIBUTE_* expands to bracket syntax [[...]]
+          in both C and C++, there is one available position:
+            - between the function name and the parameter list.
+        * If _GL_ATTRIBUTE_* expands to __attribute__((...)) syntax
+          in both C and C++, there are several available positions:
+            - before the return type,
+            - between return type and function name,
+            - at the end of the declaration.
+        * If _GL_ATTRIBUTE_* expands to bracket syntax [[...]] in C and to
+          __attribute__((...)) syntax in C++, there is no available position:
+          it would need to come before 'extern' in C but after 'extern "C"'
+          in C++.
+        * If _GL_ATTRIBUTE_* expands to __attribute__((...)) syntax in C and
+          to bracket syntax [[...]] in C++, there is one available position:
+            - before the return type.
+      Whereas, if we use the 'EXTERN_C_FUNC' idiom, which conditionally
+      omits the 'extern' keyword:
+        * If _GL_ATTRIBUTE_* expands to bracket syntax [[...]]
+          in both C and C++, there are two available positions:
+            - before the return type,
+            - between the function name and the parameter list.
+        * If _GL_ATTRIBUTE_* expands to __attribute__((...)) syntax
+          in both C and C++, there are several available positions:
+            - before the return type,
+            - between return type and function name,
+            - at the end of the declaration.
+        * If _GL_ATTRIBUTE_* expands to bracket syntax [[...]] in C and to
+          __attribute__((...)) syntax in C++, there is one available position:
+            - before the return type.
+        * If _GL_ATTRIBUTE_* expands to __attribute__((...)) syntax in C and
+          to bracket syntax [[...]] in C++, there is one available position:
+            - before the return type.
+      The best choice is therefore to use the 'EXTERN_C_FUNC' idiom and
+      put the attributes before the return type. This works regardless
+      to what the _GL_ATTRIBUTE_* macros expand.
+ */
+
+/* Attributes in bracket syntax [[...]] vs. attributes in __attribute__((...))
+   syntax, in static/inline function definitions.
+
+   There are similar constraints as for function declarations.  However, here,
+   we cannot omit the storage-class specifier.  Therefore, the following rule
+   applies:
+     * The macros
+         _GL_ATTRIBUTE_CONST
+         _GL_ATTRIBUTE_DEPRECATED
+         _GL_ATTRIBUTE_MAYBE_UNUSED
+         _GL_ATTRIBUTE_NODISCARD
+         _GL_ATTRIBUTE_PURE
+         _GL_ATTRIBUTE_REPRODUCIBLE
+         _GL_ATTRIBUTE_UNSEQUENCED
+       which may expand to bracket syntax [[...]], must come first, before the
+       storage-class specifier.
+     * Other _GL_ATTRIBUTE_* macros, that expand to __attribute__((...)) syntax,
+       are better placed between the storage-class specifier and the return
+       type.
+ */
+
+/* Attributes in bracket syntax [[...]] vs. attributes in __attribute__((...))
+   syntax, in variable declarations.
+
+   At which position can they be placed?
+   (Last tested with gcc/g++ 14 and clang/clang++ 18.)
+
+      =========================== foo.c = foo.cc ===========================
+      #ifdef __cplusplus
+      # define CC "C"
+      #else
+      # define CC
+      #endif
+
+      #define BD   [[__deprecated__]]
+      #define AD   __attribute__ ((__deprecated__))
+
+                              // gcc   clang  g++    clang++
+
+      BD extern CC int var;   //              error  error
+      extern CC BD int var;   // error error
+      extern CC int BD var;   // warn  error  warn   error
+      extern CC int var BD;
+
+      AD extern CC int var;   //              warn
+      extern CC AD int var;
+      extern CC int AD var;
+      extern CC int var AD;
+
+      BD extern CC int z[];   //              error  error
+      extern CC BD int z[];   // error error
+      extern CC int BD z[];   // warn  error  warn   error
+      extern CC int z1 BD [];
+      extern CC int z[] BD;   // warn  error         error
+
+      AD extern CC int z[];   //              warn
+      extern CC AD int z[];
+      extern CC int AD z[];
+      extern CC int z2 AD []; // error error  error  error
+      extern CC int z[] AD;
+      ======================================================================
+
+   * For non-array variables, the only good position is after the variable name,
+     that is, at the end of the declaration.
+   * For array variables, you will need to distinguish C and C++:
+       - In C, before the 'extern' keyword.
+       - In C++, between the 'extern "C"' and the variable's type.
+ */
 ]dnl There is no _GL_ATTRIBUTE_ALIGNED; use stdalign's alignas instead.
 [
 /* _GL_ATTRIBUTE_ALLOC_SIZE ((N)) declares that the Nth argument of the function
@@ -123,7 +364,7 @@ AC_DEFUN([gl_COMMON_BODY], [
    _GL_ATTRIBUTE_ALLOC_SIZE ((M, N)) declares that the Mth argument multiplied
    by the Nth argument of the function is the size of the returned memory block.
  */
-/* Applies to: function, pointer to function, function types.  */
+/* Applies to: functions, pointer to functions, function types.  */
 #ifndef _GL_ATTRIBUTE_ALLOC_SIZE
 # if _GL_HAS_ATTRIBUTE (alloc_size)
 #  define _GL_ATTRIBUTE_ALLOC_SIZE(args) __attribute__ ((__alloc_size__ args))
@@ -134,7 +375,7 @@ AC_DEFUN([gl_COMMON_BODY], [
 
 /* _GL_ATTRIBUTE_ALWAYS_INLINE tells that the compiler should always inline the
    function and report an error if it cannot do so.  */
-/* Applies to: function.  */
+/* Applies to: functions.  */
 #ifndef _GL_ATTRIBUTE_ALWAYS_INLINE
 # if _GL_HAS_ATTRIBUTE (always_inline)
 #  define _GL_ATTRIBUTE_ALWAYS_INLINE __attribute__ ((__always_inline__))
@@ -146,7 +387,7 @@ AC_DEFUN([gl_COMMON_BODY], [
 /* _GL_ATTRIBUTE_ARTIFICIAL declares that the function is not important to show
     in stack traces when debugging.  The compiler should omit the function from
     stack traces.  */
-/* Applies to: function.  */
+/* Applies to: functions.  */
 #ifndef _GL_ATTRIBUTE_ARTIFICIAL
 # if _GL_HAS_ATTRIBUTE (artificial)
 #  define _GL_ATTRIBUTE_ARTIFICIAL __attribute__ ((__artificial__))
@@ -172,18 +413,23 @@ AC_DEFUN([gl_COMMON_BODY], [
 # endif
 #endif
 
-/* _GL_ATTRIBUTE_CONST declares that it is OK for a compiler to omit duplicate
-   calls to the function with the same arguments.
-   This attribute is safe for a function that neither depends on nor affects
-   observable state, and always returns exactly once - e.g., does not loop
-   forever, and does not call longjmp.
-   (This attribute is stricter than _GL_ATTRIBUTE_PURE.)  */
+/* _GL_ATTRIBUTE_CONST declares:
+   It is OK for a compiler to move calls to the function and to omit
+   calls to the function if another call has the same arguments or the
+   result is not used.
+   This attribute is safe for a function that neither depends on
+   nor affects state, and always returns exactly once -
+   e.g., does not raise an exception, call longjmp, or loop forever.
+   (This attribute is stricter than _GL_ATTRIBUTE_PURE because the
+   function cannot observe state.  It is stricter than
+   _GL_ATTRIBUTE_UNSEQUENCED because the function must return exactly
+   once and cannot depend on state addressed by its arguments.)  */
 /* Applies to: functions.  */
 #ifndef _GL_ATTRIBUTE_CONST
 # if _GL_HAS_ATTRIBUTE (const)
 #  define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
 # else
-#  define _GL_ATTRIBUTE_CONST
+#  define _GL_ATTRIBUTE_CONST _GL_ATTRIBUTE_UNSEQUENCED
 # endif
 #endif
 
@@ -223,9 +469,11 @@ AC_DEFUN([gl_COMMON_BODY], [
      - typedef,
    in C++ also: namespace, class, template specialization.  */
 #ifndef _GL_ATTRIBUTE_DEPRECATED
-# ifdef __has_c_attribute
-#  if __has_c_attribute (__deprecated__)
-#   define _GL_ATTRIBUTE_DEPRECATED [[__deprecated__]]
+# ifndef _GL_BRACKET_BEFORE_ATTRIBUTE
+#  if _GL_HAVE___HAS_C_ATTRIBUTE
+#   if __has_c_attribute (__deprecated__)
+#    define _GL_ATTRIBUTE_DEPRECATED [[__deprecated__]]
+#   endif
 #  endif
 # endif
 # if !defined _GL_ATTRIBUTE_DEPRECATED && _GL_HAS_ATTRIBUTE (deprecated)
@@ -271,7 +519,7 @@ AC_DEFUN([gl_COMMON_BODY], [
 /* Applies to: Empty statement (;), inside a 'switch' statement.  */
 /* Always expands to something.  */
 #ifndef _GL_ATTRIBUTE_FALLTHROUGH
-# ifdef __has_c_attribute
+# if _GL_HAVE___HAS_C_ATTRIBUTE
 #  if __has_c_attribute (__fallthrough__)
 #   define _GL_ATTRIBUTE_FALLTHROUGH [[__fallthrough__]]
 #  endif
@@ -351,11 +599,19 @@ AC_DEFUN([gl_COMMON_BODY], [
    in C++ also: class.  */
 /* In C++ and C23, this is spelled [[__maybe_unused__]].
    GCC's syntax is __attribute__ ((__unused__)).
-   clang supports both syntaxes.  */
+   clang supports both syntaxes.  Except that with clang ≥ 6, < 10, in C++ mode,
+   __has_c_attribute (__maybe_unused__) yields true but the use of
+   [[__maybe_unused__]] nevertheless produces a warning.  */
 #ifndef _GL_ATTRIBUTE_MAYBE_UNUSED
-# ifdef __has_c_attribute
-#  if __has_c_attribute (__maybe_unused__)
-#   define _GL_ATTRIBUTE_MAYBE_UNUSED [[__maybe_unused__]]
+# ifndef _GL_BRACKET_BEFORE_ATTRIBUTE
+#  if defined __clang__ && defined __cplusplus
+#   if !defined __apple_build_version__ && __clang_major__ >= 10
+#    define _GL_ATTRIBUTE_MAYBE_UNUSED [[__maybe_unused__]]
+#   endif
+#  elif _GL_HAVE___HAS_C_ATTRIBUTE
+#   if __has_c_attribute (__maybe_unused__)
+#    define _GL_ATTRIBUTE_MAYBE_UNUSED [[__maybe_unused__]]
+#   endif
 #  endif
 # endif
 # ifndef _GL_ATTRIBUTE_MAYBE_UNUSED
@@ -373,9 +629,20 @@ AC_DEFUN([gl_COMMON_BODY], [
    the return value, unless the caller uses something like ignore_value.  */
 /* Applies to: function, enumeration, class.  */
 #ifndef _GL_ATTRIBUTE_NODISCARD
-# ifdef __has_c_attribute
-#  if __has_c_attribute (__nodiscard__)
-#   define _GL_ATTRIBUTE_NODISCARD [[__nodiscard__]]
+# ifndef _GL_BRACKET_BEFORE_ATTRIBUTE
+#  if defined __clang__ && defined __cplusplus
+  /* With clang up to 15.0.6 (at least), in C++ mode, [[__nodiscard__]] produces
+     a warning.
+     The 1000 below means a yet unknown threshold.  When clang++ version X
+     starts supporting [[__nodiscard__]] without warning about it, you can
+     replace the 1000 with X.  */
+#   if __clang_major__ >= 1000
+#    define _GL_ATTRIBUTE_NODISCARD [[__nodiscard__]]
+#   endif
+#  elif _GL_HAVE___HAS_C_ATTRIBUTE
+#   if __has_c_attribute (__nodiscard__)
+#    define _GL_ATTRIBUTE_NODISCARD [[__nodiscard__]]
+#   endif
 #  endif
 # endif
 # if !defined _GL_ATTRIBUTE_NODISCARD && _GL_HAS_ATTRIBUTE (warn_unused_result)
@@ -410,6 +677,17 @@ AC_DEFUN([gl_COMMON_BODY], [
 # endif
 #endif
 
+/* _GL_ATTRIBUTE_NONNULL_IF_NONZERO (NP, NI) declares that the argument NP
+   (a pointer) must not be NULL if the argument NI (an integer) is != 0.  */
+/* Applies to: functions.  */
+#ifndef _GL_ATTRIBUTE_NONNULL_IF_NONZERO
+# if _GL_HAS_ATTRIBUTE (nonnull_if_nonzero)
+#  define _GL_ATTRIBUTE_NONNULL_IF_NONZERO(np, ni) __attribute__ ((__nonnull_if_nonzero__ (np, ni)))
+# else
+#  define _GL_ATTRIBUTE_NONNULL_IF_NONZERO(np, ni)
+# endif
+#endif
+
 /* _GL_ATTRIBUTE_NONSTRING declares that the contents of a character array is
    not meant to be NUL-terminated.  */
 /* Applies to: struct/union members and variables that are arrays of element
@@ -427,11 +705,25 @@ AC_DEFUN([gl_COMMON_BODY], [
 /* _GL_ATTRIBUTE_NOTHROW declares that the function does not throw exceptions.
  */
 /* Applies to: functions.  */
+/* After a function's parameter list, this attribute must come first, before
+   other attributes.  */
 #ifndef _GL_ATTRIBUTE_NOTHROW
-# if _GL_HAS_ATTRIBUTE (nothrow) && !defined __cplusplus
-#  define _GL_ATTRIBUTE_NOTHROW __attribute__ ((__nothrow__))
+# if defined __cplusplus
+#  if _GL_GNUC_PREREQ (2, 8) || __clang_major__ >= 4
+#   if __cplusplus >= 201103L
+#    define _GL_ATTRIBUTE_NOTHROW noexcept (true)
+#   else
+#    define _GL_ATTRIBUTE_NOTHROW throw ()
+#   endif
+#  else
+#   define _GL_ATTRIBUTE_NOTHROW
+#  endif
 # else
-#  define _GL_ATTRIBUTE_NOTHROW
+#  if _GL_HAS_ATTRIBUTE (nothrow)
+#   define _GL_ATTRIBUTE_NOTHROW __attribute__ ((__nothrow__))
+#  else
+#   define _GL_ATTRIBUTE_NOTHROW
+#  endif
 # endif
 #endif
 
@@ -442,25 +734,60 @@ AC_DEFUN([gl_COMMON_BODY], [
 /* Applies to: struct members, struct, union,
    in C++ also: class.  */
 #ifndef _GL_ATTRIBUTE_PACKED
-# if _GL_HAS_ATTRIBUTE (packed)
+/* Oracle Studio 12.6 miscompiles code with __attribute__ ((__packed__)) despite
+   __has_attribute OK.  */
+# if _GL_HAS_ATTRIBUTE (packed) && !defined __SUNPRO_C
 #  define _GL_ATTRIBUTE_PACKED __attribute__ ((__packed__))
 # else
 #  define _GL_ATTRIBUTE_PACKED
 # endif
 #endif
 
-/* _GL_ATTRIBUTE_PURE declares that It is OK for a compiler to omit duplicate
-   calls to the function with the same arguments if observable state is not
-   changed between calls.
-   This attribute is safe for a function that does not affect
-   observable state, and always returns exactly once.
-   (This attribute is looser than _GL_ATTRIBUTE_CONST.)  */
+/* _GL_ATTRIBUTE_PURE declares:
+   It is OK for a compiler to move calls to the function and to omit
+   calls to the function if another call has the same arguments or the
+   result is not used, and if observable state is the same.
+   This attribute is safe for a function that does not affect observable state
+   and always returns exactly once.
+   (This attribute is looser than _GL_ATTRIBUTE_CONST because the function
+   can depend on observable state.  It is stricter than
+   _GL_ATTRIBUTE_REPRODUCIBLE because the function must return exactly
+   once and cannot affect state addressed by its arguments.)  */
 /* Applies to: functions.  */
 #ifndef _GL_ATTRIBUTE_PURE
 # if _GL_HAS_ATTRIBUTE (pure)
 #  define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
 # else
-#  define _GL_ATTRIBUTE_PURE
+#  define _GL_ATTRIBUTE_PURE _GL_ATTRIBUTE_REPRODUCIBLE
+# endif
+#endif
+
+/* _GL_ATTRIBUTE_REPRODUCIBLE declares:
+   It is OK for a compiler to move calls to the function and to omit duplicate
+   calls to the function with the same arguments, so long as the state
+   addressed by its arguments is the same and is updated in time for
+   the rest of the program.
+   This attribute is safe for a function that is effectless and idempotent; see
+   ISO C 23 § 6.7.12.7 for a definition of these terms.
+   (This attribute is looser than _GL_ATTRIBUTE_UNSEQUENCED because
+   the function need not be stateless and idempotent.  It is looser
+   than _GL_ATTRIBUTE_PURE because the function need not return
+   exactly once and can affect state addressed by its arguments.)
+   See also <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2956.htm> and
+   <https://stackoverflow.com/questions/76847905/>.
+   ATTENTION! Efforts are underway to change the meaning of this attribute.
+   See <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3424.htm>.  */
+/* Applies to: functions, pointer to functions, function types.  */
+#ifndef _GL_ATTRIBUTE_REPRODUCIBLE
+/* This may be revisited when gcc and clang support [[reproducible]] or possibly
+   __attribute__ ((__reproducible__)).  */
+# ifndef _GL_BRACKET_BEFORE_ATTRIBUTE
+#  if _GL_HAS_ATTRIBUTE (reproducible)
+#   define _GL_ATTRIBUTE_REPRODUCIBLE [[reproducible]]
+#  endif
+# endif
+# ifndef _GL_ATTRIBUTE_REPRODUCIBLE
+#  define _GL_ATTRIBUTE_REPRODUCIBLE
 # endif
 #endif
 
@@ -488,6 +815,35 @@ AC_DEFUN([gl_COMMON_BODY], [
 # endif
 #endif
 
+/* _GL_ATTRIBUTE_UNSEQUENCED declares:
+   It is OK for a compiler to move calls to the function and to omit duplicate
+   calls to the function with the same arguments, so long as the state
+   addressed by its arguments is the same.
+   This attribute is safe for a function that is effectless, idempotent,
+   stateless, and independent; see ISO C 23 § 6.7.12.7 for a definition of
+   these terms.
+   (This attribute is stricter than _GL_ATTRIBUTE_REPRODUCIBLE because
+   the function must be stateless and independent.  It is looser than
+   _GL_ATTRIBUTE_CONST because the function need not return exactly
+   once and can depend on state addressed by its arguments.)
+   See also <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2956.htm> and
+   <https://stackoverflow.com/questions/76847905/>.
+   ATTENTION! Efforts are underway to change the meaning of this attribute.
+   See <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3424.htm>.  */
+/* Applies to: functions, pointer to functions, function types.  */
+#ifndef _GL_ATTRIBUTE_UNSEQUENCED
+/* This may be revisited when gcc and clang support [[unsequenced]] or possibly
+   __attribute__ ((__unsequenced__)).  */
+# ifndef _GL_BRACKET_BEFORE_ATTRIBUTE
+#  if _GL_HAS_ATTRIBUTE (unsequenced)
+#   define _GL_ATTRIBUTE_UNSEQUENCED [[unsequenced]]
+#  endif
+# endif
+# ifndef _GL_ATTRIBUTE_UNSEQUENCED
+#  define _GL_ATTRIBUTE_UNSEQUENCED
+# endif
+#endif
+
 /* A helper macro.  Don't use it directly.  */
 #ifndef _GL_ATTRIBUTE_UNUSED
 # if _GL_HAS_ATTRIBUTE (unused)
@@ -512,6 +868,47 @@ AC_DEFUN([gl_COMMON_BODY], [
 #  define _GL_UNUSED_LABEL
 # endif
 #endif
+
+/* The following attributes enable detection of multithread-safety problems
+   and resource leaks at compile-time, by clang ≥ 15, when the warning option
+   -Wthread-safety is enabled.  For usage, see
+   <https://clang.llvm.org/docs/ThreadSafetyAnalysis.html>.  */
+#ifndef _GL_ATTRIBUTE_CAPABILITY_TYPE
+# if __clang_major__ >= 15
+#  define _GL_ATTRIBUTE_CAPABILITY_TYPE(concept) \
+     __attribute__ ((__capability__ (concept)))
+# else
+#  define _GL_ATTRIBUTE_CAPABILITY_TYPE(concept)
+# endif
+#endif
+#ifndef _GL_ATTRIBUTE_ACQUIRE_CAPABILITY
+# if __clang_major__ >= 15
+#  define _GL_ATTRIBUTE_ACQUIRE_CAPABILITY(resource) \
+     __attribute__ ((__acquire_capability__ (resource)))
+# else
+#  define _GL_ATTRIBUTE_ACQUIRE_CAPABILITY(resource)
+# endif
+#endif
+#ifndef _GL_ATTRIBUTE_RELEASE_CAPABILITY
+# if __clang_major__ >= 15
+#  define _GL_ATTRIBUTE_RELEASE_CAPABILITY(resource) \
+     __attribute__ ((__release_capability__ (resource)))
+# else
+#  define _GL_ATTRIBUTE_RELEASE_CAPABILITY(resource)
+# endif
+#endif
+])
+  AH_VERBATIM([c_linkage],
+[/* In C++, there is the concept of "language linkage", that encompasses
+    name mangling and function calling conventions.
+    The following macros start and end a block of "C" linkage.  */
+#ifdef __cplusplus
+# define _GL_BEGIN_C_LINKAGE extern "C" {
+# define _GL_END_C_LINKAGE }
+#else
+# define _GL_BEGIN_C_LINKAGE
+# define _GL_END_C_LINKAGE
+#endif
 ])
   AH_VERBATIM([async_safe],
 [/* The _GL_ASYNC_SAFE marker should be attached to functions that are
@@ -550,8 +947,8 @@ AC_DEFUN([gl_COMMON_BODY], [
      -1 if n1 < n2
    The naïve code   (n1 > n2 ? 1 : n1 < n2 ? -1 : 0)  produces a conditional
    jump with nearly all GCC versions up to GCC 10.
-   This variant     (n1 < n2 ? -1 : n1 > n2)  produces a conditional with many
-   GCC versions up to GCC 9.
+   This variant     (n1 < n2 ? -1 : n1 > n2)  produces a conditional jump with
+   many GCC versions up to GCC 9.
    The better code  (n1 > n2) - (n1 < n2)  from Hacker's Delight § 2-9
    avoids conditional jumps in all GCC versions >= 3.4.  */
 #define _GL_CMP(n1, n2) (((n1) > (n2)) - ((n1) < (n2)))
@@ -568,7 +965,7 @@ AC_DEFUN([gl_COMMON_BODY], [
   dnl gl_cross_guess_normal    (to be used when 'yes' is good and 'no' is bad),
   dnl gl_cross_guess_inverted  (to be used when 'no' is good and 'yes' is bad).
   AC_ARG_ENABLE([cross-guesses],
-    [AS_HELP_STRING([--enable-cross-guesses={conservative|risky}],
+    [AS_HELP_STRING([[--enable-cross-guesses={conservative|risky}]],
        [specify policy for cross-compilation guesses])],
     [if test "x$enableval" != xconservative && test "x$enableval" != xrisky; then
        AC_MSG_WARN([invalid argument supplied to --enable-cross-guesses])
@@ -928,7 +1325,7 @@ AC_DEFUN([gl_CC_ALLOW_WARNINGS],
   AC_REQUIRE([AC_PROG_CC])
   AC_CACHE_CHECK([for C compiler option to allow warnings],
     [gl_cv_cc_wallow],
-    [rm -f conftest*
+    [rm -fr conftest*
      echo 'int dummy;' > conftest.c
      AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c 2>conftest1.err]) >/dev/null
      AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -Wno-error -c conftest.c 2>conftest2.err]) >/dev/null
@@ -941,7 +1338,7 @@ AC_DEFUN([gl_CC_ALLOW_WARNINGS],
      else
        gl_cv_cc_wallow=none
      fi
-     rm -f conftest*
+     rm -fr conftest*
     ])
   case "$gl_cv_cc_wallow" in
     none) GL_CFLAG_ALLOW_WARNINGS='' ;;
@@ -959,7 +1356,7 @@ AC_DEFUN([gl_CXX_ALLOW_WARNINGS],
   if test -n "$CXX" && test "$CXX" != no; then
     AC_CACHE_CHECK([for C++ compiler option to allow warnings],
       [gl_cv_cxx_wallow],
-      [rm -f conftest*
+      [rm -fr conftest*
        echo 'int dummy;' > conftest.cc
        AC_TRY_COMMAND([${CXX-c++} $CXXFLAGS $CPPFLAGS -c conftest.cc 2>conftest1.err]) >/dev/null
        AC_TRY_COMMAND([${CXX-c++} $CXXFLAGS $CPPFLAGS -Wno-error -c conftest.cc 2>conftest2.err]) >/dev/null
@@ -972,7 +1369,7 @@ AC_DEFUN([gl_CXX_ALLOW_WARNINGS],
        else
          gl_cv_cxx_wallow=none
        fi
-       rm -f conftest*
+       rm -fr conftest*
       ])
     case "$gl_cv_cxx_wallow" in
       none) GL_CXXFLAG_ALLOW_WARNINGS='' ;;
@@ -1005,14 +1402,16 @@ AC_DEFUN([gl_CC_GNULIB_WARNINGS],
     dnl -Wno-pedantic                         >= 4.8          >= 3.9
     dnl -Wno-sign-compare                     >= 3            >= 3.9
     dnl -Wno-sign-conversion                  >= 4.3          >= 3.9
+    dnl -Wno-tautological-out-of-range-compare  -             >= 3.9
     dnl -Wno-type-limits                      >= 4.3          >= 3.9
     dnl -Wno-undef                            >= 3            >= 3.9
     dnl -Wno-unsuffixed-float-constants       >= 4.5
+    dnl -Wno-unused-const-variable            >= 4.4          >= 3.9
     dnl -Wno-unused-function                  >= 3            >= 3.9
     dnl -Wno-unused-parameter                 >= 3            >= 3.9
     dnl
     cat > conftest.c <<\EOF
-      #if __GNUC__ >= 3 || (__clang_major__ + (__clang_minor__ >= 9) > 3)
+      #if (__GNUC__ >= 3 && !defined __clang__) || (__clang_major__ + (__clang_minor__ >= 9) > 3)
       -Wno-cast-qual
       -Wno-conversion
       -Wno-float-equal
@@ -1021,20 +1420,26 @@ AC_DEFUN([gl_CC_GNULIB_WARNINGS],
       -Wno-unused-function
       -Wno-unused-parameter
       #endif
-      #if __GNUC__ + (__GNUC_MINOR__ >= 9) > 4 || (__clang_major__ + (__clang_minor__ >= 9) > 3)
+      #if (__GNUC__ + (__GNUC_MINOR__ >= 9) > 4 && !defined __clang__) || (__clang_major__ + (__clang_minor__ >= 9) > 3)
       -Wno-float-conversion
       #endif
-      #if __GNUC__ >= 7 || (__clang_major__ + (__clang_minor__ >= 9) > 3)
+      #if (__GNUC__ >= 7 && !defined __clang__) || (__clang_major__ + (__clang_minor__ >= 9) > 3)
       -Wimplicit-fallthrough
       #endif
-      #if __GNUC__ + (__GNUC_MINOR__ >= 8) > 4 || (__clang_major__ + (__clang_minor__ >= 9) > 3)
+      #if (__GNUC__ + (__GNUC_MINOR__ >= 8) > 4 && !defined __clang__) || (__clang_major__ + (__clang_minor__ >= 9) > 3)
       -Wno-pedantic
       #endif
-      #if __GNUC__ + (__GNUC_MINOR__ >= 3) > 4 || (__clang_major__ + (__clang_minor__ >= 9) > 3)
+      #if 3 < __clang_major__ + (9 <= __clang_minor__)
+      -Wno-tautological-constant-out-of-range-compare
+      #endif
+      #if (__GNUC__ + (__GNUC_MINOR__ >= 3) > 4 && !defined __clang__) || (__clang_major__ + (__clang_minor__ >= 9) > 3)
       -Wno-sign-conversion
       -Wno-type-limits
       #endif
-      #if __GNUC__ + (__GNUC_MINOR__ >= 5) > 4
+      #if (__GNUC__ + (__GNUC_MINOR__ >= 4) > 4 && !defined __clang__) || (__clang_major__ + (__clang_minor__ >= 9) > 3)
+      -Wno-unused-const-variable
+      #endif
+      #if (__GNUC__ + (__GNUC_MINOR__ >= 5) > 4 && !defined __clang__)
       -Wno-unsuffixed-float-constants
       #endif
 EOF
@@ -1080,6 +1485,250 @@ AC_DEFUN([gl_CONDITIONAL_HEADER],
   m4_popdef([gl_header_name])
 ])
 
+dnl Preparations for gl_CHECK_FUNCS_MACOS.
+AC_DEFUN([gl_PREPARE_CHECK_FUNCS_MACOS],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_COMPILER_CLANG])
+  AC_CACHE_CHECK([for compiler option needed when checking for future declarations],
+    [gl_cv_compiler_check_future_option],
+    [case "$host_os" in
+       dnl This is only needed on macOS.
+       darwin*)
+         if test $gl_cv_compiler_clang = yes; then
+           dnl Test whether the compiler supports the option
+           dnl '-Werror=unguarded-availability-new'.
+           saved_ac_compile="$ac_compile"
+           ac_compile="$ac_compile -Werror=unguarded-availability-new"
+           AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]],[[]])],
+             [gl_cv_compiler_check_future_option='-Werror=unguarded-availability-new'],
+             [gl_cv_compiler_check_future_option=none])
+           ac_compile="$saved_ac_compile"
+         else
+           gl_cv_compiler_check_future_option=none
+         fi
+         ;;
+       *) gl_cv_compiler_check_future_option=none ;;
+     esac
+    ])
+])
+
+dnl Pieces of the expansion of
+dnl gl_CHECK_FUNCS_ANDROID
+dnl gl_CHECK_FUNCS_MACOS
+dnl gl_CHECK_FUNCS_ANDROID_MACOS
+
+AC_DEFUN([gl_CHECK_FUNCS_DEFAULT_CASE],
+[
+         *)
+           AC_CHECK_FUNC([$1])
+           [gl_cv_onwards_func_][$1]=$[ac_cv_func_][$1]
+           ;;
+])
+
+AC_DEFUN([gl_CHECK_FUNCS_CASE_FOR_ANDROID],
+[
+         linux*-android*)
+           AC_CHECK_DECL([$1], , , [$2])
+           if test $[ac_cv_have_decl_][$1] = yes; then
+             AC_CHECK_FUNC([[$1]])
+             if test $[ac_cv_func_][$1] = yes; then
+               [gl_cv_onwards_func_][$1]=yes
+             else
+               dnl The function is declared but does not exist. This should not
+               dnl happen normally. But anyway, we know that a future version
+               dnl of Android will have the function.
+               [gl_cv_onwards_func_][$1]='future OS version'
+             fi
+           else
+             [gl_cv_onwards_func_][$1]='future OS version'
+           fi
+           ;;
+])
+
+AC_DEFUN([gl_CHECK_FUNCS_CASE_FOR_MACOS],
+[
+         darwin*)
+           if test "x$gl_cv_compiler_check_future_option" != "xnone"; then
+             dnl Use a compile test, not a link test.
+             saved_ac_compile="$ac_compile"
+             ac_compile="$ac_compile $gl_cv_compiler_check_future_option"
+             saved_ac_compile_for_check_decl="$ac_compile_for_check_decl"
+             ac_compile_for_check_decl="$ac_compile_for_check_decl $gl_cv_compiler_check_future_option"
+             unset [ac_cv_have_decl_][$1]
+             AC_CHECK_DECL([$1], , , [$2])
+             ac_compile="$saved_ac_compile"
+             ac_compile_for_check_decl="$saved_ac_compile_for_check_decl"
+             [ac_cv_func_][$1]="$[ac_cv_have_decl_][$1]"
+             if test $[ac_cv_func_][$1] = yes; then
+               [gl_cv_onwards_func_][$1]=yes
+             else
+               dnl This is a bit complicated, because here we need the behaviour
+               dnl of AC_CHECK_DECL before the
+               dnl commit e1bbc9b93cdff61d70719c224b37970e065008bb (2025-05-26).
+               [ac_cv_have_decl_][$1][_saved]="$[ac_cv_have_decl_][$1]"
+               unset [ac_cv_have_decl_][$1]
+               ac_c_future_darwin_options_saved="$ac_c_future_darwin_options"
+               ac_cxx_future_darwin_options_saved="$ac_cxx_future_darwin_options"
+               ac_c_future_darwin_options=
+               ac_cxx_future_darwin_options=
+               AC_CHECK_DECL([$1], , , [$2])
+               ac_c_future_darwin_options="$ac_c_future_darwin_options_saved"
+               ac_cxx_future_darwin_options="$ac_cxx_future_darwin_options_saved"
+               if test $[ac_cv_have_decl_][$1] = yes; then
+                 [gl_cv_onwards_func_][$1]='future OS version'
+               else
+                 [gl_cv_onwards_func_][$1]=no
+               fi
+               [ac_cv_have_decl_][$1]="$[ac_cv_have_decl_][$1][_saved]"
+               unset [ac_cv_have_decl_][$1][_saved]
+             fi
+           else
+             AC_CHECK_FUNC([$1])
+             [gl_cv_onwards_func_][$1]=$[ac_cv_func_][$1]
+           fi
+           ;;
+])
+
+AC_DEFUN([gl_CHECK_FUNCS_SET_RESULTS],
+[
+  case "$[gl_cv_onwards_func_][$1]" in
+    future*) [ac_cv_func_][$1]=no ;;
+    *)       [ac_cv_func_][$1]=$[gl_cv_onwards_func_][$1] ;;
+  esac
+  if test $[ac_cv_func_][$1] = yes; then
+    AC_DEFINE([HAVE_]m4_translit([[$1]],
+                                 [abcdefghijklmnopqrstuvwxyz],
+                                 [ABCDEFGHIJKLMNOPQRSTUVWXYZ]),
+              [1], [Define to 1 if you have the `$1' function.])
+  fi
+])
+
+dnl gl_CHECK_FUNCS_ANDROID([func], [[#include <foo.h>]])
+dnl is like AC_CHECK_FUNCS([func]), taking into account a portability problem
+dnl on Android.
+dnl
+dnl When code is compiled on Android, it is in the context of a certain
+dnl "Android API level", which indicates the minimum version of Android on
+dnl which the app can be installed. In other words, you don't compile for a
+dnl specific version of Android. You compile for all versions of Android,
+dnl onwards from the given API level.
+dnl Thus, the question "does the OS have the function func" has three possible
+dnl answers:
+dnl   - yes, in all versions starting from the given API level,
+dnl   - no, in no version,
+dnl   - not in the given API level, but in a later version of Android.
+dnl
+dnl In detail, this works as follows:
+dnl If func was added to Android API level, say, 28, then the libc.so has the
+dnl symbol func always, whereas the header file <foo.h> declares func
+dnl conditionally:
+dnl   #if __ANDROID_API__ >= 28
+dnl   ... func (...) __INTRODUCED_IN(28);
+dnl   #endif
+dnl Thus, when compiling with "clang -target armv7a-unknown-linux-android28",
+dnl the function func is declared and exists in libc.
+dnl Whereas when compiling with "clang -target armv7a-unknown-linux-android27",
+dnl the function func is not declared but exists in libc.
+dnl
+dnl This macro sets two variables:
+dnl   - gl_cv_onwards_func_<func>   to yes / no / "future OS version"
+dnl   - ac_cv_func_<func>           to yes / no / no
+dnl The first variable allows distinguishing all three cases.
+dnl The second variable is set, so that an invocation
+dnl   gl_CHECK_FUNCS_ANDROID([func], [[#include <foo.h>]])
+dnl can be used as a drop-in replacement for
+dnl   AC_CHECK_FUNCS([func]).
+AC_DEFUN([gl_CHECK_FUNCS_ANDROID],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CACHE_CHECK([for [$1]],
+    [[gl_cv_onwards_func_][$1]],
+    [gl_SILENT([
+       case "$host_os" in
+         gl_CHECK_FUNCS_CASE_FOR_ANDROID([$1], [$2])
+         gl_CHECK_FUNCS_DEFAULT_CASE([$1])
+       esac
+      ])
+    ])
+  gl_CHECK_FUNCS_SET_RESULTS([$1])
+])
+
+dnl gl_CHECK_FUNCS_MACOS([func], [[#include <foo.h>]])
+dnl is like AC_CHECK_FUNCS([func]), taking into account a portability problem
+dnl on macOS.
+dnl
+dnl When code is compiled on macOS, it is in the context of a certain minimum
+dnl macOS version, that can be set through the option '-mmacosx-version-min='.
+dnl In other words, you don't compile for a specific version of macOS. You
+dnl compile for all versions of macOS, onwards from the given version.
+dnl Thus, the question "does the OS have the function func" has three possible
+dnl answers:
+dnl   - yes, in all versions starting from the given version,
+dnl   - no, in no version,
+dnl   - not in the given version, but in a later version of macOS.
+dnl
+dnl In detail, this works as follows:
+dnl If func was added to, say, macOS version 13, then the libc has the
+dnl symbol func always, whereas the header file <foo.h> declares func
+dnl conditionally with a special availability attribute:
+dnl   ... func (...) __attribute__((availability(macos,introduced=13.0)));
+dnl Thus, when compiling with "clang mmacosx-version-min=13", there is no
+dnl warning about the use of func, and the resulting binary
+dnl   - runs fine on macOS 13,
+dnl   - aborts with a dyld "Symbol not found" message on macOS 12.
+dnl Whereas, when compiling with "clang mmacosx-version-min=12", there is a
+dnl   warning: 'func' is only available on macOS 13.0 or newer
+dnl   [-Wunguarded-availability-new],
+dnl and the resulting binary
+dnl   - runs fine on macOS 13,
+dnl   - crashes with a SIGSEGV (signal 11) on macOS 12.
+dnl
+dnl This macro sets two variables:
+dnl   - gl_cv_onwards_func_<func>   to yes / no / "future OS version"
+dnl   - ac_cv_func_<func>           to yes / no / no
+dnl The first variable allows distinguishing all three cases.
+dnl The second variable is set, so that an invocation
+dnl   gl_CHECK_FUNCS_MACOS([func], [[#include <foo.h>]])
+dnl can be used as a drop-in replacement for
+dnl   AC_CHECK_FUNCS([func]).
+AC_DEFUN([gl_CHECK_FUNCS_MACOS],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_PREPARE_CHECK_FUNCS_MACOS])
+  AC_CACHE_CHECK([for [$1]],
+    [[gl_cv_onwards_func_][$1]],
+    [gl_SILENT([
+       case "$host_os" in
+         gl_CHECK_FUNCS_CASE_FOR_MACOS([$1], [$2])
+         gl_CHECK_FUNCS_DEFAULT_CASE([$1])
+       esac
+      ])
+    ])
+  gl_CHECK_FUNCS_SET_RESULTS([$1])
+])
+
+dnl gl_CHECK_FUNCS_ANDROID_MACOS([func], [[#include <foo.h>]])
+dnl is like AC_CHECK_FUNCS([func]), taking into account a portability problem
+dnl on Android and on macOS.
+dnl It is the combination of gl_CHECK_FUNCS_ANDROID and gl_CHECK_FUNCS_MACOS.
+AC_DEFUN([gl_CHECK_FUNCS_ANDROID_MACOS],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_PREPARE_CHECK_FUNCS_MACOS])
+  AC_CACHE_CHECK([for [$1]],
+    [[gl_cv_onwards_func_][$1]],
+    [gl_SILENT([
+       case "$host_os" in
+         gl_CHECK_FUNCS_CASE_FOR_ANDROID([$1], [$2])
+         gl_CHECK_FUNCS_CASE_FOR_MACOS([$1], [$2])
+         gl_CHECK_FUNCS_DEFAULT_CASE([$1])
+       esac
+      ])
+    ])
+  gl_CHECK_FUNCS_SET_RESULTS([$1])
+])
+
 dnl Expands to some code for use in .c programs that, on native Windows, defines
 dnl the Microsoft deprecated alias function names to the underscore-prefixed
 dnl actual function names. With this macro, these function names are available
diff --git a/gl/m4/gnulib-comp.m4 b/gl/m4/gnulib-comp.m4
index 4764622e..50e98454 100644
--- a/gl/m4/gnulib-comp.m4
+++ b/gl/m4/gnulib-comp.m4
@@ -1,5 +1,5 @@
 # DO NOT EDIT! GENERATED AUTOMATICALLY!
-# Copyright (C) 2002-2023 Free Software Foundation, Inc.
+# Copyright (C) 2002-2025 Free Software Foundation, Inc.
 #
 # This file is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -43,15 +43,32 @@ AC_DEFUN([gl_EARLY],
   AC_REQUIRE([gl_PROG_AR_RANLIB])
 
   # Code from module absolute-header:
+  # Code from module alignasof:
   # Code from module alloca-opt:
-  # Code from module arpa_inet:
+  # Code from module arpa_inet-h:
   # Code from module assert-h:
   # Code from module attribute:
   # Code from module base64:
   # Code from module basename-lgpl:
+  # Code from module bool:
   # Code from module btowc:
   # Code from module builtin-expect:
   # Code from module byteswap:
+  # Code from module c-ctype:
+  # Code from module c32isalnum:
+  # Code from module c32isalpha:
+  # Code from module c32isblank:
+  # Code from module c32iscntrl:
+  # Code from module c32isdigit:
+  # Code from module c32isgraph:
+  # Code from module c32islower:
+  # Code from module c32isprint:
+  # Code from module c32ispunct:
+  # Code from module c32isspace:
+  # Code from module c32isupper:
+  # Code from module c32isxdigit:
+  # Code from module c32tolower:
+  # Code from module c32width:
   # Code from module c99:
   # Code from module calloc-gnu:
   # Code from module calloc-posix:
@@ -65,10 +82,15 @@ AC_DEFUN([gl_EARLY],
   # Code from module double-slash-root:
   # Code from module dup2:
   # Code from module environ:
-  # Code from module errno:
+  # Code from module errno-h:
   # Code from module error:
+  # Code from module error-h:
   # Code from module exitfail:
   # Code from module extensions:
+  # This is actually already done in the pre-early phase.
+  # AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  # Code from module extensions-aix:
+  AC_REQUIRE([gl_USE_AIX_EXTENSIONS])
   # Code from module extern-inline:
   # Code from module fcntl:
   # Code from module fcntl-h:
@@ -76,7 +98,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module fflush:
   AC_REQUIRE([gl_SET_LARGEFILE_SOURCE])
   # Code from module filename:
-  # Code from module float:
+  # Code from module float-h:
   # Code from module floorf:
   # Code from module fopen:
   # Code from module fopen-gnu:
@@ -86,6 +108,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module fseek:
   # Code from module fseeko:
   AC_REQUIRE([gl_SET_LARGEFILE_SOURCE])
+  # Code from module fseterr:
   # Code from module fstat:
   # Code from module fsusage:
   # Code from module ftell:
@@ -103,6 +126,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module getprogname:
   # Code from module gettext-h:
   # Code from module glibc-internal/dynarray:
+  # Code from module gnulib-i18n:
   # Code from module hard-locale:
   # Code from module hostent:
   # Code from module ialloc:
@@ -110,24 +134,36 @@ AC_DEFUN([gl_EARLY],
   # Code from module idx:
   # Code from module include_next:
   # Code from module inet_ntop:
+  # Code from module inet_pton:
   # Code from module intprops:
-  # Code from module inttypes-incomplete:
-  # Code from module langinfo:
+  # Code from module inttypes-h-incomplete:
+  # Code from module iswblank:
+  # Code from module iswctype:
+  # Code from module iswdigit:
+  # Code from module iswpunct:
+  # Code from module iswxdigit:
+  # Code from module langinfo-h:
   # Code from module largefile:
   AC_REQUIRE([AC_SYS_LARGEFILE])
   # Code from module libc-config:
   # Code from module limits-h:
   # Code from module localcharset:
-  # Code from module locale:
+  # Code from module locale-h:
   # Code from module localeconv:
   # Code from module lock:
   # Code from module lseek:
+  # Code from module lstat:
   # Code from module malloc-gnu:
   # Code from module malloc-posix:
   # Code from module malloca:
-  # Code from module math:
+  # Code from module math-h:
+  # Code from module mbchar:
+  # Code from module mbiterf:
+  # Code from module mbrtoc32:
   # Code from module mbrtowc:
   # Code from module mbsinit:
+  # Code from module mbsnlen:
+  # Code from module mbszero:
   # Code from module mbtowc:
   # Code from module memchr:
   # Code from module minmax:
@@ -137,19 +173,24 @@ AC_DEFUN([gl_EARLY],
   # Code from module msvc-inval:
   # Code from module msvc-nothrow:
   # Code from module multiarch:
-  # Code from module netdb:
-  # Code from module netinet_in:
+  # Code from module netdb-h:
+  # Code from module netinet_in-h:
   # Code from module nl_langinfo:
   # Code from module nocrash:
+  # Code from module once:
   # Code from module open:
   # Code from module pathmax:
-  # Code from module realloc-gnu:
+  # Code from module pthread-h:
+  gl_ANYTHREADLIB_EARLY
+  # Code from module pthread-once:
   # Code from module realloc-posix:
   # Code from module reallocarray:
   # Code from module regex:
+  # Code from module sched-h:
   # Code from module servent:
   # Code from module setenv:
   # Code from module setlocale-null:
+  # Code from module setlocale-null-unlocked:
   # Code from module size_max:
   # Code from module snippet/_Noreturn:
   # Code from module snippet/arg-nonnull:
@@ -163,33 +204,56 @@ AC_DEFUN([gl_EARLY],
   # Code from module stat:
   # Code from module stat-time:
   # Code from module std-gnu11:
-  # Code from module stdalign:
-  # Code from module stdbool:
-  # Code from module stdckdint:
-  # Code from module stddef:
-  # Code from module stdint:
-  # Code from module stdio:
-  # Code from module stdlib:
+  # Code from module stdckdint-h:
+  # Code from module stddef-h:
+  # Code from module stdint-h:
+  # Code from module stdio-h:
+  gl_STDIO_H_EARLY
+  # Code from module stdlib-h:
   # Code from module strcase:
+  # Code from module strcasecmp:
   # Code from module strcasestr:
   # Code from module strcasestr-simple:
   # Code from module streq:
   # Code from module strerror:
   # Code from module strerror-override:
-  # Code from module string:
-  # Code from module strings:
+  # Code from module string-h:
+  # Code from module strings-h:
+  # Code from module strncasecmp:
+  # Code from module strncpy:
   # Code from module strsep:
   # Code from module strstr-simple:
-  # Code from module sys_socket:
-  # Code from module sys_stat:
-  # Code from module sys_types:
-  # Code from module sys_uio:
+  # Code from module sys_socket-h:
+  # Code from module sys_stat-h:
+  # Code from module sys_types-h:
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+  # Code from module sys_uio-h:
   # Code from module threadlib:
   gl_THREADLIB_EARLY
-  # Code from module time:
+  # Code from module time-h:
   # Code from module time_r:
   # Code from module timegm:
-  # Code from module unistd:
+  # Code from module uchar-h:
+  # Code from module unicase/base:
+  # Code from module unicase/tolower:
+  # Code from module unictype/base:
+  # Code from module unictype/ctype-alnum:
+  # Code from module unictype/ctype-alpha:
+  # Code from module unictype/ctype-blank:
+  # Code from module unictype/ctype-cntrl:
+  # Code from module unictype/ctype-digit:
+  # Code from module unictype/ctype-graph:
+  # Code from module unictype/ctype-lower:
+  # Code from module unictype/ctype-print:
+  # Code from module unictype/ctype-punct:
+  # Code from module unictype/ctype-space:
+  # Code from module unictype/ctype-upper:
+  # Code from module unictype/ctype-xdigit:
+  # Code from module uninorm/base:
+  # Code from module unistd-h:
+  # Code from module unitypes-h:
+  # Code from module uniwidth/base:
+  # Code from module uniwidth/width:
   # Code from module unlocked-io-internal:
   # Code from module unsetenv:
   # Code from module vararrays:
@@ -197,9 +261,12 @@ AC_DEFUN([gl_EARLY],
   # Code from module vasprintf:
   # Code from module verify:
   # Code from module vsnprintf:
-  # Code from module wchar:
+  # Code from module vsnzprintf:
+  # Code from module wchar-h:
   # Code from module wcrtomb:
+  # Code from module wctype:
   # Code from module wctype-h:
+  # Code from module wcwidth:
   # Code from module windows-mutex:
   # Code from module windows-once:
   # Code from module windows-recmutex:
@@ -229,6 +296,7 @@ AC_DEFUN([gl_INIT],
   gl_COMMON
   gl_source_base='gl'
   gl_source_base_prefix=
+  gl_ALIGNASOF
   gl_FUNC_ALLOCA
   gl_CONDITIONAL_HEADER([alloca.h])
   AC_PROG_MKDIR_P
@@ -239,6 +307,7 @@ AC_DEFUN([gl_INIT],
   gl_CONDITIONAL_HEADER([assert.h])
   AC_PROG_MKDIR_P
   gl_FUNC_BASE64
+  gl_C_BOOL
   gl_FUNC_BTOWC
   gl_CONDITIONAL([GL_COND_OBJ_BTOWC],
                  [test $HAVE_BTOWC = 0 || test $REPLACE_BTOWC = 1])
@@ -250,6 +319,104 @@ AC_DEFUN([gl_INIT],
   gl_BYTESWAP
   gl_CONDITIONAL_HEADER([byteswap.h])
   AC_PROG_MKDIR_P
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isalnum])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isalpha])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isblank])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32iscntrl])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isdigit])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isgraph])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32islower])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isprint])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32ispunct])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isspace])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isupper])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32isxdigit])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32tolower])
+  AC_REQUIRE([gl_UCHAR_H])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how mbrtoc32 is implemented.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  gl_UCHAR_MODULE_INDICATOR([c32width])
   gl_FUNC_CALLOC_GNU
   if test $REPLACE_CALLOC_FOR_CALLOC_GNU = 1; then
     AC_LIBOBJ([calloc])
@@ -264,6 +431,7 @@ AC_DEFUN([gl_INIT],
   gl_FUNC_CLOSE
   gl_CONDITIONAL([GL_COND_OBJ_CLOSE], [test $REPLACE_CLOSE = 1])
   gl_UNISTD_MODULE_INDICATOR([close])
+  gl_MODULE_INDICATOR([close])
   gl_AF_ALG
   AC_REQUIRE([AC_C_RESTRICT])
   gl_SHA256
@@ -280,14 +448,17 @@ AC_DEFUN([gl_INIT],
   gl_HEADER_ERRNO_H
   gl_CONDITIONAL_HEADER([errno.h])
   AC_PROG_MKDIR_P
+  AC_REQUIRE([gl_ERROR_H])
   gl_ERROR
-  gl_CONDITIONAL([GL_COND_OBJ_ERROR], [test "$ac_cv_lib_error_at_line" = no])
+  gl_CONDITIONAL([GL_COND_OBJ_ERROR], [test $COMPILE_ERROR_C = 1])
   AM_COND_IF([GL_COND_OBJ_ERROR], [
     gl_PREREQ_ERROR
   ])
   m4_ifdef([AM_XGETTEXT_OPTION],
     [AM_][XGETTEXT_OPTION([--flag=error:3:c-format])
      AM_][XGETTEXT_OPTION([--flag=error_at_line:5:c-format])])
+  gl_ERROR_H
+  AC_PROG_MKDIR_P
   AC_REQUIRE([gl_EXTERN_INLINE])
   gl_FUNC_FCNTL
   gl_CONDITIONAL([GL_COND_OBJ_FCNTL],
@@ -306,8 +477,11 @@ AC_DEFUN([gl_INIT],
   gl_FLOAT_H
   gl_CONDITIONAL_HEADER([float.h])
   AC_PROG_MKDIR_P
-  gl_CONDITIONAL([GL_COND_OBJ_FLOAT], [test $REPLACE_FLOAT_LDBL = 1])
+  gl_CONDITIONAL([GL_COND_OBJ_FLOAT],
+                 [test $REPLACE_FLOAT_LDBL = 1 || test $REPLACE_FLOAT_SNAN = 1])
   gl_CONDITIONAL([GL_COND_OBJ_ITOLD], [test $REPLACE_ITOLD = 1])
+  dnl Prerequisites of lib/float.c.
+  AC_REQUIRE([gl_BIGENDIAN])
   gl_FUNC_FLOORF
   gl_CONDITIONAL([GL_COND_OBJ_FLOORF],
                  [test $HAVE_DECL_FLOORF = 0 || test $REPLACE_FLOORF = 1])
@@ -346,17 +520,20 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_FSEEKO
   ])
   gl_STDIO_MODULE_INDICATOR([fseeko])
+  gl_FUNC_FSETERR
+  gl_CONDITIONAL([GL_COND_OBJ_FSETERR], [test $ac_cv_func___fseterr = no])
   gl_FUNC_FSTAT
   gl_CONDITIONAL([GL_COND_OBJ_FSTAT], [test $REPLACE_FSTAT = 1])
   AM_COND_IF([GL_COND_OBJ_FSTAT], [
     case "$host_os" in
-      mingw*)
+      mingw* | windows*)
         AC_LIBOBJ([stat-w32])
         ;;
     esac
     gl_PREREQ_FSTAT
   ])
   gl_SYS_STAT_MODULE_INDICATOR([fstat])
+  gl_MODULE_INDICATOR([fstat])
   gl_FSUSAGE
   gl_CONDITIONAL([GL_COND_OBJ_FSUSAGE], [test $gl_cv_fs_space = yes])
   AM_COND_IF([GL_COND_OBJ_FSUSAGE], [
@@ -398,6 +575,7 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_GETHOSTNAME
   ])
   gl_UNISTD_MODULE_INDICATOR([gethostname])
+  gl_MODULE_INDICATOR([gethostname])
   gl_FUNC_GETLINE
   gl_CONDITIONAL([GL_COND_OBJ_GETLINE], [test $REPLACE_GETLINE = 1])
   AM_COND_IF([GL_COND_OBJ_GETLINE], [
@@ -406,7 +584,8 @@ AC_DEFUN([gl_INIT],
   gl_STDIO_MODULE_INDICATOR([getline])
   AC_REQUIRE([AC_CANONICAL_HOST])
   gl_GETLOADAVG
-  gl_CONDITIONAL([GL_COND_OBJ_GETLOADAVG], [test $HAVE_GETLOADAVG = 0])
+  gl_CONDITIONAL([GL_COND_OBJ_GETLOADAVG],
+                 [test $HAVE_GETLOADAVG = 0 || test $REPLACE_GETLOADAVG = 1])
   AM_COND_IF([GL_COND_OBJ_GETLOADAVG], [
     gl_PREREQ_GETLOADAVG
   ])
@@ -426,12 +605,24 @@ AC_DEFUN([gl_INIT],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNISTD_H_GETOPT], [1])
   ])
   gl_UNISTD_MODULE_INDICATOR([getopt-posix])
+  gl_MUSL_LIBC
+  AC_REQUIRE([AC_CANONICAL_HOST])
   gl_FUNC_GETPROGNAME
+  gl_CONDITIONAL([GL_COND_OBJ_GETPROGNAME],
+                 [test $HAVE_GETPROGNAME = 0 || test $REPLACE_GETPROGNAME = 1])
+  AM_COND_IF([GL_COND_OBJ_GETPROGNAME], [
+    gl_PREREQ_GETPROGNAME
+  ])
+  gl_STDLIB_MODULE_INDICATOR([getprogname])
   AC_SUBST([LIBINTL])
   AC_SUBST([LTLIBINTL])
   AC_PROG_MKDIR_P
+  GNULIB_I18N
   AC_REQUIRE([gl_FUNC_SETLOCALE_NULL])
-  LIB_HARD_LOCALE="$LIB_SETLOCALE_NULL"
+  HARD_LOCALE_LIB="$SETLOCALE_NULL_LIB"
+  AC_SUBST([HARD_LOCALE_LIB])
+  dnl For backward compatibility.
+  LIB_HARD_LOCALE="$HARD_LOCALE_LIB"
   AC_SUBST([LIB_HARD_LOCALE])
   gl_HOSTENT
   gl_IDPRIV
@@ -442,9 +633,36 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_INET_NTOP
   ])
   gl_ARPA_INET_MODULE_INDICATOR([inet_ntop])
+  gl_FUNC_INET_PTON
+  gl_CONDITIONAL([GL_COND_OBJ_INET_PTON],
+                 [test $HAVE_INET_PTON = 0 || test $REPLACE_INET_PTON = 1])
+  AM_COND_IF([GL_COND_OBJ_INET_PTON], [
+    gl_PREREQ_INET_PTON
+  ])
+  gl_ARPA_INET_MODULE_INDICATOR([inet_pton])
   gl_INTTYPES_INCOMPLETE
   gl_INTTYPES_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
+  gl_FUNC_ISWBLANK
+  gl_CONDITIONAL([GL_COND_OBJ_ISWBLANK],
+                 [! { test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; } && { test $HAVE_ISWBLANK = 0 || test $REPLACE_ISWBLANK = 1; }])
+  gl_WCTYPE_MODULE_INDICATOR([iswblank])
+  gl_FUNC_ISWCTYPE
+  gl_CONDITIONAL([GL_COND_OBJ_ISWCTYPE],
+                 [test $HAVE_WCTYPE_T = 0 || test $GNULIBHEADERS_OVERRIDE_WINT_T = 1 || test $REPLACE_WCTYPE = 1])
+  gl_WCTYPE_MODULE_INDICATOR([iswctype])
+  gl_FUNC_ISWDIGIT
+  gl_CONDITIONAL([GL_COND_OBJ_ISWDIGIT],
+                 [! { test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; } && test $REPLACE_ISWDIGIT = 1])
+  gl_WCTYPE_MODULE_INDICATOR([iswdigit])
+  gl_FUNC_ISWPUNCT
+  gl_CONDITIONAL([GL_COND_OBJ_ISWPUNCT],
+                 [! { test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; } && test $REPLACE_ISWPUNCT = 1])
+  gl_WCTYPE_MODULE_INDICATOR([iswpunct])
+  gl_FUNC_ISWXDIGIT
+  gl_CONDITIONAL([GL_COND_OBJ_ISWXDIGIT],
+                 [! { test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; } && test $REPLACE_ISWXDIGIT = 1])
+  gl_WCTYPE_MODULE_INDICATOR([iswxdigit])
   gl_LANGINFO_H
   gl_LANGINFO_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
@@ -466,11 +684,19 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_LOCALECONV
   ])
   gl_LOCALE_MODULE_INDICATOR([localeconv])
+  gl_MODULE_INDICATOR([localeconv])
   gl_LOCK
   gl_MODULE_INDICATOR([lock])
   gl_FUNC_LSEEK
   gl_CONDITIONAL([GL_COND_OBJ_LSEEK], [test $REPLACE_LSEEK = 1])
   gl_UNISTD_MODULE_INDICATOR([lseek])
+  gl_FUNC_LSTAT
+  gl_CONDITIONAL([GL_COND_OBJ_LSTAT], [test $REPLACE_LSTAT = 1])
+  AM_COND_IF([GL_COND_OBJ_LSTAT], [
+    gl_PREREQ_LSTAT
+  ])
+  gl_SYS_STAT_MODULE_INDICATOR([lstat])
+  gl_MODULE_INDICATOR([lstat])
   gl_FUNC_MALLOC_GNU
   if test $REPLACE_MALLOC_FOR_MALLOC_GNU = 1; then
     AC_LIBOBJ([malloc])
@@ -485,6 +711,20 @@ AC_DEFUN([gl_INIT],
   gl_MATH_H
   gl_MATH_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
+  gl_MBCHAR
+  gl_MBITER
+  gl_FUNC_MBRTOC32
+  gl_CONDITIONAL([GL_COND_OBJ_MBRTOC32],
+                 [test $HAVE_MBRTOC32 = 0 || test $REPLACE_MBRTOC32 = 1])
+  AM_COND_IF([GL_COND_OBJ_MBRTOC32], [
+    if test $REPLACE_MBSTATE_T = 1; then
+      AC_LIBOBJ([lc-charset-dispatch])
+      AC_LIBOBJ([mbtowc-lock])
+      gl_PREREQ_MBTOWC_LOCK
+    fi
+    gl_PREREQ_MBRTOC32
+  ])
+  gl_UCHAR_MODULE_INDICATOR([mbrtoc32])
   gl_FUNC_MBRTOWC
   gl_CONDITIONAL([GL_COND_OBJ_MBRTOWC],
                  [test $HAVE_MBRTOWC = 0 || test $REPLACE_MBRTOWC = 1])
@@ -504,6 +744,11 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_MBSINIT
   ])
   gl_WCHAR_MODULE_INDICATOR([mbsinit])
+  gl_STRING_MODULE_INDICATOR([mbsnlen])
+  AC_REQUIRE([AC_TYPE_MBSTATE_T])
+  gl_MBSTATE_T_BROKEN
+  gl_MUSL_LIBC
+  gl_WCHAR_MODULE_INDICATOR([mbszero])
   gl_FUNC_MBTOWC
   gl_CONDITIONAL([GL_COND_OBJ_MBTOWC],
                  [test $HAVE_MBTOWC = 0 || test $REPLACE_MBTOWC = 1])
@@ -530,10 +775,7 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_MKTIME
   fi
   gl_MOUNTLIST
-  gl_CONDITIONAL([GL_COND_OBJ_MOUNTLIST], [test $gl_cv_list_mounted_fs = yes])
-  AM_COND_IF([GL_COND_OBJ_MOUNTLIST], [
-    gl_PREREQ_MOUNTLIST_EXTRA
-  ])
+  gl_PREREQ_MOUNTLIST_EXTRA
   AC_REQUIRE([gl_MSVC_INVAL])
   gl_CONDITIONAL([GL_COND_OBJ_MSVC_INVAL],
                  [test $HAVE_MSVC_INVALID_PARAMETER_HANDLER = 1])
@@ -557,6 +799,7 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_NL_LANGINFO_LOCK
   fi
   gl_LANGINFO_MODULE_INDICATOR([nl_langinfo])
+  gl_ONCE
   gl_FUNC_OPEN
   gl_CONDITIONAL([GL_COND_OBJ_OPEN], [test $REPLACE_OPEN = 1])
   AM_COND_IF([GL_COND_OBJ_OPEN], [
@@ -564,15 +807,17 @@ AC_DEFUN([gl_INIT],
   ])
   gl_FCNTL_MODULE_INDICATOR([open])
   gl_PATHMAX
-  gl_FUNC_REALLOC_GNU
-  if test $REPLACE_REALLOC_FOR_REALLOC_GNU = 1; then
-    AC_LIBOBJ([realloc])
-  fi
-  gl_STDLIB_MODULE_INDICATOR([realloc-gnu])
+  gl_PTHREAD_H
+  gl_PTHREAD_H_REQUIRE_DEFAULTS
+  AC_PROG_MKDIR_P
+  gl_PTHREAD_ONCE
+  gl_CONDITIONAL([GL_COND_OBJ_PTHREAD_ONCE],
+                 [test $HAVE_PTHREAD_ONCE = 0 || test $REPLACE_PTHREAD_ONCE = 1])
+  gl_PTHREAD_MODULE_INDICATOR([pthread-once])
   gl_FUNC_REALLOC_POSIX
-  if test $REPLACE_REALLOC_FOR_REALLOC_POSIX = 1; then
-    AC_LIBOBJ([realloc])
-  fi
+  gl_FUNC_REALLOC_0_NONNULL
+  gl_CONDITIONAL([GL_COND_OBJ_REALLOC_POSIX],
+                 [test $REPLACE_REALLOC_FOR_REALLOC_POSIX != 0])
   gl_STDLIB_MODULE_INDICATOR([realloc-posix])
   gl_FUNC_REALLOCARRAY
   gl_CONDITIONAL([GL_COND_OBJ_REALLOCARRAY],
@@ -587,6 +832,9 @@ AC_DEFUN([gl_INIT],
   AM_COND_IF([GL_COND_OBJ_REGEX], [
     gl_PREREQ_REGEX
   ])
+  gl_SCHED_H
+  gl_SCHED_H_REQUIRE_DEFAULTS
+  AC_PROG_MKDIR_P
   gl_SERVENT
   gl_FUNC_SETENV
   gl_CONDITIONAL([GL_COND_OBJ_SETENV],
@@ -611,25 +859,17 @@ AC_DEFUN([gl_INIT],
   gl_CONDITIONAL([GL_COND_OBJ_STAT], [test $REPLACE_STAT = 1])
   AM_COND_IF([GL_COND_OBJ_STAT], [
     case "$host_os" in
-      mingw*)
+      mingw* | windows*)
         AC_LIBOBJ([stat-w32])
         ;;
     esac
     gl_PREREQ_STAT
   ])
   gl_SYS_STAT_MODULE_INDICATOR([stat])
+  gl_MODULE_INDICATOR([stat])
   gl_STAT_TIME
   gl_STAT_BIRTHTIME
-  gl_STDALIGN_H
-  gl_CONDITIONAL_HEADER([stdalign.h])
-  AC_PROG_MKDIR_P
-  gl_C_BOOL
-  AC_CHECK_HEADERS_ONCE([stdckdint.h])
-  if test $ac_cv_header_stdckdint_h = yes; then
-    GL_GENERATE_STDCKDINT_H=false
-  else
-    GL_GENERATE_STDCKDINT_H=true
-  fi
+  gl_STDCKDINT_H
   gl_CONDITIONAL_HEADER([stdckdint.h])
   AC_PROG_MKDIR_P
   gl_STDDEF_H
@@ -644,6 +884,19 @@ AC_DEFUN([gl_INIT],
   gl_STDIO_H
   gl_STDIO_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
+  USES_MSVCRT=0
+  case "$host_os" in
+    mingw* | windows*)
+      AC_EGREP_CPP([Special], [
+  #ifndef _UCRT
+   Special
+  #endif
+        ],
+        [USES_MSVCRT=1])
+      ;;
+  esac
+  gl_CONDITIONAL([GL_COND_OBJ_STDIO_CONSOLESAFE], [test $USES_MSVCRT = 1])
+  AC_CHECK_FUNCS([vasprintf])
   gl_CONDITIONAL([GL_COND_OBJ_STDIO_READ], [test $REPLACE_STDIO_READ_FUNCS = 1])
   gl_CONDITIONAL([GL_COND_OBJ_STDIO_WRITE], [test $REPLACE_STDIO_WRITE_FUNCS = 1])
   dnl No need to create extra modules for these functions. Everyone who uses
@@ -672,15 +925,13 @@ AC_DEFUN([gl_INIT],
   gl_STDLIB_H
   gl_STDLIB_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
-  gl_STRCASE
-  gl_CONDITIONAL([GL_COND_OBJ_STRCASECMP], [test $HAVE_STRCASECMP = 0])
+  gl_FUNC_STRCASECMP
+  gl_CONDITIONAL([GL_COND_OBJ_STRCASECMP],
+                 [test $HAVE_STRCASECMP = 0 || test $REPLACE_STRCASECMP = 1])
   AM_COND_IF([GL_COND_OBJ_STRCASECMP], [
     gl_PREREQ_STRCASECMP
   ])
-  gl_CONDITIONAL([GL_COND_OBJ_STRNCASECMP], [test $HAVE_STRNCASECMP = 0])
-  AM_COND_IF([GL_COND_OBJ_STRNCASECMP], [
-    gl_PREREQ_STRNCASECMP
-  ])
+  gl_STRINGS_MODULE_INDICATOR([strcasecmp])
   gl_FUNC_STRCASESTR
   if test $HAVE_STRCASESTR = 0 || test $REPLACE_STRCASESTR = 1; then
     AC_LIBOBJ([strcasestr])
@@ -709,6 +960,19 @@ AC_DEFUN([gl_INIT],
   gl_STRINGS_H
   gl_STRINGS_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
+  gl_FUNC_STRNCASECMP
+  gl_CONDITIONAL([GL_COND_OBJ_STRNCASECMP],
+                 [test $HAVE_STRNCASECMP = 0 || test $REPLACE_STRNCASECMP = 1])
+  AM_COND_IF([GL_COND_OBJ_STRNCASECMP], [
+    gl_PREREQ_STRNCASECMP
+  ])
+  gl_STRINGS_MODULE_INDICATOR([strncasecmp])
+  gl_FUNC_STRNCPY
+  gl_CONDITIONAL([GL_COND_OBJ_STRNCPY], [test $REPLACE_STRNCPY = 1])
+  AM_COND_IF([GL_COND_OBJ_STRNCPY], [
+    gl_PREREQ_STRNCPY
+  ])
+  gl_STRING_MODULE_INDICATOR([strncpy])
   gl_FUNC_STRSEP
   gl_CONDITIONAL([GL_COND_OBJ_STRSEP], [test $HAVE_STRSEP = 0])
   AM_COND_IF([GL_COND_OBJ_STRSEP], [
@@ -750,9 +1014,55 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_TIMEGM
   ])
   gl_TIME_MODULE_INDICATOR([timegm])
+  gl_UCHAR_H
+  gl_UCHAR_H_REQUIRE_DEFAULTS
+  AC_PROG_MKDIR_P
+  gl_LIBUNISTRING_LIBHEADER([1.2], [unicase.h])
+  gl_UNICASE_H
+  gl_UNICASE_H_REQUIRE_DEFAULTS
+  AC_PROG_MKDIR_P
+  gl_LIBUNISTRING_MODULE([1.3], [unicase/tolower])
+  gl_LIBUNISTRING_LIBHEADER([1.3], [unictype.h])
+  gl_UNICTYPE_H
+  gl_UNICTYPE_H_REQUIRE_DEFAULTS
+  AC_PROG_MKDIR_P
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([1.3], [unictype/ctype-alnum])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([1.3], [unictype/ctype-alpha])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([0.9.8], [unictype/ctype-blank])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([0.9.8], [unictype/ctype-cntrl])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([0.9.8], [unictype/ctype-digit])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([1.3], [unictype/ctype-graph])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([1.3], [unictype/ctype-lower])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([1.3], [unictype/ctype-print])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([1.3], [unictype/ctype-punct])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([0.9.8], [unictype/ctype-space])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([1.3], [unictype/ctype-upper])
+  AC_REQUIRE([AC_C_INLINE])
+  gl_LIBUNISTRING_MODULE([0.9.8], [unictype/ctype-xdigit])
+  gl_LIBUNISTRING_LIBHEADER([1.2], [uninorm.h])
+  gl_UNINORM_H
+  gl_UNINORM_H_REQUIRE_DEFAULTS
+  AC_PROG_MKDIR_P
   gl_UNISTD_H
   gl_UNISTD_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
+  gl_LIBUNISTRING_LIBHEADER([0.9.11], [unitypes.h])
+  AC_PROG_MKDIR_P
+  gl_UNITYPES_H
+  gl_LIBUNISTRING_LIBHEADER([0.9.11], [uniwidth.h])
+  AC_PROG_MKDIR_P
+  gl_LIBUNISTRING_MODULE([1.3], [uniwidth/width])
   gl_FUNC_GLIBC_UNLOCKED_IO
   gl_FUNC_UNSETENV
   gl_CONDITIONAL([GL_COND_OBJ_UNSETENV],
@@ -771,6 +1081,7 @@ AC_DEFUN([gl_INIT],
      AM_][XGETTEXT_OPTION([--flag=vasprintf:2:c-format])])
   gl_FUNC_VSNPRINTF
   gl_STDIO_MODULE_INDICATOR([vsnprintf])
+  gl_STDIO_MODULE_INDICATOR([vsnzprintf])
   gl_WCHAR_H
   gl_WCHAR_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
@@ -781,21 +1092,31 @@ AC_DEFUN([gl_INIT],
     gl_PREREQ_WCRTOMB
   ])
   gl_WCHAR_MODULE_INDICATOR([wcrtomb])
+  gl_FUNC_WCTYPE
+  gl_CONDITIONAL([GL_COND_OBJ_WCTYPE], [test $HAVE_WCTYPE = 0 || test $REPLACE_WCTYPE = 1])
+  gl_WCTYPE_MODULE_INDICATOR([wctype])
   gl_WCTYPE_H
   gl_WCTYPE_H_REQUIRE_DEFAULTS
   AC_PROG_MKDIR_P
+  gl_FUNC_WCWIDTH
+  gl_CONDITIONAL([GL_COND_OBJ_WCWIDTH],
+                 [test $HAVE_WCWIDTH = 0 || test $REPLACE_WCWIDTH = 1])
+  AM_COND_IF([GL_COND_OBJ_WCWIDTH], [
+    gl_PREREQ_WCWIDTH
+  ])
+  gl_WCHAR_MODULE_INDICATOR([wcwidth])
   AC_REQUIRE([AC_CANONICAL_HOST])
   gl_CONDITIONAL([GL_COND_OBJ_WINDOWS_MUTEX],
-                 [case "$host_os" in mingw*) true;; *) false;; esac])
+                 [case "$host_os" in mingw* | windows*) true;; *) false;; esac])
   AC_REQUIRE([AC_CANONICAL_HOST])
   gl_CONDITIONAL([GL_COND_OBJ_WINDOWS_ONCE],
-                 [case "$host_os" in mingw*) true;; *) false;; esac])
+                 [case "$host_os" in mingw* | windows*) true;; *) false;; esac])
   AC_REQUIRE([AC_CANONICAL_HOST])
   gl_CONDITIONAL([GL_COND_OBJ_WINDOWS_RECMUTEX],
-                 [case "$host_os" in mingw*) true;; *) false;; esac])
+                 [case "$host_os" in mingw* | windows*) true;; *) false;; esac])
   AC_REQUIRE([AC_CANONICAL_HOST])
   gl_CONDITIONAL([GL_COND_OBJ_WINDOWS_RWLOCK],
-                 [case "$host_os" in mingw*) true;; *) false;; esac])
+                 [case "$host_os" in mingw* | windows*) true;; *) false;; esac])
   gl_XALLOC
   gl_MODULE_INDICATOR([xalloc])
   gl_MODULE_INDICATOR([xalloc-die])
@@ -823,27 +1144,35 @@ AC_DEFUN([gl_INIT],
     gl_libobjs=
     gl_ltlibobjs=
     gl_libobjdeps=
+    gl_libgnu_libobjs=
+    gl_libgnu_ltlibobjs=
+    gl_libgnu_libobjdeps=
     if test -n "$gl_LIBOBJS"; then
       # Remove the extension.
 changequote(,)dnl
       sed_drop_objext='s/\.o$//;s/\.obj$//'
       sed_dirname1='s,//*,/,g'
       sed_dirname2='s,\(.\)/$,\1,'
-      sed_dirname3='s,^[^/]*$,.,'
-      sed_dirname4='s,\(.\)/[^/]*$,\1,'
+      sed_dirname3='s,[^/]*$,,'
       sed_basename1='s,.*/,,'
 changequote([, ])dnl
       for i in `for i in $gl_LIBOBJS; do echo "$i"; done | sed -e "$sed_drop_objext" | sort | uniq`; do
         gl_libobjs="$gl_libobjs $i.$ac_objext"
         gl_ltlibobjs="$gl_ltlibobjs $i.lo"
-        i_dir=`echo "$i" | sed -e "$sed_dirname1" -e "$sed_dirname2" -e "$sed_dirname3" -e "$sed_dirname4"`
+        i_dir=`echo "$i" | sed -e "$sed_dirname1" -e "$sed_dirname2" -e "$sed_dirname3"`
         i_base=`echo "$i" | sed -e "$sed_basename1"`
-        gl_libobjdeps="$gl_libobjdeps $i_dir/\$(DEPDIR)/$i_base.Po"
+        gl_libgnu_libobjs="$gl_libgnu_libobjs $i_dir""libgnu_a-$i_base.$ac_objext"
+        gl_libgnu_ltlibobjs="$gl_libgnu_ltlibobjs $i_dir""libgnu_la-$i_base.lo"
+        gl_libobjdeps="$gl_libobjdeps $i_dir\$(DEPDIR)/$i_base.Po"
+        gl_libgnu_libobjdeps="$gl_libgnu_libobjdeps $i_dir\$(DEPDIR)/libgnu_a-$i_base.Po"
       done
     fi
     AC_SUBST([gl_LIBOBJS], [$gl_libobjs])
     AC_SUBST([gl_LTLIBOBJS], [$gl_ltlibobjs])
     AC_SUBST([gl_LIBOBJDEPS], [$gl_libobjdeps])
+    AC_SUBST([gl_libgnu_LIBOBJS], [$gl_libgnu_libobjs])
+    AC_SUBST([gl_libgnu_LTLIBOBJS], [$gl_libgnu_ltlibobjs])
+    AC_SUBST([gl_libgnu_LIBOBJDEPS], [$gl_libgnu_libobjdeps])
   ])
   gltests_libdeps=
   gltests_ltlibdeps=
@@ -886,27 +1215,35 @@ changequote([, ])dnl
     gltests_libobjs=
     gltests_ltlibobjs=
     gltests_libobjdeps=
+    gltests_libgnu_libobjs=
+    gltests_libgnu_ltlibobjs=
+    gltests_libgnu_libobjdeps=
     if test -n "$gltests_LIBOBJS"; then
       # Remove the extension.
 changequote(,)dnl
       sed_drop_objext='s/\.o$//;s/\.obj$//'
       sed_dirname1='s,//*,/,g'
       sed_dirname2='s,\(.\)/$,\1,'
-      sed_dirname3='s,^[^/]*$,.,'
-      sed_dirname4='s,\(.\)/[^/]*$,\1,'
+      sed_dirname3='s,[^/]*$,,'
       sed_basename1='s,.*/,,'
 changequote([, ])dnl
       for i in `for i in $gltests_LIBOBJS; do echo "$i"; done | sed -e "$sed_drop_objext" | sort | uniq`; do
         gltests_libobjs="$gltests_libobjs $i.$ac_objext"
         gltests_ltlibobjs="$gltests_ltlibobjs $i.lo"
-        i_dir=`echo "$i" | sed -e "$sed_dirname1" -e "$sed_dirname2" -e "$sed_dirname3" -e "$sed_dirname4"`
+        i_dir=`echo "$i" | sed -e "$sed_dirname1" -e "$sed_dirname2" -e "$sed_dirname3"`
         i_base=`echo "$i" | sed -e "$sed_basename1"`
-        gltests_libobjdeps="$gltests_libobjdeps $i_dir/\$(DEPDIR)/$i_base.Po"
+        gltests_libgnu_libobjs="$gltests_libgnu_libobjs $i_dir""libgnu_a-$i_base.$ac_objext"
+        gltests_libgnu_ltlibobjs="$gltests_libgnu_ltlibobjs $i_dir""libgnu_la-$i_base.lo"
+        gltests_libobjdeps="$gltests_libobjdeps $i_dir\$(DEPDIR)/$i_base.Po"
+        gltests_libgnu_libobjdeps="$gltests_libgnu_libobjdeps $i_dir\$(DEPDIR)/libgnu_a-$i_base.Po"
       done
     fi
     AC_SUBST([gltests_LIBOBJS], [$gltests_libobjs])
     AC_SUBST([gltests_LTLIBOBJS], [$gltests_ltlibobjs])
     AC_SUBST([gltests_LIBOBJDEPS], [$gltests_libobjdeps])
+    AC_SUBST([gltests_libgnu_LIBOBJS], [$gltests_libgnu_libobjs])
+    AC_SUBST([gltests_libgnu_LTLIBOBJS], [$gltests_libgnu_ltlibobjs])
+    AC_SUBST([gltests_libgnu_LIBOBJDEPS], [$gltests_libgnu_libobjdeps])
   ])
   AC_REQUIRE([gl_CC_GNULIB_WARNINGS])
   LIBGNU_LIBDEPS="$gl_libdeps"
@@ -977,6 +1314,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/af_alg.h
   lib/alloca.in.h
   lib/arg-nonnull.h
+  lib/arpa_inet.c
   lib/arpa_inet.in.h
   lib/asnprintf.c
   lib/asprintf.c
@@ -988,8 +1326,27 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/basename-lgpl.h
   lib/basename.c
   lib/btowc.c
+  lib/byteswap.c
   lib/byteswap.in.h
   lib/c++defs.h
+  lib/c-ctype.c
+  lib/c-ctype.h
+  lib/c32is-impl.h
+  lib/c32isalnum.c
+  lib/c32isalpha.c
+  lib/c32isblank.c
+  lib/c32iscntrl.c
+  lib/c32isdigit.c
+  lib/c32isgraph.c
+  lib/c32islower.c
+  lib/c32isprint.c
+  lib/c32ispunct.c
+  lib/c32isspace.c
+  lib/c32isupper.c
+  lib/c32isxdigit.c
+  lib/c32to-impl.h
+  lib/c32tolower.c
+  lib/c32width.c
   lib/calloc.c
   lib/cdefs.h
   lib/cloexec.c
@@ -1002,7 +1359,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/dynarray.h
   lib/errno.in.h
   lib/error.c
-  lib/error.h
+  lib/error.in.h
   lib/exitfail.c
   lib/exitfail.h
   lib/fcntl.c
@@ -1023,6 +1380,8 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/free.c
   lib/fseek.c
   lib/fseeko.c
+  lib/fseterr.c
+  lib/fseterr.h
   lib/fstat.c
   lib/fsusage.c
   lib/fsusage.h
@@ -1050,6 +1409,8 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/gl_openssl.h
   lib/glthread/lock.c
   lib/glthread/lock.h
+  lib/glthread/once.c
+  lib/glthread/once.h
   lib/glthread/threadlib.c
   lib/hard-locale.c
   lib/hard-locale.h
@@ -1059,9 +1420,16 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/idpriv.h
   lib/idx.h
   lib/inet_ntop.c
+  lib/inet_pton.c
   lib/intprops-internal.h
   lib/intprops.h
   lib/inttypes.in.h
+  lib/iswblank.c
+  lib/iswctype-impl.h
+  lib/iswctype.c
+  lib/iswdigit.c
+  lib/iswpunct.c
+  lib/iswxdigit.c
   lib/itold.c
   lib/langinfo.in.h
   lib/lc-charset-dispatch.c
@@ -1073,6 +1441,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/locale.in.h
   lib/localeconv.c
   lib/lseek.c
+  lib/lstat.c
   lib/malloc.c
   lib/malloc/dynarray-skeleton.c
   lib/malloc/dynarray.h
@@ -1085,10 +1454,17 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/malloca.h
   lib/math.c
   lib/math.in.h
+  lib/mbchar.c
+  lib/mbchar.h
+  lib/mbiterf.c
+  lib/mbiterf.h
+  lib/mbrtoc32.c
   lib/mbrtowc-impl-utf8.h
   lib/mbrtowc-impl.h
   lib/mbrtowc.c
   lib/mbsinit.c
+  lib/mbsnlen.c
+  lib/mbszero.c
   lib/mbtowc-impl.h
   lib/mbtowc-lock.c
   lib/mbtowc-lock.h
@@ -1114,6 +1490,8 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/printf-args.h
   lib/printf-parse.c
   lib/printf-parse.h
+  lib/pthread-once.c
+  lib/pthread.in.h
   lib/realloc.c
   lib/reallocarray.c
   lib/regcomp.c
@@ -1122,8 +1500,10 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/regex_internal.c
   lib/regex_internal.h
   lib/regexec.c
+  lib/sched.in.h
   lib/setenv.c
   lib/setlocale-lock.c
+  lib/setlocale_null-unlocked.c
   lib/setlocale_null.c
   lib/setlocale_null.h
   lib/sha256-stream.c
@@ -1138,14 +1518,15 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/stat-w32.c
   lib/stat-w32.h
   lib/stat.c
-  lib/stdalign.in.h
   lib/stdckdint.in.h
   lib/stddef.in.h
   lib/stdint.in.h
+  lib/stdio-consolesafe.c
   lib/stdio-impl.h
   lib/stdio-read.c
   lib/stdio-write.c
   lib/stdio.in.h
+  lib/stdlib.c
   lib/stdlib.in.h
   lib/str-two-way.h
   lib/strcasecmp.c
@@ -1158,6 +1539,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/strings.in.h
   lib/stripslash.c
   lib/strncasecmp.c
+  lib/strncpy.c
   lib/strsep.c
   lib/strstr.c
   lib/sys-limits.h
@@ -1169,8 +1551,46 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/time.in.h
   lib/time_r.c
   lib/timegm.c
+  lib/uchar.in.h
+  lib/unicase.in.h
+  lib/unicase/simple-mapping.h
+  lib/unicase/tolower.c
+  lib/unicase/tolower.h
+  lib/unictype.in.h
+  lib/unictype/bitmap.h
+  lib/unictype/ctype_alnum.c
+  lib/unictype/ctype_alnum.h
+  lib/unictype/ctype_alpha.c
+  lib/unictype/ctype_alpha.h
+  lib/unictype/ctype_blank.c
+  lib/unictype/ctype_blank.h
+  lib/unictype/ctype_cntrl.c
+  lib/unictype/ctype_cntrl.h
+  lib/unictype/ctype_digit.c
+  lib/unictype/ctype_digit.h
+  lib/unictype/ctype_graph.c
+  lib/unictype/ctype_graph.h
+  lib/unictype/ctype_lower.c
+  lib/unictype/ctype_lower.h
+  lib/unictype/ctype_print.c
+  lib/unictype/ctype_print.h
+  lib/unictype/ctype_punct.c
+  lib/unictype/ctype_punct.h
+  lib/unictype/ctype_space.c
+  lib/unictype/ctype_space.h
+  lib/unictype/ctype_upper.c
+  lib/unictype/ctype_upper.h
+  lib/unictype/ctype_xdigit.c
+  lib/unictype/ctype_xdigit.h
+  lib/uninorm.in.h
   lib/unistd.c
   lib/unistd.in.h
+  lib/unitypes.in.h
+  lib/uniwidth.in.h
+  lib/uniwidth/cjk.h
+  lib/uniwidth/width.c
+  lib/uniwidth/width0.h
+  lib/uniwidth/width2.h
   lib/unlocked-io.h
   lib/unsetenv.c
   lib/vasnprintf.c
@@ -1178,12 +1598,16 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/vasprintf.c
   lib/verify.h
   lib/vsnprintf.c
+  lib/vsnzprintf.c
   lib/w32sock.h
   lib/warn-on-use.h
   lib/wchar.in.h
   lib/wcrtomb.c
   lib/wctype-h.c
+  lib/wctype-impl.h
+  lib/wctype.c
   lib/wctype.in.h
+  lib/wcwidth.c
   lib/windows-initguard.h
   lib/windows-mutex.c
   lib/windows-mutex.h
@@ -1208,21 +1632,25 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/assert_h.m4
   m4/base64.m4
   m4/btowc.m4
+  m4/build-to-host.m4
   m4/builtin-expect.m4
   m4/byteswap.m4
   m4/c-bool.m4
+  m4/c32rtomb.m4
   m4/calloc.m4
   m4/close.m4
   m4/codeset.m4
   m4/double-slash-root.m4
   m4/dup2.m4
-  m4/eealloc.m4
   m4/environ.m4
   m4/errno_h.m4
   m4/error.m4
+  m4/error_h.m4
   m4/exponentd.m4
+  m4/extensions-aix.m4
   m4/extensions.m4
   m4/extern-inline.m4
+  m4/fclose.m4
   m4/fcntl-o.m4
   m4/fcntl.m4
   m4/fcntl_h.m4
@@ -1235,6 +1663,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/free.m4
   m4/fseek.m4
   m4/fseeko.m4
+  m4/fseterr.m4
   m4/fstat.m4
   m4/fstypename.m4
   m4/fsusage.m4
@@ -1250,17 +1679,26 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/getprogname.m4
   m4/gl-openssl.m4
   m4/gnulib-common.m4
+  m4/gnulib-i18n.m4
   m4/hostent.m4
   m4/idpriv.m4
   m4/include_next.m4
   m4/inet_ntop.m4
+  m4/inet_pton.m4
   m4/intmax_t.m4
   m4/inttypes.m4
   m4/inttypes_h.m4
+  m4/iswblank.m4
+  m4/iswctype.m4
+  m4/iswdigit.m4
+  m4/iswpunct.m4
+  m4/iswxdigit.m4
   m4/langinfo_h.m4
   m4/largefile.m4
+  m4/libunistring-base.m4
   m4/limits-h.m4
   m4/localcharset.m4
+  m4/locale-en.m4
   m4/locale-fr.m4
   m4/locale-ja.m4
   m4/locale-zh.m4
@@ -1268,9 +1706,13 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/localeconv.m4
   m4/lock.m4
   m4/lseek.m4
+  m4/lstat.m4
   m4/malloc.m4
   m4/malloca.m4
   m4/math_h.m4
+  m4/mbchar.m4
+  m4/mbiter.m4
+  m4/mbrtoc32.m4
   m4/mbrtowc.m4
   m4/mbsinit.m4
   m4/mbstate_t.m4
@@ -1284,21 +1726,28 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/msvc-inval.m4
   m4/msvc-nothrow.m4
   m4/multiarch.m4
+  m4/musl.m4
   m4/netdb_h.m4
   m4/netinet_in_h.m4
   m4/nl_langinfo.m4
   m4/nocrash.m4
+  m4/off64_t.m4
   m4/off_t.m4
+  m4/once.m4
   m4/open-cloexec.m4
   m4/open-slash.m4
   m4/open.m4
   m4/pathmax.m4
   m4/pid_t.m4
   m4/printf.m4
+  m4/pthread-once.m4
+  m4/pthread-spin.m4
+  m4/pthread_h.m4
   m4/pthread_rwlock_rdlock.m4
   m4/realloc.m4
   m4/reallocarray.m4
   m4/regex.m4
+  m4/sched_h.m4
   m4/servent.m4
   m4/setenv.m4
   m4/setlocale_null.m4
@@ -1314,18 +1763,22 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/stat.m4
   m4/std-gnu11.m4
   m4/stdalign.m4
+  m4/stdckdint_h.m4
   m4/stddef_h.m4
   m4/stdint.m4
   m4/stdint_h.m4
   m4/stdio_h.m4
   m4/stdlib_h.m4
-  m4/strcase.m4
+  m4/strcasecmp.m4
   m4/strcasestr.m4
   m4/strerror.m4
   m4/string_h.m4
   m4/strings_h.m4
+  m4/strncasecmp.m4
+  m4/strncpy.m4
   m4/strsep.m4
   m4/strstr.m4
+  m4/sys_cdefs_h.m4
   m4/sys_socket_h.m4
   m4/sys_stat_h.m4
   m4/sys_types_h.m4
@@ -1334,8 +1787,13 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/time_h.m4
   m4/time_r.m4
   m4/timegm.m4
+  m4/uchar_h.m4
   m4/ungetc.m4
+  m4/unicase_h.m4
+  m4/unictype_h.m4
+  m4/uninorm_h.m4
   m4/unistd_h.m4
+  m4/unitypes_h.m4
   m4/unlocked-io.m4
   m4/vararrays.m4
   m4/vasnprintf.m4
@@ -1344,9 +1802,10 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/vsnprintf.m4
   m4/warn-on-use.m4
   m4/wchar_h.m4
-  m4/wchar_t.m4
   m4/wcrtomb.m4
+  m4/wctype.m4
   m4/wctype_h.m4
+  m4/wcwidth.m4
   m4/wint_t.m4
   m4/xalloc.m4
   m4/xsize.m4
diff --git a/gl/m4/gnulib-i18n.m4 b/gl/m4/gnulib-i18n.m4
new file mode 100644
index 00000000..868043e7
--- /dev/null
+++ b/gl/m4/gnulib-i18n.m4
@@ -0,0 +1,61 @@
+# gnulib-i18n.m4
+# serial 1
+dnl Copyright (C) 2005-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl From Bruno Haible.
+
+dnl Support for internationalization of Gnulib code.
+
+dnl GNULIB_I18N
+dnl Sets GNULIB_LOCALEDIR to indicate where to find the gnulib.mo files.
+dnl Also it defines GNULIB_LOCALEDIR as macro in config.h, that expands to
+dnl the corresponding C string.
+AC_DEFUN([GNULIB_I18N],
+[
+  dnl It is best to not test "$USE_NLS" here, because: It would be empty
+  dnl in case the package is internationalized but this macro is used before
+  dnl AM_GNU_GETTEXT. We would need to warn about this situation. But since
+  dnl this module is used as a dependency of many packages, such a warning is
+  dnl not welcome.
+
+  dnl Determine gnulib's localedir.
+  dnl Generally, accept an option --with-gnulib-prefix=PREFIX to indicate
+  dnl where to find gnulib's runtime data.
+  dnl Usually ${prefix}/share/locale, but can be influenced by the configure
+  dnl options --datarootdir and --localedir.
+  GNULIB_LOCALEDIR="${localedir}"
+  AC_ARG_WITH([gnulib-prefix],
+    [[  --with-gnulib-prefix=DIR  search for gnulib's runtime data in DIR/share]],
+    [if test "X$withval" != "X" && test "X$withval" != "Xno"; then
+       GNULIB_LOCALEDIR="$withval/share/locale"
+     fi
+    ])
+  AC_SUBST([GNULIB_LOCALEDIR])
+
+  dnl Define GNULIB_LOCALEDIR_c and GNULIB_LOCALEDIR_c_make.
+  dnl Find the final value of GNULIB_LOCALEDIR.
+  gl_saved_prefix="${prefix}"
+  gl_saved_datarootdir="${datarootdir}"
+  gl_saved_localedir="${localedir}"
+  gl_saved_gnuliblocaledir="${GNULIB_LOCALEDIR}"
+  dnl Unfortunately, prefix gets only finally determined at the end of
+  dnl configure.
+  if test "X$prefix" = "XNONE"; then
+    prefix="$ac_default_prefix"
+  fi
+  eval datarootdir="$datarootdir"
+  eval localedir="$localedir"
+  eval GNULIB_LOCALEDIR="$GNULIB_LOCALEDIR"
+  gl_BUILD_TO_HOST([GNULIB_LOCALEDIR])
+  GNULIB_LOCALEDIR="${gl_saved_gnuliblocaledir}"
+  localedir="${gl_saved_localedir}"
+  datarootdir="${gl_saved_datarootdir}"
+  prefix="${gl_saved_prefix}"
+
+  AC_DEFINE_UNQUOTED([GNULIB_LOCALEDIR], [${GNULIB_LOCALEDIR_c}],
+    [Define to the directory where to find the localizations of the translation domain 'gnulib', as a C string.])
+])
diff --git a/gl/m4/gnulib-tool.m4 b/gl/m4/gnulib-tool.m4
index a9dd569b..8634a6e9 100644
--- a/gl/m4/gnulib-tool.m4
+++ b/gl/m4/gnulib-tool.m4
@@ -1,8 +1,10 @@
-# gnulib-tool.m4 serial 4
-dnl Copyright (C) 2004-2005, 2009-2023 Free Software Foundation, Inc.
+# gnulib-tool.m4
+# serial 5
+dnl Copyright (C) 2004-2005, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl The following macros need not be invoked explicitly.
 dnl Invoking them does nothing except to declare default arguments
@@ -41,6 +43,9 @@ AC_DEFUN([gl_LIB], [])
 dnl Usage: gl_LGPL or gl_LGPL([VERSION])
 AC_DEFUN([gl_LGPL], [])
 
+dnl Usage: gl_GPL([VERSION])
+AC_DEFUN([gl_GPL], [])
+
 dnl Usage: gl_MAKEFILE_NAME([FILENAME])
 AC_DEFUN([gl_MAKEFILE_NAME], [])
 
diff --git a/gl/m4/hostent.m4 b/gl/m4/hostent.m4
index 3b2cc2b2..9278285c 100644
--- a/gl/m4/hostent.m4
+++ b/gl/m4/hostent.m4
@@ -1,8 +1,10 @@
-# hostent.m4 serial 4
-dnl Copyright (C) 2008, 2010-2023 Free Software Foundation, Inc.
+# hostent.m4
+# serial 5
+dnl Copyright (C) 2008, 2010-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_HOSTENT],
 [
@@ -26,7 +28,7 @@ AC_DEFUN([gl_HOSTENT],
       AC_CACHE_CHECK([for gethostbyname in winsock2.h and -lws2_32],
         [gl_cv_w32_gethostbyname],
         [gl_cv_w32_gethostbyname=no
-         gl_save_LIBS="$LIBS"
+         gl_saved_LIBS="$LIBS"
          LIBS="$LIBS -lws2_32"
          AC_LINK_IFELSE(
            [AC_LANG_PROGRAM(
@@ -38,7 +40,7 @@ AC_DEFUN([gl_HOSTENT],
               ]],
               [[gethostbyname(NULL);]])],
            [gl_cv_w32_gethostbyname=yes])
-         LIBS="$gl_save_LIBS"
+         LIBS="$gl_saved_LIBS"
         ])
       if test "$gl_cv_w32_gethostbyname" = "yes"; then
         HOSTENT_LIB="-lws2_32"
diff --git a/gl/m4/idpriv.m4 b/gl/m4/idpriv.m4
index fc3dd17d..6e855e9a 100644
--- a/gl/m4/idpriv.m4
+++ b/gl/m4/idpriv.m4
@@ -1,8 +1,10 @@
-# idpriv.m4 serial 1
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# idpriv.m4
+# serial 1
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_IDPRIV],
 [
diff --git a/gl/m4/include_next.m4 b/gl/m4/include_next.m4
index 9f19215e..80de991e 100644
--- a/gl/m4/include_next.m4
+++ b/gl/m4/include_next.m4
@@ -1,8 +1,10 @@
-# include_next.m4 serial 26
-dnl Copyright (C) 2006-2023 Free Software Foundation, Inc.
+# include_next.m4
+# serial 27
+dnl Copyright (C) 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Paul Eggert and Derek Price.
 
@@ -74,17 +76,17 @@ EOF
 #endif
 #define DEFINED_IN_CONFTESTD2
 EOF
-     gl_save_CPPFLAGS="$CPPFLAGS"
-     CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2"
+     gl_saved_CPPFLAGS="$CPPFLAGS"
+     CPPFLAGS="$gl_saved_CPPFLAGS -Iconftestd1b -Iconftestd2"
 dnl We intentionally avoid using AC_LANG_SOURCE here.
      AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[#include <conftest.h>]],
        [gl_cv_have_include_next=yes],
-       [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2"
+       [CPPFLAGS="$gl_saved_CPPFLAGS -Iconftestd1a -Iconftestd2"
         AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[#include <conftest.h>]],
           [gl_cv_have_include_next=buggy],
           [gl_cv_have_include_next=no])
        ])
-     CPPFLAGS="$gl_save_CPPFLAGS"
+     CPPFLAGS="$gl_saved_CPPFLAGS"
      rm -rf conftestd1a conftestd1b conftestd2
     ])
   PRAGMA_SYSTEM_HEADER=
diff --git a/gl/m4/inet_ntop.m4 b/gl/m4/inet_ntop.m4
index 48822d69..693bd51b 100644
--- a/gl/m4/inet_ntop.m4
+++ b/gl/m4/inet_ntop.m4
@@ -1,8 +1,10 @@
-# inet_ntop.m4 serial 21
-dnl Copyright (C) 2005-2006, 2008-2023 Free Software Foundation, Inc.
+# inet_ntop.m4
+# serial 22
+dnl Copyright (C) 2005-2006, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_INET_NTOP],
 [
@@ -36,14 +38,14 @@ AC_DEFUN([gl_FUNC_INET_NTOP],
       HAVE_DECL_INET_NTOP=0
     fi
   else
-    gl_save_LIBS=$LIBS
+    gl_saved_LIBS=$LIBS
     AC_SEARCH_LIBS([inet_ntop], [nsl resolv network], [],
       [AC_CHECK_FUNCS([inet_ntop])
        if test $ac_cv_func_inet_ntop = no; then
          HAVE_INET_NTOP=0
        fi
       ])
-    LIBS=$gl_save_LIBS
+    LIBS=$gl_saved_LIBS
 
     if test "$ac_cv_search_inet_ntop" != "no" \
        && test "$ac_cv_search_inet_ntop" != "none required"; then
diff --git a/gl/m4/inet_pton.m4 b/gl/m4/inet_pton.m4
new file mode 100644
index 00000000..b6e59a25
--- /dev/null
+++ b/gl/m4/inet_pton.m4
@@ -0,0 +1,72 @@
+# inet_pton.m4
+# serial 20
+dnl Copyright (C) 2006, 2008-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_INET_PTON],
+[
+  AC_REQUIRE([gl_ARPA_INET_H_DEFAULTS])
+
+  dnl Persuade Solaris <arpa/inet.h> to declare inet_pton.
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  dnl Most platforms that provide inet_pton define it in libc.
+  dnl Solaris 8..10 provide inet_pton in libnsl instead.
+  dnl Solaris 2.6..7 provide inet_pton in libresolv instead.
+  dnl Haiku provides it in -lnetwork.
+  dnl Native Windows provides it in -lws2_32 instead, with a declaration in
+  dnl <ws2tcpip.h>, and it uses stdcall calling convention, not cdecl
+  dnl (hence we cannot use AC_CHECK_FUNCS, AC_SEARCH_LIBS to find it).
+  HAVE_INET_PTON=1
+  INET_PTON_LIB=
+  gl_PREREQ_SYS_H_WINSOCK2
+  if test $HAVE_WINSOCK2_H = 1; then
+    dnl It needs to be overridden, because the stdcall calling convention
+    dnl is not compliant with POSIX.  Set REPLACE_INET_PTON in order to avoid
+    dnl a name conflict at the linker level, even though the header file
+    dnl <ws2tcpip.h> declares inet_pton only if _WIN32_WINNT >= 0x0600.
+    REPLACE_INET_PTON=1
+    AC_CHECK_DECLS([inet_pton],,, [[#include <ws2tcpip.h>]])
+    if test $ac_cv_have_decl_inet_pton = yes; then
+      INET_PTON_LIB="-lws2_32"
+    else
+      HAVE_DECL_INET_PTON=0
+    fi
+  else
+    gl_saved_LIBS=$LIBS
+    AC_SEARCH_LIBS([inet_pton], [nsl resolv network], [],
+      [AC_CHECK_FUNCS([inet_pton])
+       if test $ac_cv_func_inet_pton = no; then
+         HAVE_INET_PTON=0
+       fi
+      ])
+    LIBS=$gl_saved_LIBS
+
+    if test "$ac_cv_search_inet_pton" != "no" \
+       && test "$ac_cv_search_inet_pton" != "none required"; then
+      INET_PTON_LIB="$ac_cv_search_inet_pton"
+    fi
+
+    AC_CHECK_HEADERS_ONCE([netdb.h])
+    AC_CHECK_DECLS([inet_pton],,,
+      [[#include <arpa/inet.h>
+        #if HAVE_NETDB_H
+        # include <netdb.h>
+        #endif
+      ]])
+    if test $ac_cv_have_decl_inet_pton = no; then
+      HAVE_DECL_INET_PTON=0
+    fi
+  fi
+  AC_SUBST([INET_PTON_LIB])
+])
+
+# Prerequisites of lib/inet_pton.c.
+AC_DEFUN([gl_PREREQ_INET_PTON], [
+  AC_REQUIRE([gl_SOCKET_FAMILIES])
+])
diff --git a/gl/m4/intmax_t.m4 b/gl/m4/intmax_t.m4
index ef32e1b9..c1df7b27 100644
--- a/gl/m4/intmax_t.m4
+++ b/gl/m4/intmax_t.m4
@@ -1,9 +1,11 @@
-# intmax_t.m4 serial 9
-dnl Copyright (C) 1997-2004, 2006-2007, 2009-2023 Free Software Foundation,
+# intmax_t.m4
+# serial 9
+dnl Copyright (C) 1997-2004, 2006-2007, 2009-2025 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Paul Eggert.
 
diff --git a/gl/m4/inttypes.m4 b/gl/m4/inttypes.m4
index bf2eab2b..63c82c61 100644
--- a/gl/m4/inttypes.m4
+++ b/gl/m4/inttypes.m4
@@ -1,8 +1,10 @@
-# inttypes.m4 serial 36
-dnl Copyright (C) 2006-2023 Free Software Foundation, Inc.
+# inttypes.m4
+# serial 37
+dnl Copyright (C) 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Derek Price, Bruno Haible.
 dnl Test whether <inttypes.h> is supported or must be substituted.
@@ -170,6 +172,10 @@ AC_DEFUN([gl_INTTYPES_H_DEFAULTS],
   HAVE_DECL_STRTOIMAX=1; AC_SUBST([HAVE_DECL_STRTOIMAX])
   HAVE_DECL_STRTOUMAX=1; AC_SUBST([HAVE_DECL_STRTOUMAX])
   HAVE_IMAXDIV_T=1;      AC_SUBST([HAVE_IMAXDIV_T])
+  HAVE_IMAXABS=1;        AC_SUBST([HAVE_IMAXABS])
+  HAVE_IMAXDIV=1;        AC_SUBST([HAVE_IMAXDIV])
+  REPLACE_IMAXABS=0;     AC_SUBST([REPLACE_IMAXABS])
+  REPLACE_IMAXDIV=0;     AC_SUBST([REPLACE_IMAXDIV])
   REPLACE_STRTOIMAX=0;   AC_SUBST([REPLACE_STRTOIMAX])
   REPLACE_STRTOUMAX=0;   AC_SUBST([REPLACE_STRTOUMAX])
   INT32_MAX_LT_INTMAX_MAX=1;  AC_SUBST([INT32_MAX_LT_INTMAX_MAX])
diff --git a/gl/m4/inttypes_h.m4 b/gl/m4/inttypes_h.m4
index 68c60e9d..ad939a53 100644
--- a/gl/m4/inttypes_h.m4
+++ b/gl/m4/inttypes_h.m4
@@ -1,8 +1,10 @@
-# inttypes_h.m4 serial 10
-dnl Copyright (C) 1997-2004, 2006, 2008-2023 Free Software Foundation, Inc.
+# inttypes_h.m4
+# serial 10
+dnl Copyright (C) 1997-2004, 2006, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Paul Eggert.
 
diff --git a/gl/m4/iswblank.m4 b/gl/m4/iswblank.m4
new file mode 100644
index 00000000..d06b16a2
--- /dev/null
+++ b/gl/m4/iswblank.m4
@@ -0,0 +1,40 @@
+# iswblank.m4
+# serial 7
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_ISWBLANK],
+[
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H])
+  dnl Persuade glibc <wctype.h> to declare iswblank().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  gl_CHECK_FUNCS_ANDROID([iswblank], [[#include <wctype.h>]])
+  AC_CHECK_DECLS([iswblank], , , [[
+    #include <wchar.h>
+    #include <wctype.h>
+  ]])
+  if test $ac_cv_func_iswblank = no; then
+    HAVE_ISWBLANK=0
+    if test $ac_cv_have_decl_iswblank = yes \
+       || case "$gl_cv_onwards_func_iswblank" in \
+            future*) true ;; \
+            *) false ;; \
+          esac; then
+      REPLACE_ISWBLANK=1
+    fi
+  fi
+  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
+    dnl Redefine all of iswcntrl, ..., towupper in <wctype.h>.
+    :
+  else
+    if test $HAVE_ISWBLANK = 0 || test $REPLACE_ISWBLANK = 1; then
+      dnl Redefine only iswblank.
+      :
+    fi
+  fi
+
+])
diff --git a/gl/m4/iswctype.m4 b/gl/m4/iswctype.m4
new file mode 100644
index 00000000..f5a3b760
--- /dev/null
+++ b/gl/m4/iswctype.m4
@@ -0,0 +1,15 @@
+# iswctype.m4
+# serial 3
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_ISWCTYPE],
+[
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H])
+  dnl Determine REPLACE_WCTYPE.
+  AC_REQUIRE([gl_FUNC_WCTYPE])
+])
diff --git a/gl/m4/iswdigit.m4 b/gl/m4/iswdigit.m4
new file mode 100644
index 00000000..4582f598
--- /dev/null
+++ b/gl/m4/iswdigit.m4
@@ -0,0 +1,122 @@
+# iswdigit.m4
+# serial 9
+dnl Copyright (C) 2020-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_ISWDIGIT],
+[
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H])
+  AC_REQUIRE([gt_LOCALE_FR])
+  AC_REQUIRE([gt_LOCALE_JA])
+  AC_REQUIRE([gt_LOCALE_EN_UTF8])
+  AC_REQUIRE([gt_LOCALE_ZH_CN])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
+    dnl <wctype.h> redefines iswdigit already.
+    REPLACE_ISWDIGIT="$REPLACE_ISWCNTRL"
+  else
+    AC_CACHE_CHECK([whether iswdigit is ISO C compliant],
+      [gl_cv_func_iswdigit_works],
+      [
+       dnl Initial guess, used when cross-compiling or when no suitable locale
+       dnl is present.
+changequote(,)dnl
+       case "$host_os" in
+         # Guess no on FreeBSD, NetBSD, OpenBSD, Solaris, native Windows, Haiku, Android.
+         freebsd* | dragonfly* | netbsd* | openbsd* | solaris* | mingw* | windows* | haiku* | *-android*)
+           gl_cv_func_iswdigit_works="guessing no" ;;
+         # Guess yes otherwise.
+         *) gl_cv_func_iswdigit_works="guessing yes" ;;
+       esac
+changequote([,])dnl
+       if test $LOCALE_FR != none || test $LOCALE_JA != none || test "$LOCALE_EN_UTF8" != none || test $LOCALE_ZH_CN != none; then
+         AC_RUN_IFELSE(
+           [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <wctype.h>
+
+/* Returns the value of iswdigit for the multibyte character s[0..n-1].  */
+static int
+for_character (const char *s, size_t n)
+{
+  mbstate_t state;
+  wchar_t wc;
+  size_t ret;
+
+  memset (&state, '\0', sizeof (mbstate_t));
+  wc = (wchar_t) 0xBADFACE;
+  ret = mbrtowc (&wc, s, n, &state);
+  if (ret != n)
+    abort ();
+
+  return iswdigit (wc);
+}
+
+int
+main (int argc, char *argv[])
+{
+  int is;
+  int result = 0;
+
+  if (strcmp ("$LOCALE_FR", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_FR") != NULL)
+    {
+      /* This fails on mingw, MSVC 14.  */
+      /* U+00B2 SUPERSCRIPT TWO */
+      is = for_character ("\262", 1);
+      if (!(is == 0))
+        result |= 1;
+    }
+  if (strcmp ("$LOCALE_JA", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_JA") != NULL)
+    {
+      /* This fails on NetBSD 10.0.  */
+      /* U+FF11 FULLWIDTH DIGIT ONE */
+      is = for_character ("\243\261", 2);
+      if (!(is == 0))
+        result |= 2;
+    }
+  if (strcmp ("$LOCALE_EN_UTF8", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
+    {
+      /* This fails on FreeBSD 13.0, NetBSD 10.0, OpenBSD 7.5, MSVC 14, Haiku, Android.  */
+      /* U+0663 ARABIC-INDIC DIGIT THREE */
+      is = for_character ("\331\243", 2);
+      if (!(is == 0))
+        result |= 4;
+      /* This fails on FreeBSD 13.0, NetBSD 10.0, OpenBSD 7.5, MSVC 14, Haiku, Android.  */
+      /* U+FF11 FULLWIDTH DIGIT ONE */
+      is = for_character ("\357\274\221", 3);
+      if (!(is == 0))
+        result |= 8;
+    }
+  if (strcmp ("$LOCALE_ZH_CN", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_ZH_CN") != NULL)
+    {
+      /* This fails on NetBSD 10.0, Solaris 10, Solaris 11.4.  */
+      /* U+FF11 FULLWIDTH DIGIT ONE */
+      is = for_character ("\243\261", 2);
+      if (!(is == 0))
+        result |= 16;
+    }
+  return result;
+}]])],
+           [gl_cv_func_iswdigit_works=yes],
+           [gl_cv_func_iswdigit_works=no],
+           [:])
+       fi
+      ])
+    case "$gl_cv_func_iswdigit_works" in
+      *yes) ;;
+      *) REPLACE_ISWDIGIT=1 ;;
+    esac
+  fi
+])
diff --git a/gl/m4/iswpunct.m4 b/gl/m4/iswpunct.m4
new file mode 100644
index 00000000..d8e8d712
--- /dev/null
+++ b/gl/m4/iswpunct.m4
@@ -0,0 +1,50 @@
+# iswpunct.m4
+# serial 2
+dnl Copyright (C) 2023-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_ISWPUNCT],
+[
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
+    dnl <wctype.h> redefines iswpunct already.
+    REPLACE_ISWPUNCT="$REPLACE_ISWCNTRL"
+  else
+    AC_CACHE_CHECK([whether iswpunct is consistent with ispunct],
+      [gl_cv_func_iswpunct_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE([[
+#include <ctype.h>
+#include <wchar.h>
+#include <wctype.h>
+int
+main (int argc, char *argv[])
+{
+  int result = 0;
+  /* This fails on Android 11.  */
+  if ((! iswpunct ('\`')) != (! ispunct ('\`')))
+    result |= 1;
+  return result;
+}]])],
+         [gl_cv_func_iswpunct_works=yes],
+         [gl_cv_func_iswpunct_works=no],
+         [case "$host_os" in
+            # Guess no on Android.
+            android*) gl_cv_func_iswpunct_works="guessing no" ;;
+            # Guess yes otherwise.
+            *)        gl_cv_func_iswpunct_works="guessing yes" ;;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_iswpunct_works" in
+      *yes) ;;
+      *) REPLACE_ISWPUNCT=1 ;;
+    esac
+  fi
+])
diff --git a/gl/m4/iswxdigit.m4 b/gl/m4/iswxdigit.m4
new file mode 100644
index 00000000..95226fc4
--- /dev/null
+++ b/gl/m4/iswxdigit.m4
@@ -0,0 +1,112 @@
+# iswxdigit.m4
+# serial 9
+dnl Copyright (C) 2020-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_ISWXDIGIT],
+[
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H])
+  AC_REQUIRE([gt_LOCALE_JA])
+  AC_REQUIRE([gt_LOCALE_EN_UTF8])
+  AC_REQUIRE([gt_LOCALE_ZH_CN])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
+    dnl <wctype.h> redefines iswxdigit already.
+    REPLACE_ISWXDIGIT="$REPLACE_ISWCNTRL"
+  else
+    AC_CACHE_CHECK([whether iswxdigit is ISO C compliant],
+      [gl_cv_func_iswxdigit_works],
+      [
+       dnl Initial guess, used when cross-compiling or when no suitable locale
+       dnl is present.
+changequote(,)dnl
+       case "$host_os" in
+         # Guess no on FreeBSD, NetBSD, OpenBSD, Solaris, native Windows, Haiku, Android.
+         freebsd* | dragonfly* | netbsd* | openbsd* | solaris* | mingw* | windows* | haiku* | *-android*)
+           gl_cv_func_iswxdigit_works="guessing no" ;;
+         # Guess yes otherwise.
+         *) gl_cv_func_iswxdigit_works="guessing yes" ;;
+       esac
+changequote([,])dnl
+       if test $LOCALE_JA != none || test "$LOCALE_EN_UTF8" != none || test $LOCALE_ZH_CN != none; then
+         AC_RUN_IFELSE(
+           [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <wctype.h>
+
+/* Returns the value of iswxdigit for the multibyte character s[0..n-1].  */
+static int
+for_character (const char *s, size_t n)
+{
+  mbstate_t state;
+  wchar_t wc;
+  size_t ret;
+
+  memset (&state, '\0', sizeof (mbstate_t));
+  wc = (wchar_t) 0xBADFACE;
+  ret = mbrtowc (&wc, s, n, &state);
+  if (ret != n)
+    abort ();
+
+  return iswxdigit (wc);
+}
+
+int
+main (int argc, char *argv[])
+{
+  int is;
+  int result = 0;
+
+  if (strcmp ("$LOCALE_JA", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_JA") != NULL)
+    {
+      /* This fails on NetBSD 10.0.  */
+      /* U+FF21 FULLWIDTH LATIN CAPITAL LETTER A */
+      is = for_character ("\243\301", 2);
+      if (!(is == 0))
+        result |= 1;
+    }
+  if (strcmp ("$LOCALE_EN_UTF8", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
+    {
+      /* This fails on FreeBSD 13.0, Haiku, Android.  */
+      /* U+0663 ARABIC-INDIC DIGIT THREE */
+      is = for_character ("\331\243", 2);
+      if (!(is == 0))
+        result |= 2;
+      /* This fails on NetBSD 10.0, OpenBSD 7.5, MSVC 14, Haiku, Android.  */
+      /* U+FF21 FULLWIDTH LATIN CAPITAL LETTER A */
+      is = for_character ("\357\274\241", 3);
+      if (!(is == 0))
+        result |= 4;
+    }
+  if (strcmp ("$LOCALE_ZH_CN", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_ZH_CN") != NULL)
+    {
+      /* This fails on Solaris 10, Solaris 11.4.  */
+      /* U+FF11 FULLWIDTH DIGIT ONE */
+      is = for_character ("\243\261", 2);
+      if (!(is == 0))
+        result |= 8;
+    }
+  return result;
+}]])],
+           [gl_cv_func_iswxdigit_works=yes],
+           [gl_cv_func_iswxdigit_works=no],
+           [:])
+       fi
+      ])
+    case "$gl_cv_func_iswxdigit_works" in
+      *yes) ;;
+      *) REPLACE_ISWXDIGIT=1 ;;
+    esac
+  fi
+])
diff --git a/gl/m4/langinfo_h.m4 b/gl/m4/langinfo_h.m4
index b17a526a..69f936f0 100644
--- a/gl/m4/langinfo_h.m4
+++ b/gl/m4/langinfo_h.m4
@@ -1,8 +1,10 @@
-# langinfo_h.m4 serial 12
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# langinfo_h.m4
+# serial 13
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_LANGINFO_H],
 [
@@ -18,6 +20,7 @@ AC_DEFUN_ONCE([gl_LANGINFO_H],
   HAVE_LANGINFO_CODESET=0
   HAVE_LANGINFO_T_FMT_AMPM=0
   HAVE_LANGINFO_ALTMON=0
+  HAVE_LANGINFO_ABALTMON=0
   HAVE_LANGINFO_ERA=0
   HAVE_LANGINFO_YESEXPR=0
   AC_CHECK_HEADERS_ONCE([langinfo.h])
@@ -28,6 +31,7 @@ AC_DEFUN_ONCE([gl_LANGINFO_H],
     dnl ERA etc. are missing on OpenBSD 6.7.
     dnl T_FMT_AMPM and YESEXPR, NOEXPR are missing on IRIX 5.3.
     dnl ALTMON_* are missing on glibc 2.26 and many other systems.
+    dnl ABALTMON_* are missing on glibc 2.41 and many other systems.
     AC_CACHE_CHECK([whether langinfo.h defines CODESET],
       [gl_cv_header_langinfo_codeset],
       [AC_COMPILE_IFELSE(
@@ -64,6 +68,18 @@ int a = ALTMON_1;
     if test $gl_cv_header_langinfo_altmon = yes; then
       HAVE_LANGINFO_ALTMON=1
     fi
+    AC_CACHE_CHECK([whether langinfo.h defines ABALTMON_1],
+      [gl_cv_header_langinfo_abaltmon],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM([[#include <langinfo.h>
+int a = ABALTMON_1;
+]])],
+         [gl_cv_header_langinfo_abaltmon=yes],
+         [gl_cv_header_langinfo_abaltmon=no])
+      ])
+    if test $gl_cv_header_langinfo_abaltmon = yes; then
+      HAVE_LANGINFO_ABALTMON=1
+    fi
     AC_CACHE_CHECK([whether langinfo.h defines ERA],
       [gl_cv_header_langinfo_era],
       [AC_COMPILE_IFELSE(
@@ -95,6 +111,7 @@ int a = YESEXPR;
   AC_SUBST([HAVE_LANGINFO_CODESET])
   AC_SUBST([HAVE_LANGINFO_T_FMT_AMPM])
   AC_SUBST([HAVE_LANGINFO_ALTMON])
+  AC_SUBST([HAVE_LANGINFO_ABALTMON])
   AC_SUBST([HAVE_LANGINFO_ERA])
   AC_SUBST([HAVE_LANGINFO_YESEXPR])
 
diff --git a/gl/m4/largefile.m4 b/gl/m4/largefile.m4
index 7fb81b86..b24f657d 100644
--- a/gl/m4/largefile.m4
+++ b/gl/m4/largefile.m4
@@ -1,16 +1,19 @@
+# largefile.m4
+# serial 2
+dnl Copyright 1992-1996, 1998-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
 # Enable large files on systems where this is not the default.
 # Enable support for files on Linux file systems with 64-bit inode numbers.
 
-# Copyright 1992-1996, 1998-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
-
 # The following macro works around a problem in Autoconf's AC_FUNC_FSEEKO:
 # It does not set _LARGEFILE_SOURCE=1 on HP-UX/ia64 32-bit, although this
 # setting of _LARGEFILE_SOURCE is needed so that <stdio.h> declares fseeko
 # and ftello in C++ mode as well.
-# Fixed in Autoconf 2.72, which has AC_SYS_YEAR2038.
+# This problem occurs in Autoconf 2.71 and earlier, which lack AC_SYS_YEAR2038.
 AC_DEFUN([gl_SET_LARGEFILE_SOURCE],
  m4_ifndef([AC_SYS_YEAR2038], [[
   AC_REQUIRE([AC_CANONICAL_HOST])
@@ -24,29 +27,20 @@ AC_DEFUN([gl_SET_LARGEFILE_SOURCE],
  ]])
 )
 
-# Work around a problem in autoconf <= 2.69:
-# AC_SYS_LARGEFILE does not configure for large inodes on Mac OS X 10.5,
-# or configures them incorrectly in some cases.
-m4_version_prereq([2.70], [], [
-
-# _AC_SYS_LARGEFILE_TEST_INCLUDES
-# -------------------------------
-m4_define([_AC_SYS_LARGEFILE_TEST_INCLUDES],
-[#include <sys/types.h>
- /* Check that off_t can represent 2**63 - 1 correctly.
-    We can't simply define LARGE_OFF_T to be 9223372036854775807,
-    since some C++ compilers masquerading as C compilers
-    incorrectly reject 9223372036854775807.  */
-#define LARGE_OFF_T (((off_t) 1 << 31 << 31) - 1 + ((off_t) 1 << 31 << 31))
-  int off_t_is_large[[(LARGE_OFF_T % 2147483629 == 721
-                       && LARGE_OFF_T % 2147483647 == 1)
-                      ? 1 : -1]];[]dnl
-])
-])# m4_version_prereq 2.70
+dnl Remove AC_SYS_YEAR2038_RECOMMENDED if unpatched Autoconf 2.72 or earlier.
+dnl Autoconf 2.72 still uses -n32, which is not a C preprocessor option,
+dnl and which was useful only on IRIX which is no longer supported.
+dnl This should be fixed in Autoconf 2.73.
+m4_ifdef([AC_SYS_YEAR2038_RECOMMENDED],
+  [m4_bmatch(m4_ifdef([_AC_SYS_LARGEFILE_OPTIONS],
+               [m4_defn([_AC_SYS_LARGEFILE_OPTIONS])],
+               ["-n32"]),
+     ["-n32"],
+       [m4_undefine([AC_SYS_YEAR2038_RECOMMENDED])])])
 
-# Support AC_SYS_YEAR2038, even if Autoconf 2.71 or earlier.
-# This code is taken from Autoconf master.
-m4_ifndef([AC_SYS_YEAR2038], [
+m4_ifndef([AC_SYS_YEAR2038_RECOMMENDED], [
+# Fix up AC_SYS_YEAR2038_RECOMMENDED and related macros, even if
+# unpatched Autoconf 2.72 or earlier.  This code is taken from Autoconf master.
 
 # _AC_SYS_YEAR2038_TEST_CODE
 # --------------------------
@@ -78,8 +72,8 @@ m4_define([_AC_SYS_YEAR2038_OPTIONS], m4_normalize(
                                       dnl 32-bit MinGW (misconfiguration)
 ))
 
-# _AC_SYS_YEAR2038_PROBE([IF-NOT-DETECTED])
-# -----------------------------------------
+# _AC_SYS_YEAR2038_PROBE
+# ----------------------
 # Subroutine of AC_SYS_YEAR2038.  Probe for time_t that can represent
 # time points more than 2**31 - 1 seconds after the epoch (dates after
 # 2038-01-18, see above) and set the cache variable ac_cv_sys_year2038_opts
@@ -92,13 +86,10 @@ m4_define([_AC_SYS_YEAR2038_OPTIONS], m4_normalize(
 # AC_TRY_RUN.  Note also that some systems only support large time_t
 # together with large off_t.
 #
-# If support is not detected, the behavior depends on which of the
-# top-level AC_SYS_YEAR2038 macros was used (see below).
-#
 # If you change this macro you may also need to change
 # _AC_SYS_YEAR2038_OPTIONS.
 AC_DEFUN([_AC_SYS_YEAR2038_PROBE],
-[AC_CACHE_CHECK([for $CC option to enable timestamps after Jan 2038],
+[AC_CACHE_CHECK([for $CC option to support timestamps after 2038],
   [ac_cv_sys_year2038_opts],
   [ac_save_CPPFLAGS="$CPPFLAGS"
   ac_opt_found=no
@@ -117,40 +108,20 @@ ac_have_year2038=yes
 AS_CASE([$ac_cv_sys_year2038_opts],
   ["none needed"], [],
   ["support not detected"],
-    [ac_have_year2038=no
-     AS_CASE([$enable_year2038],
-      [yes],
-        [# If we're not cross compiling and 'touch' works with a large
-        # timestamp, then we can presume the system supports wider time_t
-        # *somehow* and we just weren't able to detect it.  One common
-        # case that we deliberately *don't* probe for is a system that
-        # supports both 32- and 64-bit ABIs but only the 64-bit ABI offers
-        # wide time_t.  (It would be inappropriate for us to override an
-        # intentional use of -m32.)  Error out, demanding use of
-        # --disable-year2038 if this is intentional.
-        AS_IF([test $cross_compiling = no],
-          [AS_IF([TZ=UTC0 touch -t 210602070628.15 conftest.time 2>/dev/null],
-            [AS_CASE([`TZ=UTC0 LC_ALL=C ls -l conftest.time 2>/dev/null`],
-              [*'Feb  7  2106'* | *'Feb  7 17:10'*],
-              [AC_MSG_FAILURE(m4_text_wrap(
-      [this system appears to support timestamps after January 2038,
-       but no mechanism for enabling wide 'time_t' was detected.
-       Did you mean to build a 64-bit binary? (e.g. 'CC="${CC} -m64"'.)
-       To proceed with 32-bit time_t, configure with '--disable-year2038'.],
-      [], [], [55]))])])])])],
+    [ac_have_year2038=no],
 
   ["-D_TIME_BITS=64"],
     [AC_DEFINE([_TIME_BITS], [64],
       [Number of bits in time_t, on hosts where this is settable.])],
 
-  ["-D__MINGW_USE_VC2005_COMPAT=1"],
+  ["-D__MINGW_USE_VC2005_COMPAT"],
     [AC_DEFINE([__MINGW_USE_VC2005_COMPAT], [1],
       [Define to 1 on platforms where this makes time_t a 64-bit type.])],
 
   ["-U_USE_32_BIT_TIME_T"*],
     [AC_MSG_FAILURE(m4_text_wrap(
       [the 'time_t' type is currently forced to be 32-bit.
-       It will stop working after January 2038.
+       It will stop working after mid-January 2038.
        Remove _USE_32BIT_TIME_T from the compiler flags.],
       [], [], [55]))],
 
@@ -160,12 +131,11 @@ AS_CASE([$ac_cv_sys_year2038_opts],
 
 # _AC_SYS_YEAR2038_ENABLE
 # -----------------------
-# Subroutine of AC_SYS_YEAR2038 and _AC_SYS_YEAR2038_OPT_IN.
 # Depending on which of the YEAR2038 macros was used, add either an
-# --enable-year2038, or a --disable-year2038, or no option at all to
-# the configure script.  Note that this is expanded very late and
+# --enable-year2038 or a --disable-year2038 to
+# the configure script.  This is expanded very late and
 # therefore there cannot be any code in the AC_ARG_ENABLE.  The
-# default value for enable_year2038 is emitted unconditionally
+# default value for 'enable_year2038' is emitted unconditionally
 # because the generated code always looks at this variable.
 m4_define([_AC_SYS_YEAR2038_ENABLE],
 [m4_divert_text([DEFAULTS],
@@ -175,50 +145,70 @@ m4_define([_AC_SYS_YEAR2038_ENABLE],
 [AC_ARG_ENABLE([year2038],
   m4_provide_if([AC_SYS_YEAR2038],
     [AS_HELP_STRING([--disable-year2038],
-      [do not support timestamps after 2038])],
+      [don't support timestamps after 2038])],
     [AS_HELP_STRING([--enable-year2038],
       [support timestamps after 2038])]))])
 
-# _AC_SYS_YEAR2038_OPT_IN
-# -----------------------
-# If the --enable-year2038 option is given to configure, attempt to
-# detect and activate support for large time_t on 32-bit systems.
-# This macro is automatically invoked by AC_SYS_LARGEFILE when large
-# *file* support is detected.  It does not AC_REQUIRE AC_SYS_LARGEFILE
-# to avoid a dependency loop, and is therefore unsafe to expose as a
-# documented macro.
-AC_DEFUN([_AC_SYS_YEAR2038_OPT_IN],
-[m4_provide_if([_AC_SYS_YEAR2038_PROBE], [], [dnl
-  AS_IF([test "$enable_year2038" != no], [_AC_SYS_YEAR2038_PROBE])
-  AC_CONFIG_COMMANDS_PRE([_AC_SYS_YEAR2038_ENABLE])
-])])
-
 # AC_SYS_YEAR2038
 # ---------------
 # Attempt to detect and activate support for large time_t.
 # On systems where time_t is not always 64 bits, this probe can be
 # skipped by passing the --disable-year2038 option to configure.
 AC_DEFUN([AC_SYS_YEAR2038],
-[AC_REQUIRE([AC_SYS_LARGEFILE])]dnl
-[m4_provide_if([_AC_SYS_YEAR2038_PROBE], [], [dnl
-  AS_IF([test "$enable_year2038" != no], [_AC_SYS_YEAR2038_PROBE])
-  AC_CONFIG_COMMANDS_PRE([_AC_SYS_YEAR2038_ENABLE])
-])])
+[AC_REQUIRE([AC_SYS_LARGEFILE])dnl
+AS_IF([test "$enable_year2038,$ac_have_year2038,$cross_compiling" = yes,no,no],
+ [# If we're not cross compiling and 'touch' works with a large
+  # timestamp, then we can presume the system supports wider time_t
+  # *somehow* and we just weren't able to detect it.  One common
+  # case that we deliberately *don't* probe for is a system that
+  # supports both 32- and 64-bit ABIs but only the 64-bit ABI offers
+  # wide time_t.  (It would be inappropriate for us to override an
+  # intentional use of -m32.)  Error out, demanding use of
+  # --disable-year2038 if this is intentional.
+  AS_IF([TZ=UTC0 touch -t 210602070628.15 conftest.time 2>/dev/null],
+    [AS_CASE([`TZ=UTC0 LC_ALL=C ls -l conftest.time 2>/dev/null`],
+       [*'Feb  7  2106'* | *'Feb  7 17:10'*],
+       [AC_MSG_FAILURE(m4_text_wrap(
+          [this system appears to support timestamps after mid-January 2038,
+           but no mechanism for enabling wide 'time_t' was detected.
+           Did you mean to build a 64-bit binary? (E.g., 'CC="${CC} -m64"'.)
+           To proceed with 32-bit time_t, configure with '--disable-year2038'.],
+          [], [], [55]))])])])])
+
+# AC_SYS_YEAR2038_RECOMMENDED
+# ---------------------------
+# Same as AC_SYS_YEAR2038, but recommend support for large time_t.
+# If we cannot find any way to make time_t capable of representing
+# values larger than 2**31 - 1, error out unless --disable-year2038 is given.
+AC_DEFUN([AC_SYS_YEAR2038_RECOMMENDED],
+[AC_REQUIRE([AC_SYS_YEAR2038])dnl
+AS_IF([test "$enable_year2038,$ac_have_year2038" = yes,no],
+   [AC_MSG_FAILURE(m4_text_wrap(
+      [could not enable timestamps after mid-January 2038.
+       This package recommends support for these later timestamps.
+       However, to proceed with signed 32-bit time_t even though it
+       will fail then, configure with '--disable-year2038'.],
+      [], [], [55]))])])
 
 # _AC_SYS_LARGEFILE_TEST_CODE
 # ---------------------------
 # C code used to probe for large file support.
 m4_define([_AC_SYS_LARGEFILE_TEST_CODE],
 [@%:@include <sys/types.h>
- /* Check that off_t can represent 2**63 - 1 correctly.
-    We can't simply define LARGE_OFF_T to be 9223372036854775807,
+@%:@ifndef FTYPE
+@%:@ define FTYPE off_t
+@%:@endif
+ /* Check that FTYPE can represent 2**63 - 1 correctly.
+    We can't simply define LARGE_FTYPE to be 9223372036854775807,
     since some C++ compilers masquerading as C compilers
     incorrectly reject 9223372036854775807.  */
-@%:@define LARGE_OFF_T (((off_t) 1 << 31 << 31) - 1 + ((off_t) 1 << 31 << 31))
-  int off_t_is_large[[(LARGE_OFF_T % 2147483629 == 721
-                       && LARGE_OFF_T % 2147483647 == 1)
+@%:@define LARGE_FTYPE (((FTYPE) 1 << 31 << 31) - 1 + ((FTYPE) 1 << 31 << 31))
+  int FTYPE_is_large[[(LARGE_FTYPE % 2147483629 == 721
+                       && LARGE_FTYPE % 2147483647 == 1)
                       ? 1 : -1]];[]dnl
 ])
+# Defined by Autoconf 2.71 and circa 2022 Gnulib unwisely depended on it.
+m4_define([_AC_SYS_LARGEFILE_TEST_INCLUDES], [_AC_SYS_LARGEFILE_TEST_CODE])
 
 # _AC_SYS_LARGEFILE_OPTIONS
 # -------------------------
@@ -228,8 +218,7 @@ m4_define([_AC_SYS_LARGEFILE_TEST_CODE],
 m4_define([_AC_SYS_LARGEFILE_OPTIONS], m4_normalize(
     ["none needed"]                   dnl Most current systems
     ["-D_FILE_OFFSET_BITS=64"]        dnl X/Open LFS spec
-    ["-D_LARGE_FILES=1"]              dnl AIX (which versions?)
-    ["-n32"]                          dnl Irix 6.2 w/ SGI compiler
+    ["-D_LARGE_FILES=1"]              dnl 32-bit AIX 4.2.1+, 32-bit z/OS
 ))
 
 # _AC_SYS_LARGEFILE_PROBE
@@ -246,24 +235,43 @@ m4_define([_AC_SYS_LARGEFILE_OPTIONS], m4_normalize(
 # If you change this macro you may also need to change
 # _AC_SYS_LARGEFILE_OPTIONS.
 AC_DEFUN([_AC_SYS_LARGEFILE_PROBE],
-[AC_CACHE_CHECK([for $CC option to enable large file support],
+[AC_CACHE_CHECK([for $CC option to support large files],
   [ac_cv_sys_largefile_opts],
-  [ac_save_CC="$CC"
+  [ac_save_CPPFLAGS=$CPPFLAGS
   ac_opt_found=no
   for ac_opt in _AC_SYS_LARGEFILE_OPTIONS; do
     AS_IF([test x"$ac_opt" != x"none needed"],
-      [CC="$ac_save_CC $ac_opt"])
+      [CPPFLAGS="$ac_save_CPPFLAGS $ac_opt"])
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM([_AC_SYS_LARGEFILE_TEST_CODE])],
-      [ac_cv_sys_largefile_opts="$ac_opt"
+     [AS_IF([test x"$ac_opt" = x"none needed"],
+        [# GNU/Linux s390x and alpha need _FILE_OFFSET_BITS=64 for wide ino_t.
+         CPPFLAGS="$CPPFLAGS -DFTYPE=ino_t"
+         AC_COMPILE_IFELSE([], [],
+           [CPPFLAGS="$CPPFLAGS -D_FILE_OFFSET_BITS=64"
+            AC_COMPILE_IFELSE([], [ac_opt='-D_FILE_OFFSET_BITS=64'])])])
+      ac_cv_sys_largefile_opts=$ac_opt
       ac_opt_found=yes])
     test $ac_opt_found = no || break
   done
-  CC="$ac_save_CC"
+  CPPFLAGS=$ac_save_CPPFLAGS
+  dnl Gnulib implements large file support for native Windows, based on the
+  dnl variables WINDOWS_64_BIT_OFF_T, WINDOWS_64_BIT_ST_SIZE.
+  m4_ifdef([gl_LARGEFILE], [
+    AC_REQUIRE([AC_CANONICAL_HOST])
+    if test $ac_opt_found != yes; then
+      AS_CASE([$host_os],
+        [mingw* | windows*],
+          [ac_cv_sys_largefile_opts="supported through gnulib"
+           ac_opt_found=yes]
+      )
+    fi
+  ])
   test $ac_opt_found = yes || ac_cv_sys_largefile_opts="support not detected"])
 
 ac_have_largefile=yes
 AS_CASE([$ac_cv_sys_largefile_opts],
   ["none needed"], [],
+  ["supported through gnulib"], [],
   ["support not detected"],
     [ac_have_largefile=no],
 
@@ -275,45 +283,29 @@ AS_CASE([$ac_cv_sys_largefile_opts],
     [AC_DEFINE([_LARGE_FILES], [1],
       [Define to 1 on platforms where this makes off_t a 64-bit type.])],
 
-  ["-n32"],
-    [CC="$CC -n32"],
-
   [AC_MSG_ERROR(
     [internal error: bad value for \$ac_cv_sys_largefile_opts])])
 
-_AC_SYS_YEAR2038_OPT_IN
-])
-
-# _AC_SYS_LARGEFILE_ENABLE
-# ------------------------
-# Subroutine of AC_SYS_LARGEFILE.  Note that this
-# is expanded very late and therefore there cannot be any code in the
-# AC_ARG_ENABLE.  The default value for enable_largefile is emitted
-# unconditionally because the generated shell code always looks at
-# this variable.
-m4_define([_AC_SYS_LARGEFILE_ENABLE],
-[m4_divert_text([DEFAULTS],
-  enable_largefile=yes)]dnl
-[AC_ARG_ENABLE([largefile],
-  [AS_HELP_STRING([--disable-largefile], [omit support for large files])])])
+AS_IF([test "$enable_year2038" != no],
+  [_AC_SYS_YEAR2038_PROBE])
+AC_CONFIG_COMMANDS_PRE([_AC_SYS_YEAR2038_ENABLE])])
 
 # AC_SYS_LARGEFILE
 # ----------------
 # By default, many hosts won't let programs access large files;
 # one must use special compiler options to get large-file access to work.
 # For more details about this brain damage please see:
-# http://www.unix.org/version2/whatsnew/lfs20mar.html
+# https://www.unix.org/version2/whatsnew/lfs20mar.html
 # Additionally, on Linux file systems with 64-bit inodes a file that happens
 # to have a 64-bit inode number cannot be accessed by 32-bit applications on
 # Linux x86/x86_64.  This can occur with file systems such as XFS and NFS.
-# This macro allows configuration to continue if the system doesn't support
-# large files.
 AC_DEFUN([AC_SYS_LARGEFILE],
-[m4_provide_if([_AC_SYS_LARGEFILE_PROBE], [], [dnl
-  AS_IF([test "$enable_largefile" != no], [_AC_SYS_LARGEFILE_PROBE])
-  AC_CONFIG_COMMANDS_PRE([_AC_SYS_LARGEFILE_ENABLE])
-])])
-])# m4_ifndef AC_SYS_YEAR2038
+[AC_ARG_ENABLE([largefile],
+   [AS_HELP_STRING([--disable-largefile],
+      [omit support for large files])])dnl
+AS_IF([test "$enable_largefile,$enable_year2038" != no,no],
+  [_AC_SYS_LARGEFILE_PROBE])])
+])# m4_ifndef AC_SYS_YEAR2038_RECOMMENDED
 
 # Enable large files on systems where this is implemented by Gnulib, not by the
 # system headers.
@@ -323,7 +315,7 @@ AC_DEFUN([gl_LARGEFILE],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
   case "$host_os" in
-    mingw*)
+    mingw* | windows*)
       dnl Native Windows.
       dnl mingw64 defines off_t to a 64-bit type already, if
       dnl _FILE_OFFSET_BITS=64, which is ensured by AC_SYS_LARGEFILE.
diff --git a/gl/m4/libunistring-base.m4 b/gl/m4/libunistring-base.m4
new file mode 100644
index 00000000..9b5795ed
--- /dev/null
+++ b/gl/m4/libunistring-base.m4
@@ -0,0 +1,204 @@
+# libunistring-base.m4
+# serial 10
+dnl Copyright (C) 2010-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl From Paolo Bonzini and Bruno Haible.
+
+dnl gl_LIBUNISTRING_MODULE([VERSION], [Module])
+dnl Declares that the source files of Module should be compiled, unless we
+dnl are linking with libunistring and its version is >= the given VERSION.
+dnl Defines an automake conditional LIBUNISTRING_COMPILE_$MODULE that is
+dnl true if the source files of Module should be compiled.
+dnl This macro is to be used for public libunistring API, not for
+dnl undocumented API.
+dnl
+dnl You have to bump the VERSION argument to the next projected version
+dnl number each time you make a change that affects the behaviour of the
+dnl functions defined in Module (even if the sources of Module itself do not
+dnl change).
+dnl
+dnl This macro invocation must not occur in macros that are AC_REQUIREd.
+
+AC_DEFUN([gl_LIBUNISTRING_MODULE],
+[
+  AC_REQUIRE([gl_LIBUNISTRING_LIB_PREPARE])
+  dnl Use the variables HAVE_LIBUNISTRING, LIBUNISTRING_VERSION from
+  dnl gl_LIBUNISTRING_CORE if that macro has been run.
+  gl_CONDITIONAL(AS_TR_CPP([LIBUNISTRING_COMPILE_$2]),
+    [gl_LIBUNISTRING_VERSION_CMP([$1])])
+])
+
+dnl gl_LIBUNISTRING_MODULE_WITH_VARIABLE([VERSION], [Module])
+dnl is like gl_LIBUNISTRING_MODULE([VERSION], [Module]), except that it also
+dnl defines an AC_SUBSTed autoconf variable GNULIB_$MODULE_DLL_VARIABLE.
+dnl What's the expansion of this autoconf variable?
+dnl   - When building libunistring, it expands to LIBUNISTRING_DLL_VARIABLE.
+dnl     (This is necessary because this token must be present in the .h files
+dnl     when the .h files get installed.)
+dnl   - When building gnulib or application code it expands to
+dnl       - LIBUNISTRING_DLL_VARIABLE by default,
+dnl       - if the automake conditional LIBUNISTRING_COMPILE_$MODULE evaluates
+dnl         to true: the value of
+dnl         ${module_indicator_prefix}_GNULIB_LIBUNISTRING_DLL_VARIABLE_NAME
+dnl         (which usually is empty, unless explicitly set in configure.ac).
+dnl     (This is necessary because when the conditional evaluates to false,
+dnl     the application code expects to use the declared variable from the
+dnl     installed libunistring; it's in this case that the
+dnl     LIBUNISTRING_DLL_VARIABLE macro from the installed
+dnl     <unistring/woe32dll.h> must be used.)
+dnl
+dnl This macro invocation must not occur in macros that are AC_REQUIREd.
+
+AC_DEFUN([gl_LIBUNISTRING_MODULE_WITH_VARIABLE],
+[
+  gl_LIBUNISTRING_MODULE([$1], [$2])
+  m4_ifndef([gl_IN_LIBUNISTRING],
+    [if test -z "${AS_TR_CPP([LIBUNISTRING_COMPILE_$2])_TRUE}"; then
+       GL_MODULE_INDICATOR_PREFIX[]_GNULIB_[]AS_TR_CPP([$2_DLL_VARIABLE])=$GL_MODULE_INDICATOR_PREFIX[]_GNULIB_LIBUNISTRING_DLL_VARIABLE_NAME
+     fi
+    ])
+])
+
+dnl gl_LIBUNISTRING_LIBHEADER([VERSION], [HeaderFile])
+dnl Declares that HeaderFile should be created, unless we are linking
+dnl with libunistring and its version is >= the given VERSION.
+dnl HeaderFile should be relative to the lib directory and end in '.h'.
+dnl Prepares for substituting LIBUNISTRING_HEADERFILE (to HeaderFile or empty).
+dnl
+dnl When we are linking with the already installed libunistring and its version
+dnl is < VERSION, we create HeaderFile here, because we may compile functions
+dnl (via gl_LIBUNISTRING_MODULE above) that are not contained in the installed
+dnl version.
+dnl When we are linking with the already installed libunistring and its version
+dnl is > VERSION, we don't create HeaderFile here: it could cause compilation
+dnl errors in other libunistring header files if some types are missing.
+dnl
+dnl You have to bump the VERSION argument to the next projected version
+dnl number each time you make a non-comment change to the HeaderFile.
+
+AC_DEFUN([gl_LIBUNISTRING_LIBHEADER],
+[
+  AC_REQUIRE([gl_LIBUNISTRING_LIB_PREPARE])
+  dnl Use the variables HAVE_LIBUNISTRING, LIBUNISTRING_VERSION from
+  dnl gl_LIBUNISTRING_CORE if that macro has been run.
+  if gl_LIBUNISTRING_VERSION_CMP([$1]); then
+    dnl It is OK to use a .h file in lib/ from within tests/, but not vice
+    dnl versa.
+    if test -z "$LIBUNISTRING_[]AS_TR_CPP([$2])"; then
+      LIBUNISTRING_[]AS_TR_CPP([$2])="${gl_source_base_prefix}$2"
+    fi
+  else
+    LIBUNISTRING_[]AS_TR_CPP([$2])=
+  fi
+  AC_SUBST([LIBUNISTRING_]AS_TR_CPP([$2]))
+])
+
+dnl Miscellaneous preparations/initializations.
+
+AC_DEFUN([gl_LIBUNISTRING_LIB_PREPARE],
+[
+  dnl Ensure that HAVE_LIBUNISTRING is fully determined at this point.
+  m4_ifdef([gl_LIBUNISTRING], [AC_REQUIRE([gl_LIBUNISTRING])])
+
+  AC_REQUIRE([AC_PROG_AWK])
+
+dnl Sed expressions to extract the parts of a version number.
+changequote(,)
+gl_libunistring_sed_extract_major='/^[0-9]/{s/^\([0-9]*\).*/\1/p;q;}
+i\
+0
+q
+'
+gl_libunistring_sed_extract_minor='/^[0-9][0-9]*[.][0-9]/{s/^[0-9]*[.]\([0-9]*\).*/\1/p;q;}
+i\
+0
+q
+'
+gl_libunistring_sed_extract_subminor='/^[0-9][0-9]*[.][0-9][0-9]*[.][0-9]/{s/^[0-9]*[.][0-9]*[.]\([0-9]*\).*/\1/p;q;}
+i\
+0
+q
+'
+changequote([,])
+
+  if test "$HAVE_LIBUNISTRING" = yes; then
+    LIBUNISTRING_VERSION_MAJOR=`echo "$LIBUNISTRING_VERSION" | sed -n -e "$gl_libunistring_sed_extract_major"`
+    LIBUNISTRING_VERSION_MINOR=`echo "$LIBUNISTRING_VERSION" | sed -n -e "$gl_libunistring_sed_extract_minor"`
+    LIBUNISTRING_VERSION_SUBMINOR=`echo "$LIBUNISTRING_VERSION" | sed -n -e "$gl_libunistring_sed_extract_subminor"`
+  fi
+
+  dnl Determine whether <unistring/woe32dll.h> from an installed libunistring
+  dnl is available.
+  m4_ifdef([gl_IN_LIBUNISTRING],
+    [dnl In libunistring, all .h files that declare variables need to
+     dnl #include <unistring/woe32dll.h>.  This references the file
+     dnl unistring/woe32dll.h in libunistring.
+     HAVE_UNISTRING_WOE32DLL_H=1
+    ],
+    [dnl In gnulib or in applications, we need a #include <unistring/woe32dll.h>
+     dnl if and only if an installed libunistring is available.
+     if test "$HAVE_LIBUNISTRING" = yes; then
+       AC_CHECK_HEADERS([unistring/woe32dll.h],
+         [HAVE_UNISTRING_WOE32DLL_H=1],
+         [HAVE_UNISTRING_WOE32DLL_H=0])
+     else
+       HAVE_UNISTRING_WOE32DLL_H=0
+     fi
+    ])
+  AC_SUBST([HAVE_UNISTRING_WOE32DLL_H])
+])
+
+dnl gl_LIBUNISTRING_VERSION_CMP([VERSION])
+dnl Expands to a shell statement that evaluates to true if LIBUNISTRING_VERSION
+dnl is less than the VERSION argument.
+AC_DEFUN([gl_LIBUNISTRING_VERSION_CMP],
+[dnl VERSION = 999.9 means to evaluates to true always, i.e. to ignore
+dnl the installed libunistring regardless of its version.
+m4_if([$1], [999.9],
+[true],
+[ { test "$HAVE_LIBUNISTRING" != yes \
+    || {
+         dnl AS_LITERAL_IF exists and works fine since autoconf-2.59 at least.
+         AS_LITERAL_IF([$1],
+           [dnl This is the optimized variant, that assumes the argument is a literal:
+            m4_pushdef([requested_version_major],
+              [gl_LIBUNISTRING_ARG_OR_ZERO(m4_bpatsubst([$1], [^\([0-9]*\).*], [\1]), [])])
+            m4_pushdef([requested_version_minor],
+              [gl_LIBUNISTRING_ARG_OR_ZERO(m4_bpatsubst([$1], [^[0-9]*[.]\([0-9]*\).*], [\1]), [$1])])
+            m4_pushdef([requested_version_subminor],
+              [gl_LIBUNISTRING_ARG_OR_ZERO(m4_bpatsubst([$1], [^[0-9]*[.][0-9]*[.]\([0-9]*\).*], [\1]), [$1])])
+            test $LIBUNISTRING_VERSION_MAJOR -lt requested_version_major \
+            || { test $LIBUNISTRING_VERSION_MAJOR -eq requested_version_major \
+                 && { test $LIBUNISTRING_VERSION_MINOR -lt requested_version_minor \
+                      || { test $LIBUNISTRING_VERSION_MINOR -eq requested_version_minor \
+                           && test $LIBUNISTRING_VERSION_SUBMINOR -lt requested_version_subminor
+                         }
+                    }
+               }
+            m4_popdef([requested_version_subminor])
+            m4_popdef([requested_version_minor])
+            m4_popdef([requested_version_major])
+           ],
+           [dnl This is the unoptimized variant:
+            requested_version_major=`echo '$1' | sed -n -e "$gl_libunistring_sed_extract_major"`
+            requested_version_minor=`echo '$1' | sed -n -e "$gl_libunistring_sed_extract_minor"`
+            requested_version_subminor=`echo '$1' | sed -n -e "$gl_libunistring_sed_extract_subminor"`
+            test $LIBUNISTRING_VERSION_MAJOR -lt $requested_version_major \
+            || { test $LIBUNISTRING_VERSION_MAJOR -eq $requested_version_major \
+                 && { test $LIBUNISTRING_VERSION_MINOR -lt $requested_version_minor \
+                      || { test $LIBUNISTRING_VERSION_MINOR -eq $requested_version_minor \
+                           && test $LIBUNISTRING_VERSION_SUBMINOR -lt $requested_version_subminor
+                         }
+                    }
+               }
+           ])
+       }
+  }])])
+
+dnl gl_LIBUNISTRING_ARG_OR_ZERO([ARG], [ORIG]) expands to ARG if it is not the
+dnl same as ORIG, otherwise to 0.
+m4_define([gl_LIBUNISTRING_ARG_OR_ZERO], [m4_if([$1], [$2], [0], [$1])])
diff --git a/gl/m4/limits-h.m4 b/gl/m4/limits-h.m4
index 5088fa16..202df492 100644
--- a/gl/m4/limits-h.m4
+++ b/gl/m4/limits-h.m4
@@ -1,9 +1,12 @@
-dnl Check whether limits.h has needed features.
-
-dnl Copyright 2016-2023 Free Software Foundation, Inc.
+# limits-h.m4
+# serial 1
+dnl Copyright 2016-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl Check whether limits.h has needed features.
 
 dnl From Paul Eggert.
 
@@ -23,14 +26,27 @@ AC_DEFUN_ONCE([gl_LIMITS_H],
             int wb = WORD_BIT;
             int ullw = ULLONG_WIDTH;
             int bw = BOOL_WIDTH;
+            int bm = BOOL_MAX;
+            int mblm = MB_LEN_MAX;
           ]])],
        [gl_cv_header_limits_width=yes],
        [gl_cv_header_limits_width=no])])
-  if test "$gl_cv_header_limits_width" = yes; then
-    GL_GENERATE_LIMITS_H=false
-  else
-    GL_GENERATE_LIMITS_H=true
-  fi
+  GL_GENERATE_LIMITS_H=true
+  AS_IF([test "$gl_cv_header_limits_width" = yes],
+    [AC_CACHE_CHECK([whether limits.h has SSIZE_MAX],
+       [gl_cv_header_limits_ssize_max],
+       [AC_COMPILE_IFELSE(
+          [AC_LANG_SOURCE(
+             [[#include <limits.h>
+               #ifndef SSIZE_MAX
+                 #error "SSIZE_MAX is not defined"
+               #endif
+             ]])],
+          [gl_cv_header_limits_ssize_max=yes],
+          [gl_cv_header_limits_ssize_max=no])])
+     if test "$gl_cv_header_limits_ssize_max" = yes; then
+       GL_GENERATE_LIMITS_H=false
+     fi])
 ])
 
 dnl Unconditionally enables the replacement of <limits.h>.
diff --git a/gl/m4/localcharset.m4 b/gl/m4/localcharset.m4
index 15b6b2a5..374a48f1 100644
--- a/gl/m4/localcharset.m4
+++ b/gl/m4/localcharset.m4
@@ -1,8 +1,10 @@
-# localcharset.m4 serial 8
-dnl Copyright (C) 2002, 2004, 2006, 2009-2023 Free Software Foundation, Inc.
+# localcharset.m4
+# serial 8
+dnl Copyright (C) 2002, 2004, 2006, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_LOCALCHARSET],
 [
diff --git a/gl/m4/locale-en.m4 b/gl/m4/locale-en.m4
new file mode 100644
index 00000000..4151428a
--- /dev/null
+++ b/gl/m4/locale-en.m4
@@ -0,0 +1,138 @@
+# locale-en.m4
+# serial 1
+dnl Copyright (C) 2003-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl From Bruno Haible.
+
+dnl Determine the name of an English (or American English) locale with
+dnl UTF-8 encoding.
+AC_DEFUN_ONCE([gt_LOCALE_EN_UTF8],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([AM_LANGINFO_CODESET])
+  AC_CACHE_CHECK([for an english Unicode locale], [gt_cv_locale_en_utf8], [
+    case "$host_os" in
+      *-musl* | midipix*)
+        dnl On musl libc, all kinds of ll_CC.UTF-8 locales exist, even without
+        dnl any locale file on disk. But they are effectively equivalent to the
+        dnl C.UTF-8 locale, except for locale categories (such as LC_MESSSAGES)
+        dnl for which localizations (.mo files) have been installed.
+        gt_cv_locale_en_utf8=en_US.UTF-8
+        ;;
+      *)
+        AC_LANG_CONFTEST([AC_LANG_SOURCE([[
+#include <locale.h>
+#include <time.h>
+#if HAVE_LANGINFO_CODESET
+# include <langinfo.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+struct tm t;
+char buf[16];
+int main () {
+  /* On BeOS and Haiku, locales are not implemented in libc.  Rather, libintl
+     imitates locale dependent behaviour by looking at the environment
+     variables, and all locales use the UTF-8 encoding.  */
+#if !(defined __BEOS__ || defined __HAIKU__)
+  /* Check whether the given locale name is recognized by the system.  */
+# if defined _WIN32 && !defined __CYGWIN__
+  /* On native Windows, setlocale(category, "") looks at the system settings,
+     not at the environment variables.  Also, when an encoding suffix such
+     as ".65001" or ".54936" is specified, it succeeds but sets the LC_CTYPE
+     category of the locale to "C".  */
+  if (setlocale (LC_ALL, getenv ("LC_ALL")) == NULL
+      || strcmp (setlocale (LC_CTYPE, NULL), "C") == 0)
+    return 1;
+# else
+  if (setlocale (LC_ALL, "") == NULL) return 1;
+# endif
+  /* Check whether nl_langinfo(CODESET) is "UTF-8" or equivalent.  */
+# if HAVE_LANGINFO_CODESET
+  {
+    const char *cs = nl_langinfo (CODESET);
+    if (!(strcmp (cs, "UTF-8") == 0 || strcmp (cs, "UTF8") == 0
+          || strcmp (cs, "utf-8") == 0 || strcmp (cs, "utf8") == 0))
+      return 1;
+  }
+# endif
+# ifdef __CYGWIN__
+  /* On Cygwin, avoid locale names without encoding suffix, because the
+     locale_charset() function relies on the encoding suffix.  Note that
+     LC_ALL is set on the command line.  */
+  if (strchr (getenv ("LC_ALL"), '.') == NULL) return 1;
+# endif
+  /* Check the third month name.  */
+  t.tm_year = 1975 - 1900; t.tm_mon = 3 - 1; t.tm_mday = 24;
+  if (strftime (buf, sizeof (buf), "%B", &t) < 5 || strcmp (buf, "March") != 0)
+    return 1;
+#endif
+#if !defined __BIONIC__ /* Bionic libc's 'struct lconv' is just a dummy.  */
+  /* Check whether the decimal separator is a dot.  */
+  if (localeconv () ->decimal_point[0] != '.') return 1;
+#endif
+  return 0;
+}
+          ]])])
+        if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
+          case "$host_os" in
+            # Handle native Windows specially, because there setlocale() interprets
+            # "ar" or "ara" as "Arabic" or "Arabic_Saudi Arabia.1256",
+            # "en" or "eng" as "English" or "English_United States.1252",
+            # "fr" or "fra" as "French" or "French_France.1252",
+            # "ge"(!) or "deu"(!) as "German" or "German_Germany.1252",
+            # "ja" or "jpn" as "Japanese" or "Japanese_Japan.932",
+            # and similar.
+            mingw* | windows*)
+              # Test for the hypothetical native Windows locale name.
+              if (LC_ALL='English_United States.65001' LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+                gt_cv_locale_en_utf8='English_United States.65001'
+              else
+                # None found.
+                gt_cv_locale_en_utf8=none
+              fi
+              ;;
+            *)
+              # Setting LC_ALL is not enough. Need to set LC_TIME to empty, because
+              # otherwise on Mac OS X 10.3.5 the LC_TIME=C from the beginning of the
+              # configure script would override the LC_ALL setting. Likewise for
+              # LC_CTYPE, which is also set at the beginning of the configure script.
+              # Test for the locale name with explicit encoding suffix first
+              # (this is necessary on Haiku).
+              if (LC_ALL=en_US.UTF-8 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+                gt_cv_locale_en_utf8=en_US.UTF-8
+              else
+                # Test for the locale name without encoding suffix.
+                if (LC_ALL=en_US LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+                  gt_cv_locale_en_utf8=en_US
+                else
+                  # Test for the Solaris 10 locale name.
+                  if (LC_ALL=en.UTF-8 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+                    gt_cv_locale_en_utf8=en.UTF-8
+                  else
+                    # None found.
+                    gt_cv_locale_en_utf8=none
+                  fi
+                fi
+              fi
+              ;;
+          esac
+        fi
+        rm -fr conftest*
+        ;;
+    esac
+  ])
+  LOCALE_EN_UTF8="$gt_cv_locale_en_utf8"
+  case "$LOCALE_EN_UTF8" in #(
+    '' | *[[\"\$\'*@<:@]]*)
+      dnl The empty value occurs when the conftest.c program above could not
+      dnl be compiled.  The other values might cause trouble with sh or make.
+      AC_MSG_WARN([invalid locale "$LOCALE_EN_UTF8"; assuming "none"])
+      LOCALE_EN_UTF8=none;;
+  esac
+  AC_SUBST([LOCALE_EN_UTF8])
+])
diff --git a/gl/m4/locale-fr.m4 b/gl/m4/locale-fr.m4
index 8c41fadf..f504d5b5 100644
--- a/gl/m4/locale-fr.m4
+++ b/gl/m4/locale-fr.m4
@@ -1,13 +1,15 @@
-# locale-fr.m4 serial 20
-dnl Copyright (C) 2003, 2005-2023 Free Software Foundation, Inc.
+# locale-fr.m4
+# serial 24
+dnl Copyright (C) 2003, 2005-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 
 dnl Determine the name of a french locale with traditional encoding.
-AC_DEFUN([gt_LOCALE_FR],
+AC_DEFUN_ONCE([gt_LOCALE_FR],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([AM_LANGINFO_CODESET])
@@ -70,8 +72,9 @@ int main () {
   if (strftime (buf, sizeof (buf), "%b", &t) < 3 || buf[2] != 'v') return 1;
 # if !defined __BIONIC__ /* Bionic libc's 'struct lconv' is just a dummy.  */
   /* Check whether the decimal separator is a comma.
-     On NetBSD 3.0 in the fr_FR.ISO8859-1 locale, localeconv()->decimal_point
-     are nl_langinfo(RADIXCHAR) are both ".".  */
+     On NetBSD 3.0 in the fr_FR.ISO8859-1 locale
+     and on Haiku in the fr_FR.UTF-8 locale,
+     localeconv()->decimal_point are nl_langinfo(RADIXCHAR) are both ".".  */
   if (localeconv () ->decimal_point[0] != ',') return 1;
 # endif
   return 0;
@@ -81,12 +84,13 @@ int main () {
     if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
       case "$host_os" in
         # Handle native Windows specially, because there setlocale() interprets
-        # "ar" as "Arabic" or "Arabic_Saudi Arabia.1256",
+        # "ar" or "ara" as "Arabic" or "Arabic_Saudi Arabia.1256",
+        # "en" or "eng" as "English" or "English_United States.1252",
         # "fr" or "fra" as "French" or "French_France.1252",
         # "ge"(!) or "deu"(!) as "German" or "German_Germany.1252",
-        # "ja" as "Japanese" or "Japanese_Japan.932",
+        # "ja" or "jpn" as "Japanese" or "Japanese_Japan.932",
         # and similar.
-        mingw*)
+        mingw* | windows*)
           # Test for the native Windows locale name.
           if (LC_ALL=French_France.1252 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
             gt_cv_locale_fr=French_France.1252
@@ -116,7 +120,7 @@ int main () {
                 if (LC_ALL=fr_FR.iso88591 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
                   gt_cv_locale_fr=fr_FR.iso88591
                 else
-                  # Test for the Solaris 7 locale name.
+                  # Test for the Solaris 10 locale name.
                   if (LC_ALL=fr LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
                     gt_cv_locale_fr=fr
                   else
@@ -133,15 +137,31 @@ int main () {
     rm -fr conftest*
   ])
   LOCALE_FR=$gt_cv_locale_fr
+  case $LOCALE_FR in #(
+    '' | *[[[:space:]\"\$\'*@<:@]]*)
+      dnl This locale name might cause trouble with sh or make.
+      AC_MSG_WARN([invalid locale "$LOCALE_FR"; assuming "none"])
+      LOCALE_FR=none;;
+  esac
   AC_SUBST([LOCALE_FR])
 ])
 
 dnl Determine the name of a french locale with UTF-8 encoding.
-AC_DEFUN([gt_LOCALE_FR_UTF8],
+AC_DEFUN_ONCE([gt_LOCALE_FR_UTF8],
 [
+  AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([AM_LANGINFO_CODESET])
   AC_CACHE_CHECK([for a french Unicode locale], [gt_cv_locale_fr_utf8], [
-    AC_LANG_CONFTEST([AC_LANG_SOURCE([[
+    case "$host_os" in
+      *-musl* | midipix*)
+        dnl On musl libc, all kinds of ll_CC.UTF-8 locales exist, even without
+        dnl any locale file on disk. But they are effectively equivalent to the
+        dnl C.UTF-8 locale, except for locale categories (such as LC_MESSSAGES)
+        dnl for which localizations (.mo files) have been installed.
+        gt_cv_locale_fr_utf8=fr_FR.UTF-8
+        ;;
+      *)
+        AC_LANG_CONFTEST([AC_LANG_SOURCE([[
 #include <locale.h>
 #include <time.h>
 #if HAVE_LANGINFO_CODESET
@@ -197,57 +217,90 @@ int main () {
 #endif
 #if !defined __BIONIC__ /* Bionic libc's 'struct lconv' is just a dummy.  */
   /* Check whether the decimal separator is a comma.
-     On NetBSD 3.0 in the fr_FR.ISO8859-1 locale, localeconv()->decimal_point
-     are nl_langinfo(RADIXCHAR) are both ".".  */
+     On NetBSD 3.0 in the fr_FR.ISO8859-1 locale
+     and on Haiku in the fr_FR.UTF-8 locale,
+     localeconv()->decimal_point are nl_langinfo(RADIXCHAR) are both ".".  */
   if (localeconv () ->decimal_point[0] != ',') return 1;
 #endif
   return 0;
 }
-      ]])])
-    if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
-      case "$host_os" in
-        # Handle native Windows specially, because there setlocale() interprets
-        # "ar" as "Arabic" or "Arabic_Saudi Arabia.1256",
-        # "fr" or "fra" as "French" or "French_France.1252",
-        # "ge"(!) or "deu"(!) as "German" or "German_Germany.1252",
-        # "ja" as "Japanese" or "Japanese_Japan.932",
-        # and similar.
-        mingw*)
-          # Test for the hypothetical native Windows locale name.
-          if (LC_ALL=French_France.65001 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
-            gt_cv_locale_fr_utf8=French_France.65001
-          else
-            # None found.
-            gt_cv_locale_fr_utf8=none
-          fi
-          ;;
-        *)
-          # Setting LC_ALL is not enough. Need to set LC_TIME to empty, because
-          # otherwise on Mac OS X 10.3.5 the LC_TIME=C from the beginning of the
-          # configure script would override the LC_ALL setting. Likewise for
-          # LC_CTYPE, which is also set at the beginning of the configure script.
-          # Test for the usual locale name.
-          if (LC_ALL=fr_FR LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
-            gt_cv_locale_fr_utf8=fr_FR
-          else
-            # Test for the locale name with explicit encoding suffix.
-            if (LC_ALL=fr_FR.UTF-8 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
-              gt_cv_locale_fr_utf8=fr_FR.UTF-8
-            else
-              # Test for the Solaris 7 locale name.
-              if (LC_ALL=fr.UTF-8 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
-                gt_cv_locale_fr_utf8=fr.UTF-8
+          ]])])
+        if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
+          case "$host_os" in
+            # Handle native Windows specially, because there setlocale() interprets
+            # "ar" or "ara" as "Arabic" or "Arabic_Saudi Arabia.1256",
+            # "en" or "eng" as "English" or "English_United States.1252",
+            # "fr" or "fra" as "French" or "French_France.1252",
+            # "ge"(!) or "deu"(!) as "German" or "German_Germany.1252",
+            # "ja" or "jpn" as "Japanese" or "Japanese_Japan.932",
+            # and similar.
+            mingw* | windows*)
+              # Test for the hypothetical native Windows locale name.
+              if (LC_ALL=French_France.65001 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+                gt_cv_locale_fr_utf8=French_France.65001
               else
                 # None found.
                 gt_cv_locale_fr_utf8=none
               fi
-            fi
-          fi
-          ;;
-      esac
-    fi
-    rm -fr conftest*
+              ;;
+            *)
+              # Setting LC_ALL is not enough. Need to set LC_TIME to empty, because
+              # otherwise on Mac OS X 10.3.5 the LC_TIME=C from the beginning of the
+              # configure script would override the LC_ALL setting. Likewise for
+              # LC_CTYPE, which is also set at the beginning of the configure script.
+              # Test for the usual locale name.
+              if (LC_ALL=fr_FR LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+                gt_cv_locale_fr_utf8=fr_FR
+              else
+                # Test for the locale name with explicit encoding suffix.
+                if (LC_ALL=fr_FR.UTF-8 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+                  gt_cv_locale_fr_utf8=fr_FR.UTF-8
+                else
+                  # Test for the Solaris 10 locale name.
+                  if (LC_ALL=fr.UTF-8 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+                    gt_cv_locale_fr_utf8=fr.UTF-8
+                  else
+                    # None found.
+                    gt_cv_locale_fr_utf8=none
+                  fi
+                fi
+              fi
+              ;;
+          esac
+        fi
+        rm -fr conftest*
+        ;;
+    esac
   ])
   LOCALE_FR_UTF8=$gt_cv_locale_fr_utf8
+  case $LOCALE_FR_UTF8 in #(
+    '' | *[[[:space:]\"\$\'*@<:@]]*)
+      dnl This locale name might cause trouble with sh or make.
+      AC_MSG_WARN([invalid locale "$LOCALE_FR_UTF8"; assuming "none"])
+      LOCALE_FR_UTF8=none;;
+  esac
   AC_SUBST([LOCALE_FR_UTF8])
+
+  dnl Users of $LOCALE_FR_UTF8 need to know which of the locale categories they
+  dnl can rely on.
+  case "$host_os" in
+    *-musl* | midipix*)
+      dnl On musl libc, locale categories other than LC_CTYPE and LC_MESSAGES
+      dnl are effectively unimplemented.
+      LC_COLLATE_IMPLEMENTED=false
+      LC_NUMERIC_IMPLEMENTED=false
+      LC_TIME_IMPLEMENTED=false
+      LC_MONETARY_IMPLEMENTED=false
+      ;;
+    *)
+      LC_COLLATE_IMPLEMENTED=true
+      LC_NUMERIC_IMPLEMENTED=true
+      LC_TIME_IMPLEMENTED=true
+      LC_MONETARY_IMPLEMENTED=true
+      ;;
+  esac
+  AC_SUBST([LC_COLLATE_IMPLEMENTED])
+  AC_SUBST([LC_NUMERIC_IMPLEMENTED])
+  AC_SUBST([LC_TIME_IMPLEMENTED])
+  AC_SUBST([LC_MONETARY_IMPLEMENTED])
 ])
diff --git a/gl/m4/locale-ja.m4 b/gl/m4/locale-ja.m4
index 25901730..1c813b89 100644
--- a/gl/m4/locale-ja.m4
+++ b/gl/m4/locale-ja.m4
@@ -1,13 +1,15 @@
-# locale-ja.m4 serial 15
-dnl Copyright (C) 2003, 2005-2023 Free Software Foundation, Inc.
+# locale-ja.m4
+# serial 19
+dnl Copyright (C) 2003, 2005-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 
 dnl Determine the name of a japanese locale with EUC-JP encoding.
-AC_DEFUN([gt_LOCALE_JA],
+AC_DEFUN_ONCE([gt_LOCALE_JA],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([AM_LANGINFO_CODESET])
@@ -85,12 +87,13 @@ int main ()
     if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
       case "$host_os" in
         # Handle native Windows specially, because there setlocale() interprets
-        # "ar" as "Arabic" or "Arabic_Saudi Arabia.1256",
+        # "ar" or "ara" as "Arabic" or "Arabic_Saudi Arabia.1256",
+        # "en" or "eng" as "English" or "English_United States.1252",
         # "fr" or "fra" as "French" or "French_France.1252",
         # "ge"(!) or "deu"(!) as "German" or "German_Germany.1252",
-        # "ja" as "Japanese" or "Japanese_Japan.932",
+        # "ja" or "jpn" as "Japanese" or "Japanese_Japan.932",
         # and similar.
-        mingw*)
+        mingw* | windows*)
           # Note that on native Windows, the Japanese locale is
           # Japanese_Japan.932, and CP932 is very different from EUC-JP, so we
           # cannot use it here.
@@ -117,7 +120,7 @@ int main ()
                 if (LC_ALL=ja_JP.EUC LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
                   gt_cv_locale_ja=ja_JP.EUC
                 else
-                  # Test for the Solaris 7 locale name.
+                  # Test for the Solaris 10 locale name.
                   if (LC_ALL=ja LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
                     gt_cv_locale_ja=ja
                   else
@@ -139,5 +142,11 @@ int main ()
     rm -fr conftest*
   ])
   LOCALE_JA=$gt_cv_locale_ja
+  case $LOCALE_JA in #(
+    '' | *[[[:space:]\"\$\'*@<:@]]*)
+      dnl This locale name might cause trouble with sh or make.
+      AC_MSG_WARN([invalid locale "$LOCALE_JA"; assuming "none"])
+      LOCALE_JA=none;;
+  esac
   AC_SUBST([LOCALE_JA])
 ])
diff --git a/gl/m4/locale-zh.m4 b/gl/m4/locale-zh.m4
index b9f9eef7..6f9374d2 100644
--- a/gl/m4/locale-zh.m4
+++ b/gl/m4/locale-zh.m4
@@ -1,13 +1,15 @@
-# locale-zh.m4 serial 15
-dnl Copyright (C) 2003, 2005-2023 Free Software Foundation, Inc.
+# locale-zh.m4
+# serial 20
+dnl Copyright (C) 2003, 2005-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 
 dnl Determine the name of a chinese locale with GB18030 encoding.
-AC_DEFUN([gt_LOCALE_ZH_CN],
+AC_DEFUN_ONCE([gt_LOCALE_ZH_CN],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([AM_LANGINFO_CODESET])
@@ -21,6 +23,7 @@ AC_DEFUN([gt_LOCALE_ZH_CN],
 #endif
 #include <stdlib.h>
 #include <string.h>
+#include <wchar.h>
 struct tm t;
 char buf[16];
 int main ()
@@ -79,6 +82,19 @@ int main ()
      single wide character.  This excludes the GB2312 and GBK encodings.  */
   if (mblen ("\203\062\332\066", 5) != 4)
     return 1;
+  /* Check whether mbrtowc accept this character one byte at a time.
+     This excludes NetBSD 10.0.  */
+  if (sizeof (wchar_t) > 2)
+    {
+      wchar_t wc;
+      mbstate_t state;
+      memset (&state, 0, sizeof (state));
+      if (!(mbrtowc (&wc, "\203", 1, &state) == (size_t)(-2)
+            && mbrtowc (&wc, "\062", 1, &state) == (size_t)(-2)
+            && mbrtowc (&wc, "\332", 1, &state) == (size_t)(-2)
+            && mbrtowc (&wc, "\066", 1, &state) == 1))
+        return 1;
+    }
   return 0;
 #endif
 }
@@ -86,12 +102,13 @@ int main ()
     if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
       case "$host_os" in
         # Handle native Windows specially, because there setlocale() interprets
-        # "ar" as "Arabic" or "Arabic_Saudi Arabia.1256",
+        # "ar" or "ara" as "Arabic" or "Arabic_Saudi Arabia.1256",
+        # "en" or "eng" as "English" or "English_United States.1252",
         # "fr" or "fra" as "French" or "French_France.1252",
         # "ge"(!) or "deu"(!) as "German" or "German_Germany.1252",
-        # "ja" as "Japanese" or "Japanese_Japan.932",
+        # "ja" or "jpn" as "Japanese" or "Japanese_Japan.932",
         # and similar.
-        mingw*)
+        mingw* | windows*)
           # Test for the hypothetical native Windows locale name.
           if (LC_ALL=Chinese_China.54936 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
             gt_cv_locale_zh_CN=Chinese_China.54936
@@ -133,5 +150,11 @@ int main ()
     rm -fr conftest*
   ])
   LOCALE_ZH_CN=$gt_cv_locale_zh_CN
+  case $LOCALE_ZH_CN in #(
+    '' | *[[[:space:]\"\$\'*@<:@]]*)
+      dnl This locale name might cause trouble with sh or make.
+      AC_MSG_WARN([invalid locale "$LOCALE_ZH_CN"; assuming "none"])
+      LOCALE_ZH_CN=none;;
+  esac
   AC_SUBST([LOCALE_ZH_CN])
 ])
diff --git a/gl/m4/locale_h.m4 b/gl/m4/locale_h.m4
index a33a0a46..e1afbc16 100644
--- a/gl/m4/locale_h.m4
+++ b/gl/m4/locale_h.m4
@@ -1,8 +1,10 @@
-# locale_h.m4 serial 28
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# locale_h.m4
+# serial 37
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_LOCALE_H],
 [
@@ -18,6 +20,26 @@ AC_DEFUN_ONCE([gl_LOCALE_H],
   AC_REQUIRE([gl_STDDEF_H])
 
   AC_REQUIRE([gl_LOCALE_T])
+  dnl On native Windows, there is a type '_locale_t' that can be used to
+  dnl define locale_t.
+  AC_CACHE_CHECK([whether locale.h defines _locale_t],
+    [gl_cv_header_locale_has_windows_locale_t],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <locale.h>
+            _locale_t x;]],
+          [[]])],
+       [gl_cv_header_locale_has_windows_locale_t=yes],
+       [gl_cv_header_locale_has_windows_locale_t=no])
+    ])
+  if test $gl_cv_header_locale_has_windows_locale_t = yes; then
+    HAVE_WINDOWS_LOCALE_T=1
+    AC_DEFINE([HAVE_WINDOWS_LOCALE_T], [1],
+      [Define to 1 if <locale.h> defines the _locale_t type.])
+  else
+    HAVE_WINDOWS_LOCALE_T=0
+  fi
+  AC_SUBST([HAVE_WINDOWS_LOCALE_T])
 
   dnl Solaris 11.0 defines the int_p_*, int_n_* members of 'struct lconv'
   dnl only if _LCONV_C99 is defined.
@@ -59,7 +81,9 @@ AC_DEFUN_ONCE([gl_LOCALE_H],
     dnl On native Windows with MSVC, merely define these member names as macros.
     dnl This avoids trouble in C++ mode.
     case "$host_os" in
-      mingw*)
+      windows*-msvc*)
+        ;;
+      mingw* | windows*)
         AC_EGREP_CPP([Special], [
 #ifdef _MSC_VER
  Special
@@ -83,7 +107,7 @@ AC_DEFUN_ONCE([gl_LOCALE_H],
 # include <xlocale.h>
 #endif
     ]],
-    [setlocale newlocale duplocale freelocale])
+    [setlocale newlocale duplocale freelocale getlocalename_l])
 ])
 
 dnl Checks to determine whether the system has the locale_t type,
@@ -127,6 +151,7 @@ AC_DEFUN([gl_LOCALE_T],
     fi
   fi
   AC_SUBST([HAVE_XLOCALE_H])
+  AC_SUBST([HAVE_LOCALE_T])
 ])
 
 # gl_LOCALE_MODULE_INDICATOR([modulename])
@@ -151,8 +176,12 @@ AC_DEFUN([gl_LOCALE_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOCALECONV])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETLOCALE])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETLOCALE_NULL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_NEWLOCALE])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DUPLOCALE])
-    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOCALENAME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREELOCALE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETLOCALENAME_L])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETLOCALENAME_L_UNSAFE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOCALENAME_UNSAFE])
   ])
   m4_require(GL_MODULE_INDICATOR_PREFIX[_LOCALE_H_MODULE_INDICATOR_DEFAULTS])
   AC_REQUIRE([gl_LOCALE_H_DEFAULTS])
@@ -161,14 +190,16 @@ AC_DEFUN([gl_LOCALE_H_REQUIRE_DEFAULTS],
 AC_DEFUN([gl_LOCALE_H_DEFAULTS],
 [
   dnl Assume proper GNU behavior unless another module says otherwise.
-  HAVE_NEWLOCALE=1;       AC_SUBST([HAVE_NEWLOCALE])
-  HAVE_DUPLOCALE=1;       AC_SUBST([HAVE_DUPLOCALE])
-  HAVE_FREELOCALE=1;      AC_SUBST([HAVE_FREELOCALE])
-  REPLACE_LOCALECONV=0;   AC_SUBST([REPLACE_LOCALECONV])
-  REPLACE_SETLOCALE=0;    AC_SUBST([REPLACE_SETLOCALE])
-  REPLACE_NEWLOCALE=0;    AC_SUBST([REPLACE_NEWLOCALE])
-  REPLACE_DUPLOCALE=0;    AC_SUBST([REPLACE_DUPLOCALE])
-  REPLACE_FREELOCALE=0;   AC_SUBST([REPLACE_FREELOCALE])
-  REPLACE_STRUCT_LCONV=0; AC_SUBST([REPLACE_STRUCT_LCONV])
+  HAVE_NEWLOCALE=1;          AC_SUBST([HAVE_NEWLOCALE])
+  HAVE_DUPLOCALE=1;          AC_SUBST([HAVE_DUPLOCALE])
+  HAVE_FREELOCALE=1;         AC_SUBST([HAVE_FREELOCALE])
+  HAVE_GETLOCALENAME_L=1;    AC_SUBST([HAVE_GETLOCALENAME_L])
+  REPLACE_LOCALECONV=0;      AC_SUBST([REPLACE_LOCALECONV])
+  REPLACE_SETLOCALE=0;       AC_SUBST([REPLACE_SETLOCALE])
+  REPLACE_NEWLOCALE=0;       AC_SUBST([REPLACE_NEWLOCALE])
+  REPLACE_DUPLOCALE=0;       AC_SUBST([REPLACE_DUPLOCALE])
+  REPLACE_FREELOCALE=0;      AC_SUBST([REPLACE_FREELOCALE])
+  REPLACE_GETLOCALENAME_L=0; AC_SUBST([REPLACE_GETLOCALENAME_L])
+  REPLACE_STRUCT_LCONV=0;    AC_SUBST([REPLACE_STRUCT_LCONV])
   LOCALENAME_ENHANCE_LOCALE_FUNCS=0; AC_SUBST([LOCALENAME_ENHANCE_LOCALE_FUNCS])
 ])
diff --git a/gl/m4/localeconv.m4 b/gl/m4/localeconv.m4
index ae225fed..55a669d0 100644
--- a/gl/m4/localeconv.m4
+++ b/gl/m4/localeconv.m4
@@ -1,17 +1,54 @@
-# localeconv.m4 serial 1
-dnl Copyright (C) 2012-2023 Free Software Foundation, Inc.
+# localeconv.m4
+# serial 3
+dnl Copyright (C) 2012-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_LOCALECONV],
 [
   AC_REQUIRE([gl_LOCALE_H_DEFAULTS])
   AC_REQUIRE([gl_LOCALE_H])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
 
   if test $REPLACE_STRUCT_LCONV = 1; then
     REPLACE_LOCALECONV=1
   fi
+  if test $REPLACE_LOCALECONV = 0; then
+    dnl Test whether fields of type 'char' are filled correctly.
+    dnl This test fails on mingw 5.0.3.
+    AC_CACHE_CHECK([whether localeconv works],
+      [gl_cv_func_localeconv_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE([[
+            #include <locale.h>
+            #include <limits.h>
+            int main ()
+            {
+              struct lconv *l = localeconv ();
+              return l->frac_digits != CHAR_MAX && l->frac_digits < 0;
+            }
+         ]])],
+         [gl_cv_func_localeconv_works=yes],
+         [gl_cv_func_localeconv_works=no],
+         [case "$host_os" in
+                                # Guess yes on glibc systems.
+            *-gnu* | gnu*)      gl_cv_func_localeconv_works="guessing yes" ;;
+                                # Guess yes on musl systems.
+            *-musl* | midipix*) gl_cv_func_localeconv_works="guessing yes" ;;
+                                # Guess no on native Windows.
+            mingw* | windows*)  gl_cv_func_localeconv_works="guessing no" ;;
+                                # If we don't know, obey --enable-cross-guesses.
+            *)                  gl_cv_func_localeconv_works="$gl_cross_guess_normal" ;;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_localeconv_works" in
+      *yes) ;;
+      *) REPLACE_LOCALECONV=1 ;;
+    esac
+  fi
 ])
 
 # Prerequisites of lib/localeconv.c.
@@ -19,4 +56,6 @@ AC_DEFUN([gl_PREREQ_LOCALECONV],
 [
   AC_CHECK_MEMBERS([struct lconv.decimal_point], [], [],
     [[#include <locale.h>]])
+  AC_CHECK_MEMBERS([struct lconv.int_p_cs_precedes], [], [],
+    [[#include <locale.h>]])
 ])
diff --git a/gl/m4/lock.m4 b/gl/m4/lock.m4
index 88cf5575..b1d3f435 100644
--- a/gl/m4/lock.m4
+++ b/gl/m4/lock.m4
@@ -1,8 +1,10 @@
-# lock.m4 serial 14
-dnl Copyright (C) 2005-2023 Free Software Foundation, Inc.
+# lock.m4
+# serial 14
+dnl Copyright (C) 2005-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 
diff --git a/gl/m4/lseek.m4 b/gl/m4/lseek.m4
index fd4f1f27..ddfadd38 100644
--- a/gl/m4/lseek.m4
+++ b/gl/m4/lseek.m4
@@ -1,8 +1,10 @@
-# lseek.m4 serial 12
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# lseek.m4
+# serial 15
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_LSEEK],
 [
@@ -13,13 +15,15 @@ AC_DEFUN([gl_FUNC_LSEEK],
   AC_CHECK_HEADERS_ONCE([unistd.h])
   AC_CACHE_CHECK([whether lseek detects pipes], [gl_cv_func_lseek_pipe],
     [case "$host_os" in
-       mingw*)
+       mingw* | windows*)
          dnl Native Windows.
          dnl The result of lseek (fd, (off_t)0, SEEK_CUR) or
          dnl SetFilePointer(handle, 0, NULL, FILE_CURRENT)
-         dnl for a pipe depends on the environment: In a Cygwin 1.5
-         dnl environment it succeeds (wrong); in a Cygwin 1.7 environment
-         dnl it fails with a wrong errno value.
+         dnl for a pipe depends on the environment:
+         dnl In a Cygwin 1.5 environment it succeeds (wrong);
+         dnl in a Cygwin 1.7 environment it fails with a wrong errno value;
+         dnl in a Cygwin 2.9.0 environment it fails correctly;
+         dnl in a Cygwin 3.4.6 environment it succeeds again (wrong).
          gl_cv_func_lseek_pipe=no
          ;;
        *)
@@ -70,9 +74,29 @@ AC_DEFUN([gl_FUNC_LSEEK],
     REPLACE_LSEEK=1
   fi
 
-  dnl macOS SEEK_DATA is incompatible with other platforms.
-  case $host_os in
-    darwin*)
-      REPLACE_LSEEK=1;;
-  esac
+  AS_IF([test $REPLACE_LSEEK = 0],
+    [AC_CACHE_CHECK([whether SEEK_DATA works but is incompatible with GNU],
+       [gl_cv_func_lseek_works_but_incompatible],
+       [AC_PREPROC_IFELSE(
+          [AC_LANG_SOURCE(
+             dnl Use macOS "9999" to stand for a future fixed macOS version.
+             dnl See ../lib/unistd.in.h and <https://bugs.gnu.org/61386>.
+             [[#include <unistd.h>
+               #if defined __APPLE__ && defined __MACH__ && defined SEEK_DATA
+               # ifdef __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__
+               #  include <AvailabilityMacros.h>
+               # endif
+               # if 99990000 <= MAC_OS_X_VERSION_MIN_REQUIRED
+               #  define LSEEK_WORKS_BUT_IS_INCOMPATIBLE_WITH_GNU
+               # endif
+               #endif
+               #ifndef LSEEK_WORKS_BUT_IS_INCOMPATIBLE_WITH_GNU
+                #error "No need to work around the bug"
+               #endif
+             ]])],
+          [gl_cv_func_lseek_works_but_incompatible=yes],
+          [gl_cv_func_lseek_works_but_incompatible=no])])
+     if test "$gl_cv_func_lseek_works_but_incompatible" = yes; then
+       REPLACE_LSEEK=1
+     fi])
 ])
diff --git a/gl/m4/lstat.m4 b/gl/m4/lstat.m4
new file mode 100644
index 00000000..efae2485
--- /dev/null
+++ b/gl/m4/lstat.m4
@@ -0,0 +1,82 @@
+# lstat.m4
+# serial 36
+dnl Copyright (C) 1997-2001, 2003-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl From Jim Meyering.
+
+AC_DEFUN([gl_FUNC_LSTAT],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
+  dnl If lstat does not exist, the replacement <sys/stat.h> does
+  dnl "#define lstat stat", and lstat.c is a no-op.
+  AC_CHECK_FUNCS_ONCE([lstat])
+  if test $ac_cv_func_lstat = yes; then
+    AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+    case $host_os,$gl_cv_func_lstat_dereferences_slashed_symlink in
+      darwin* | solaris* | *no)
+        REPLACE_LSTAT=1
+        ;;
+    esac
+  else
+    HAVE_LSTAT=0
+  fi
+])
+
+# Prerequisites of lib/lstat.c.
+AC_DEFUN([gl_PREREQ_LSTAT], [:])
+
+AC_DEFUN([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK],
+[
+  dnl We don't use AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK any more, because it
+  dnl is no longer maintained in Autoconf and because it invokes AC_LIBOBJ.
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether lstat correctly handles trailing slash],
+    [gl_cv_func_lstat_dereferences_slashed_symlink],
+    [rm -f conftest.sym conftest.file
+     echo >conftest.file
+     AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [AC_INCLUDES_DEFAULT],
+          [[struct stat sbuf;
+            if (symlink ("conftest.file", "conftest.sym") != 0)
+              return 1;
+            /* Linux will dereference the symlink and fail, as required by
+               POSIX.  That is better in the sense that it means we will not
+               have to compile and use the lstat wrapper.  */
+            return lstat ("conftest.sym/", &sbuf) == 0;
+          ]])],
+       [gl_cv_func_lstat_dereferences_slashed_symlink=yes],
+       [gl_cv_func_lstat_dereferences_slashed_symlink=no],
+       [case "$host_os" in
+          linux-* | linux)
+            # Guess yes on Linux systems.
+            gl_cv_func_lstat_dereferences_slashed_symlink="guessing yes" ;;
+          midipix*)
+            # Guess yes on systems that emulate the Linux system calls.
+            gl_cv_func_lstat_dereferences_slashed_symlink="guessing yes" ;;
+          *-gnu* | gnu*)
+            # Guess yes on glibc systems.
+            gl_cv_func_lstat_dereferences_slashed_symlink="guessing yes" ;;
+          mingw* | windows*)
+            # Guess no on native Windows.
+            gl_cv_func_lstat_dereferences_slashed_symlink="guessing no" ;;
+          *)
+            # If we don't know, obey --enable-cross-guesses.
+            gl_cv_func_lstat_dereferences_slashed_symlink="$gl_cross_guess_normal" ;;
+        esac
+       ])
+     rm -f conftest.sym conftest.file
+    ])
+  case "$gl_cv_func_lstat_dereferences_slashed_symlink" in
+    *yes)
+      AC_DEFINE_UNQUOTED([LSTAT_FOLLOWS_SLASHED_SYMLINK], [1],
+        [Define to 1 if 'lstat' dereferences a symlink specified
+         with a trailing slash.])
+      ;;
+  esac
+])
diff --git a/gl/m4/malloc.m4 b/gl/m4/malloc.m4
index 55402924..547b4e4d 100644
--- a/gl/m4/malloc.m4
+++ b/gl/m4/malloc.m4
@@ -1,11 +1,24 @@
-# malloc.m4 serial 28
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# malloc.m4
+# serial 43.1
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# This is adapted with modifications from upstream Autoconf here:
-# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=v2.70#n949
+m4_version_prereq([2.73], [], [
+# Modules that use this macro directly or indirectly should depend
+# on extensions-aix, so that _LINUX_SOURCE_COMPAT gets defined
+# before this macro gets invoked.  This helps on AIX 7.2 and earlier
+# if !(__VEC__ || __AIXVEC), and doesn't hurt otherwise.
+#
+# This is copied from upstream Autoconf here:
+# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=1f38316f6af7bf63e5e7dd187ff6456e07ad743e#n971
+# _AC_FUNC_MALLOC_IF(IF-WORKS, IF-NOT[, UNKNOWN-ASSUME])
+# ------------------------------------------------------
+# If 'malloc (0)' returns nonnull, run IF-WORKS, otherwise, IF-NOT.
+# If it is not known whether it works, assume the shell word UNKNOWN-ASSUME,
+# which should end in "yes" or in something else (the latter is the default).
 AC_DEFUN([_AC_FUNC_MALLOC_IF],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
@@ -14,55 +27,81 @@ AC_DEFUN([_AC_FUNC_MALLOC_IF],
     [AC_RUN_IFELSE(
        [AC_LANG_PROGRAM(
           [[#include <stdlib.h>
-          ]],
-          [[void *p = malloc (0);
+            /* Use pmalloc to test; 'volatile' prevents the compiler
+               from optimizing the malloc call away.  */
+            void *(*volatile pmalloc) (size_t) = malloc;]],
+          [[void *p = pmalloc (0);
             int result = !p;
             free (p);
-            return result;]])
-       ],
+            return result;]])],
        [ac_cv_func_malloc_0_nonnull=yes],
        [ac_cv_func_malloc_0_nonnull=no],
-       [case "$host_os" in
-          # Guess yes on platforms where we know the result.
-          *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
-          | gnu* | *-musl* | midnightbsd* \
-          | hpux* | solaris* | cygwin* | mingw* | msys* )
-            ac_cv_func_malloc_0_nonnull="guessing yes" ;;
-          # If we don't know, obey --enable-cross-guesses.
-          *) ac_cv_func_malloc_0_nonnull="$gl_cross_guess_normal" ;;
-        esac
-       ])
-    ])
+       [AS_CASE([$host_os],
+          [# Guess yes on platforms where we know the result.
+           *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
+           | gnu* | *-musl* | midipix* | midnightbsd* \
+           | hpux* | solaris* | cygwin* | mingw* | windows* | msys*],
+            [ac_cv_func_malloc_0_nonnull="guessing yes"],
+          [# Guess as follows if we don't know.
+           ac_cv_func_malloc_0_nonnull=m4_default([$3], ["guessing no"])])])])
   AS_CASE([$ac_cv_func_malloc_0_nonnull], [*yes], [$1], [$2])
 ])# _AC_FUNC_MALLOC_IF
+])
+
+# gl_FUNC_MALLOC_0_NONNULL
+# ------------------------
+# If 'malloc (0)' returns nonnull define HAVE_MALLOC_0_NONNULL.
+# Also, set ac_cv_func_malloc_0_nonnull to a string that ends in
+# "yes", otherwise set it to something else.  If unknown whether
+# malloc (0) works, guess as normal for cross-builds.
+AC_DEFUN([gl_FUNC_MALLOC_0_NONNULL],
+[
+  _AC_FUNC_MALLOC_IF(
+    [AC_DEFINE([HAVE_MALLOC_0_NONNULL], [1],
+       [Define to 1 if malloc (0) returns nonnull.])],
+    [],
+    ["$gl_cross_guess_normal"])
+])
 
 # gl_FUNC_MALLOC_GNU
 # ------------------
-# Replace malloc if it is not compatible with GNU libc.
+# Test whether malloc (0) is compatible with GNU libc.
+# Replace malloc if not.
+# Define HAVE_MALLOC_0_NONNULL if malloc (0) returns nonnull (except upon
+# out-of-memory).
+# Define HAVE_MALLOC_PTRDIFF if malloc (N) reliably fails when N exceeds
+# PTRDIFF_MAX.
 AC_DEFUN([gl_FUNC_MALLOC_GNU],
 [
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
-  REPLACE_MALLOC_FOR_MALLOC_GNU="$REPLACE_MALLOC_FOR_MALLOC_POSIX"
-  if test $REPLACE_MALLOC_FOR_MALLOC_GNU = 0; then
-    _AC_FUNC_MALLOC_IF([], [REPLACE_MALLOC_FOR_MALLOC_GNU=1])
-  fi
+  AC_REQUIRE([gl_FUNC_MALLOC_0_NONNULL])
+
+  AS_CASE([$ac_cv_func_malloc_0_nonnull],
+    [*yes],
+      [REPLACE_MALLOC_FOR_MALLOC_GNU=$REPLACE_MALLOC_FOR_MALLOC_POSIX],
+    [REPLACE_MALLOC_FOR_MALLOC_GNU=1])
 ])
 
 # gl_FUNC_MALLOC_PTRDIFF
 # ----------------------
-# Test whether malloc (N) reliably fails when N exceeds PTRDIFF_MAX,
-# and replace malloc otherwise.
+# Test whether malloc (N) reliably fails when N exceeds PTRDIFF_MAX.
+# Define HAVE_MALLOC_PTRDIFF if yes.
+# Replace malloc if not.
 AC_DEFUN([gl_FUNC_MALLOC_PTRDIFF],
 [
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
   AC_REQUIRE([gl_CHECK_MALLOC_PTRDIFF])
-  test "$gl_cv_malloc_ptrdiff" = yes || REPLACE_MALLOC_FOR_MALLOC_POSIX=1
+  AS_IF([test "$gl_cv_malloc_ptrdiff" = yes],
+    [AC_DEFINE([HAVE_MALLOC_PTRDIFF], 1,
+       [Define to 1 if malloc-like functions do not allocate objects
+        larger than PTRDIFF_MAX bytes.])],
+    [REPLACE_MALLOC_FOR_MALLOC_POSIX=1])
 ])
 
-# Test whether malloc, realloc, calloc refuse to create objects
+# Test whether malloc, calloc refuse to create objects
 # larger than what can be expressed in ptrdiff_t.
-# Set gl_cv_func_malloc_gnu to yes or no accordingly.
+# Set gl_cv_func_malloc_gnu.
 AC_DEFUN([gl_CHECK_MALLOC_PTRDIFF],
 [
   AC_CACHE_CHECK([whether malloc is ptrdiff_t safe],
@@ -106,30 +145,48 @@ AC_DEFUN([gl_FUNC_MALLOC_POSIX],
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_MALLOC_PTRDIFF])
   AC_REQUIRE([gl_CHECK_MALLOC_POSIX])
-  if test "$gl_cv_func_malloc_posix" = yes; then
-    AC_DEFINE([HAVE_MALLOC_POSIX], [1],
-      [Define if malloc, realloc, and calloc set errno on allocation failure.])
-  else
-    REPLACE_MALLOC_FOR_MALLOC_POSIX=1
-  fi
+  case "$gl_cv_func_malloc_posix" in
+    *yes)
+      AC_DEFINE([HAVE_MALLOC_POSIX], [1],
+        [Define if malloc and calloc set errno on allocation failure.])
+      ;;
+    *)
+      REPLACE_MALLOC_FOR_MALLOC_POSIX=1
+      ;;
+  esac
 ])
 
-# Test whether malloc, realloc, calloc set errno to ENOMEM on failure.
-# Set gl_cv_func_malloc_posix to yes or no accordingly.
+# Test whether malloc, calloc set errno to ENOMEM on failure.
+# Set gl_cv_func_malloc_posix to *yes or *no accordingly.
 AC_DEFUN([gl_CHECK_MALLOC_POSIX],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
-  AC_CACHE_CHECK([whether malloc, realloc, calloc set errno on failure],
+  AC_CACHE_CHECK([whether malloc, calloc set errno on failure],
     [gl_cv_func_malloc_posix],
     [
       dnl It is too dangerous to try to allocate a large amount of memory:
       dnl some systems go to their knees when you do that. So assume that
       dnl all Unix implementations of the function set errno on failure,
       dnl except on those platforms where we have seen 'test-malloc-gnu',
-      dnl 'test-realloc-gnu', 'test-calloc-gnu' fail.
+      dnl 'test-realloc-posix', 'test-calloc-gnu' fail. For platforms
+      dnl where only 'test-realloc-posix', see realloc.m4.
       case "$host_os" in
-        mingw*)
-          gl_cv_func_malloc_posix=no ;;
+        mingw* | windows*)
+          dnl Old MSVCRT from 2001 did not set errno=ENOMEM when malloc failed.
+          dnl More recent MSVCRT from 2019 does so.
+          dnl UCRT is the successor of MSVCRT. Assume that UCRT does so as well.
+          AC_COMPILE_IFELSE(
+            [AC_LANG_PROGRAM(
+              [[#include <stdio.h>
+                #ifndef _UCRT
+                msvcrt yuck
+                #endif
+              ]],
+              [[]])
+            ],
+            [gl_cv_func_malloc_posix="guessing yes"],
+            [gl_cv_func_malloc_posix="guessing no"])
+          ;;
         irix* | solaris*)
           dnl On IRIX 6.5, the three functions return NULL with errno unset
           dnl when the argument is larger than PTRDIFF_MAX.
diff --git a/gl/m4/malloca.m4 b/gl/m4/malloca.m4
index 1d777ebe..cabe5fe7 100644
--- a/gl/m4/malloca.m4
+++ b/gl/m4/malloca.m4
@@ -1,14 +1,16 @@
-# malloca.m4 serial 2
-dnl Copyright (C) 2003-2004, 2006-2007, 2009-2023 Free Software Foundation,
+# malloca.m4
+# serial 3
+dnl Copyright (C) 2003-2004, 2006-2007, 2009-2025 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_MALLOCA],
 [
   dnl Use the autoconf tests for alloca(), but not the AC_SUBSTed variables
   dnl @ALLOCA@ and @LTALLOCA@.
   dnl gl_FUNC_ALLOCA   dnl Already brought in by the module dependencies.
-  AC_REQUIRE([gl_EEMALLOC])
+  AC_REQUIRE([gl_FUNC_MALLOC_GNU])
 ])
diff --git a/gl/m4/math_h.m4 b/gl/m4/math_h.m4
index d2e90ff1..8c27503b 100644
--- a/gl/m4/math_h.m4
+++ b/gl/m4/math_h.m4
@@ -1,8 +1,10 @@
-# math_h.m4 serial 125
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# math_h.m4
+# serial 140.1
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_MATH_H],
 [
@@ -42,15 +44,21 @@ AC_DEFUN_ONCE([gl_MATH_H],
      cbrt cbrtf cbrtl ceilf ceill copysign copysignf copysignl cosf cosl coshf
      expf expl exp2 exp2f exp2l expm1 expm1f expm1l
      fabsf fabsl floorf floorl fma fmaf fmal
-     fmod fmodf fmodl frexpf frexpl hypotf hypotl
+     fmod fmodf fmodl frexpf frexpl
+     getpayload getpayloadf getpayloadl
+     hypotf hypotl
      ilogb ilogbf ilogbl
      ldexpf ldexpl
      log logf logl log10 log10f log10l log1p log1pf log1pl log2 log2f log2l
-     logb logbf logbl
+     logb logbf logbl logp1 log1pf logp1l
      modf modff modfl powf
      remainder remainderf remainderl
-     rint rintf rintl round roundf roundl sinf sinl sinhf sqrtf sqrtl
-     tanf tanl tanhf trunc truncf truncl])
+     rint rintf rintl round roundf roundl
+     setpayload setpayloadf setpayloadl
+     setpayloadsig setpayloadsigf setpayloadsigl
+     sinf sinl sinhf sqrtf sqrtl
+     tanf tanl tanhf totalorder totalorderf totalorderl totalordermag
+     totalordermagf totalordermagl trunc truncf truncl])
 ])
 
 # gl_MATH_MODULE_INDICATOR([modulename])
@@ -113,6 +121,9 @@ AC_DEFUN([gl_MATH_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREXPF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREXP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREXPL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETPAYLOAD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETPAYLOADF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETPAYLOADL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_HYPOT])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_HYPOTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_HYPOTL])
@@ -125,6 +136,7 @@ AC_DEFUN([gl_MATH_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISNANF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISNAND])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISNANL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LDEXP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LDEXPF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LDEXPL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOG])
@@ -142,6 +154,9 @@ AC_DEFUN([gl_MATH_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGB])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGBF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGBL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGP1])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGP1F])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_LOGP1L])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MODF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MODFF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MODFL])
@@ -155,6 +170,12 @@ AC_DEFUN([gl_MATH_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ROUND])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ROUNDF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ROUNDL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETPAYLOAD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETPAYLOADF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETPAYLOADL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETPAYLOADSIG])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETPAYLOADSIGF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETPAYLOADSIGL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGNBIT])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SINF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SINL])
@@ -164,6 +185,12 @@ AC_DEFUN([gl_MATH_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TANF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TANL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TANHF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TOTALORDER])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TOTALORDERF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TOTALORDERL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TOTALORDERMAG])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TOTALORDERMAGF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TOTALORDERMAGL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TRUNC])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TRUNCF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TRUNCL])
@@ -209,6 +236,9 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   HAVE_FMODF=1;                     AC_SUBST([HAVE_FMODF])
   HAVE_FMODL=1;                     AC_SUBST([HAVE_FMODL])
   HAVE_FREXPF=1;                    AC_SUBST([HAVE_FREXPF])
+  HAVE_GETPAYLOAD=1;                AC_SUBST([HAVE_GETPAYLOAD])
+  HAVE_GETPAYLOADF=1;               AC_SUBST([HAVE_GETPAYLOADF])
+  HAVE_GETPAYLOADL=1;               AC_SUBST([HAVE_GETPAYLOADL])
   HAVE_HYPOTF=1;                    AC_SUBST([HAVE_HYPOTF])
   HAVE_HYPOTL=1;                    AC_SUBST([HAVE_HYPOTL])
   HAVE_ILOGB=1;                     AC_SUBST([HAVE_ILOGB])
@@ -227,6 +257,9 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   HAVE_LOG1PL=1;                    AC_SUBST([HAVE_LOG1PL])
   HAVE_LOGBF=1;                     AC_SUBST([HAVE_LOGBF])
   HAVE_LOGBL=1;                     AC_SUBST([HAVE_LOGBL])
+  HAVE_LOGP1=1;                     AC_SUBST([HAVE_LOGP1])
+  HAVE_LOGP1F=1;                    AC_SUBST([HAVE_LOGP1F])
+  HAVE_LOGP1L=1;                    AC_SUBST([HAVE_LOGP1L])
   HAVE_MODFF=1;                     AC_SUBST([HAVE_MODFF])
   HAVE_MODFL=1;                     AC_SUBST([HAVE_MODFL])
   HAVE_POWF=1;                      AC_SUBST([HAVE_POWF])
@@ -234,6 +267,12 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   HAVE_REMAINDERF=1;                AC_SUBST([HAVE_REMAINDERF])
   HAVE_RINT=1;                      AC_SUBST([HAVE_RINT])
   HAVE_RINTL=1;                     AC_SUBST([HAVE_RINTL])
+  HAVE_SETPAYLOAD=1;                AC_SUBST([HAVE_SETPAYLOAD])
+  HAVE_SETPAYLOADF=1;               AC_SUBST([HAVE_SETPAYLOADF])
+  HAVE_SETPAYLOADL=1;               AC_SUBST([HAVE_SETPAYLOADL])
+  HAVE_SETPAYLOADSIG=1;             AC_SUBST([HAVE_SETPAYLOADSIG])
+  HAVE_SETPAYLOADSIGF=1;            AC_SUBST([HAVE_SETPAYLOADSIGF])
+  HAVE_SETPAYLOADSIGL=1;            AC_SUBST([HAVE_SETPAYLOADSIGL])
   HAVE_SINF=1;                      AC_SUBST([HAVE_SINF])
   HAVE_SINL=1;                      AC_SUBST([HAVE_SINL])
   HAVE_SINHF=1;                     AC_SUBST([HAVE_SINHF])
@@ -242,6 +281,12 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   HAVE_TANF=1;                      AC_SUBST([HAVE_TANF])
   HAVE_TANL=1;                      AC_SUBST([HAVE_TANL])
   HAVE_TANHF=1;                     AC_SUBST([HAVE_TANHF])
+  HAVE_TOTALORDER=1;                AC_SUBST([HAVE_TOTALORDER])
+  HAVE_TOTALORDERF=1;               AC_SUBST([HAVE_TOTALORDERF])
+  HAVE_TOTALORDERL=1;               AC_SUBST([HAVE_TOTALORDERL])
+  HAVE_TOTALORDERMAG=1;             AC_SUBST([HAVE_TOTALORDERMAG])
+  HAVE_TOTALORDERMAGF=1;            AC_SUBST([HAVE_TOTALORDERMAGF])
+  HAVE_TOTALORDERMAGL=1;            AC_SUBST([HAVE_TOTALORDERMAGL])
   HAVE_DECL_ACOSL=1;                AC_SUBST([HAVE_DECL_ACOSL])
   HAVE_DECL_ASINL=1;                AC_SUBST([HAVE_DECL_ASINL])
   HAVE_DECL_ATANL=1;                AC_SUBST([HAVE_DECL_ATANL])
@@ -309,6 +354,9 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   REPLACE_FREXPF=0;                 AC_SUBST([REPLACE_FREXPF])
   REPLACE_FREXP=0;                  AC_SUBST([REPLACE_FREXP])
   REPLACE_FREXPL=0;                 AC_SUBST([REPLACE_FREXPL])
+  REPLACE_GETPAYLOAD=0;             AC_SUBST([REPLACE_GETPAYLOAD])
+  REPLACE_GETPAYLOADF=0;            AC_SUBST([REPLACE_GETPAYLOADF])
+  REPLACE_GETPAYLOADL=0;            AC_SUBST([REPLACE_GETPAYLOADL])
   REPLACE_HUGE_VAL=0;               AC_SUBST([REPLACE_HUGE_VAL])
   REPLACE_HYPOT=0;                  AC_SUBST([REPLACE_HYPOT])
   REPLACE_HYPOTF=0;                 AC_SUBST([REPLACE_HYPOTF])
@@ -319,6 +367,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   REPLACE_ISFINITE=0;               AC_SUBST([REPLACE_ISFINITE])
   REPLACE_ISINF=0;                  AC_SUBST([REPLACE_ISINF])
   REPLACE_ISNAN=0;                  AC_SUBST([REPLACE_ISNAN])
+  REPLACE_LDEXP=0;                  AC_SUBST([REPLACE_LDEXP])
   REPLACE_LDEXPL=0;                 AC_SUBST([REPLACE_LDEXPL])
   REPLACE_LOG=0;                    AC_SUBST([REPLACE_LOG])
   REPLACE_LOGF=0;                   AC_SUBST([REPLACE_LOGF])
@@ -350,10 +399,17 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   REPLACE_SIGNBIT_USING_BUILTINS=0; AC_SUBST([REPLACE_SIGNBIT_USING_BUILTINS])
   REPLACE_SINF=0;                   AC_SUBST([REPLACE_SINF])
   REPLACE_SINHF=0;                  AC_SUBST([REPLACE_SINHF])
+  REPLACE_SINL=0;                   AC_SUBST([REPLACE_SINL])
   REPLACE_SQRTF=0;                  AC_SUBST([REPLACE_SQRTF])
   REPLACE_SQRTL=0;                  AC_SUBST([REPLACE_SQRTL])
   REPLACE_TANF=0;                   AC_SUBST([REPLACE_TANF])
   REPLACE_TANHF=0;                  AC_SUBST([REPLACE_TANHF])
+  REPLACE_TOTALORDER=0;             AC_SUBST([REPLACE_TOTALORDER])
+  REPLACE_TOTALORDERF=0;            AC_SUBST([REPLACE_TOTALORDERF])
+  REPLACE_TOTALORDERL=0;            AC_SUBST([REPLACE_TOTALORDERL])
+  REPLACE_TOTALORDERMAG=0;          AC_SUBST([REPLACE_TOTALORDERMAG])
+  REPLACE_TOTALORDERMAGF=0;         AC_SUBST([REPLACE_TOTALORDERMAGF])
+  REPLACE_TOTALORDERMAGL=0;         AC_SUBST([REPLACE_TOTALORDERMAGL])
   REPLACE_TRUNC=0;                  AC_SUBST([REPLACE_TRUNC])
   REPLACE_TRUNCF=0;                 AC_SUBST([REPLACE_TRUNCF])
   REPLACE_TRUNCL=0;                 AC_SUBST([REPLACE_TRUNCL])
@@ -364,7 +420,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
 # Sets variable HAVE_SAME_LONG_DOUBLE_AS_DOUBLE to 0 or 1, and defines
 # HAVE_SAME_LONG_DOUBLE_AS_DOUBLE accordingly.
 # The currently known platforms where this is the case are:
-# Linux/HPPA, Minix 3.1.8, AIX 5, AIX 6 and 7 with xlc, MSVC 9.
+# Linux/HPPA, NetBSD/sparc32, Minix 3.1.8, AIX 5, AIX 6 and 7 with xlc, MSVC 9.
 AC_DEFUN([gl_LONG_DOUBLE_VS_DOUBLE],
 [
   AC_CACHE_CHECK([whether long double and double are the same],
diff --git a/gl/m4/mbchar.m4 b/gl/m4/mbchar.m4
new file mode 100644
index 00000000..b76f1d7b
--- /dev/null
+++ b/gl/m4/mbchar.m4
@@ -0,0 +1,15 @@
+# mbchar.m4
+# serial 9
+dnl Copyright (C) 2005-2007, 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl autoconf tests required for use of mbchar.m4
+dnl From Bruno Haible.
+
+AC_DEFUN([gl_MBCHAR],
+[
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+])
diff --git a/gl/m4/mbiter.m4 b/gl/m4/mbiter.m4
new file mode 100644
index 00000000..b51242e6
--- /dev/null
+++ b/gl/m4/mbiter.m4
@@ -0,0 +1,16 @@
+# mbiter.m4
+# serial 7
+dnl Copyright (C) 2005, 2008-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl autoconf tests required for use of mbiter.h
+dnl From Bruno Haible.
+
+AC_DEFUN([gl_MBITER],
+[
+  AC_REQUIRE([AC_TYPE_MBSTATE_T])
+  :
+])
diff --git a/gl/m4/mbrtoc32.m4 b/gl/m4/mbrtoc32.m4
new file mode 100644
index 00000000..1991529c
--- /dev/null
+++ b/gl/m4/mbrtoc32.m4
@@ -0,0 +1,326 @@
+# mbrtoc32.m4
+# serial 21
+dnl Copyright (C) 2014-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_MBRTOC32],
+[
+  AC_REQUIRE([gl_UCHAR_H_DEFAULTS])
+
+  AC_REQUIRE([AC_TYPE_MBSTATE_T])
+  dnl Determine REPLACE_MBSTATE_T, from which GNULIB_defined_mbstate_t is
+  dnl determined.  It describes how our overridden mbrtowc is implemented.
+  dnl We then implement mbrtoc32 accordingly.
+  AC_REQUIRE([gl_MBSTATE_T_BROKEN])
+
+  AC_REQUIRE([gl_TYPE_CHAR32_T])
+  AC_REQUIRE([gl_MBRTOC32_SANITYCHECK])
+
+  AC_REQUIRE([gl_CHECK_FUNC_MBRTOC32])
+  if test $gl_cv_func_mbrtoc32 = no; then
+    HAVE_MBRTOC32=0
+  else
+    if test $GNULIBHEADERS_OVERRIDE_CHAR32_T = 1 || test $REPLACE_MBSTATE_T = 1; then
+      REPLACE_MBRTOC32=1
+    else
+      gl_MBRTOC32_EMPTY_INPUT
+      gl_MBRTOC32_C_LOCALE
+      gl_MBRTOC32_UTF8_LOCALE
+      case "$gl_cv_func_mbrtoc32_empty_input" in
+        *yes) ;;
+        *) AC_DEFINE([MBRTOC32_EMPTY_INPUT_BUG], [1],
+             [Define if the mbrtoc32 function does not return (size_t) -2 for empty input.])
+           REPLACE_MBRTOC32=1
+           ;;
+      esac
+      case "$gl_cv_func_mbrtoc32_C_locale_sans_EILSEQ" in
+        *yes) ;;
+        *) AC_DEFINE([MBRTOC32_IN_C_LOCALE_MAYBE_EILSEQ], [1],
+             [Define if the mbrtoc32 function may signal encoding errors in the C locale.])
+           REPLACE_MBRTOC32=1
+           ;;
+      esac
+      case "$gl_cv_func_mbrtoc32_utf8_locale_works" in
+        *yes) ;;
+        *) AC_DEFINE([MBRTOC32_MULTIBYTE_LOCALE_BUG], [1],
+             [Define if the mbrtoc32 function does not accept the input bytes one-by-one.])
+           REPLACE_MBRTOC32=1
+           dnl Our replacement mbrtoc32 can handle UTF-8, but not GB18030.
+           LOCALE_ZH_CN=none
+           ;;
+      esac
+    fi
+    if test $HAVE_WORKING_MBRTOC32 = 0; then
+      REPLACE_MBRTOC32=1
+    fi
+  fi
+])
+
+AC_DEFUN([gl_CHECK_FUNC_MBRTOC32],
+[
+  dnl Cf. gl_CHECK_FUNCS_ANDROID
+  AC_CHECK_DECL([mbrtoc32], , ,
+    [[#ifdef __HAIKU__
+       #include <stdint.h>
+      #endif
+      #include <uchar.h>
+    ]])
+  if test $ac_cv_have_decl_mbrtoc32 = yes; then
+    dnl We can't use AC_CHECK_FUNC here, because mbrtoc32() is defined as a
+    dnl static inline function on Haiku 2020.
+    AC_CACHE_CHECK([for mbrtoc32], [gl_cv_func_mbrtoc32],
+      [AC_LINK_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <stdlib.h>
+              #ifdef __HAIKU__
+               #include <stdint.h>
+              #endif
+              #include <uchar.h>
+            ]],
+            [[char32_t c;
+              return mbrtoc32 (&c, "", 1, NULL) == 0;
+            ]])
+         ],
+         [gl_cv_func_mbrtoc32=yes],
+         [gl_cv_func_mbrtoc32=no])
+      ])
+  else
+    gl_cv_func_mbrtoc32=no
+  fi
+])
+
+dnl Test whether mbrtoc32 returns the correct value on empty input.
+
+AC_DEFUN([gl_MBRTOC32_EMPTY_INPUT],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether mbrtoc32 works on empty input],
+    [gl_cv_func_mbrtoc32_empty_input],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+           #ifdef __HAIKU__
+            #include <stdint.h>
+           #endif
+           #include <uchar.h>
+           static char32_t wc;
+           static mbstate_t mbs;
+           int
+           main (void)
+           {
+             return mbrtoc32 (&wc, "", 0, &mbs) != (size_t) -2;
+           }]])],
+        [gl_cv_func_mbrtoc32_empty_input=yes],
+        [gl_cv_func_mbrtoc32_empty_input=no],
+        [case "$host_os" in
+                              # Guess no on glibc systems.
+           *-gnu* | gnu*)     gl_cv_func_mbrtoc32_empty_input="guessing no" ;;
+                              # Guess no on Android.
+           linux*-android*)   gl_cv_func_mbrtoc32_empty_input="guessing no" ;;
+                              # Guess no on native Windows.
+           mingw* | windows*) gl_cv_func_mbrtoc32_empty_input="guessing no" ;;
+           *)                 gl_cv_func_mbrtoc32_empty_input="guessing yes" ;;
+         esac
+        ])
+    ])
+])
+
+dnl <https://pubs.opengroup.org/onlinepubs/9699919799/functions/mbrtowc.html>
+dnl POSIX:2018 says regarding mbrtowc: "In the POSIX locale an [EILSEQ] error
+dnl cannot occur since all byte values are valid characters."  It is reasonable
+dnl to expect mbrtoc32 to behave in the same way.
+
+AC_DEFUN([gl_MBRTOC32_C_LOCALE],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether the C locale is free of encoding errors],
+    [gl_cv_func_mbrtoc32_C_locale_sans_EILSEQ],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <limits.h>
+            #include <locale.h>
+            #ifdef __HAIKU__
+             #include <stdint.h>
+            #endif
+            #include <uchar.h>
+          ]], [[
+            int i;
+            char *locale = setlocale (LC_ALL, "C");
+            if (! locale)
+              return 2;
+            for (i = CHAR_MIN; i <= CHAR_MAX; i++)
+              {
+                char c = i;
+                char32_t wc;
+                mbstate_t mbs = { 0, };
+                size_t ss = mbrtoc32 (&wc, &c, 1, &mbs);
+                if (1 < ss)
+                  return 3;
+              }
+            return 0;
+          ]])],
+       [gl_cv_func_mbrtoc32_C_locale_sans_EILSEQ=yes],
+       [gl_cv_func_mbrtoc32_C_locale_sans_EILSEQ=no],
+       [case "$host_os" in
+                             # Guess yes on native Windows.
+          mingw* | windows*) gl_cv_func_mbrtoc32_C_locale_sans_EILSEQ="guessing yes" ;;
+          *)                 gl_cv_func_mbrtoc32_C_locale_sans_EILSEQ="$gl_cross_guess_normal" ;;
+        esac
+       ])
+    ])
+])
+
+dnl Test whether mbrtoc32 works when it's fed the bytes one-by-one in an UTF-8
+dnl locale.
+
+AC_DEFUN([gl_MBRTOC32_UTF8_LOCALE],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether mbrtoc32 works in an UTF-8 locale],
+    [gl_cv_func_mbrtoc32_utf8_locale_works],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <locale.h>
+            #ifdef __HAIKU__
+             #include <stdint.h>
+            #endif
+            #include <uchar.h>
+          ]], [[
+            char *locale = setlocale (LC_ALL, "en_US.UTF-8");
+            if (locale)
+              {
+                /* This test fails on Cygwin 3.5.3.  */
+                mbstate_t state = { 0, };
+                char32_t uc = 0xDEADBEEF;
+                /* \360\237\220\203 = U+0001F403 */
+                if (mbrtoc32 (&uc, "\360", 1, &state) != (size_t)-2)
+                  return 1;
+                if (mbrtoc32 (&uc, "\237", 1, &state) != (size_t)-2)
+                  return 2;
+                if (mbrtoc32 (&uc, "\220", 1, &state) != (size_t)-2)
+                  return 3;
+                if (mbrtoc32 (&uc, "\203", 1, &state) != 1)
+                  return 4;
+                if (uc != 0x0001F403)
+                  return 5;
+              }
+            return 0;
+          ]])],
+       [gl_cv_func_mbrtoc32_utf8_locale_works=yes],
+       [gl_cv_func_mbrtoc32_utf8_locale_works=no],
+       [case "$host_os" in
+                   # Guess no on Cygwin.
+          cygwin*) gl_cv_func_mbrtoc32_utf8_locale_works="guessing no" ;;
+          *)       gl_cv_func_mbrtoc32_utf8_locale_works="$gl_cross_guess_normal" ;;
+        esac
+       ])
+    ])
+])
+
+dnl Test whether mbrtoc32 works not worse than mbrtowc.
+dnl Result is HAVE_WORKING_MBRTOC32.
+
+AC_DEFUN([gl_MBRTOC32_SANITYCHECK],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([gl_TYPE_CHAR32_T])
+  AC_REQUIRE([gl_CHECK_FUNC_MBRTOC32])
+  AC_REQUIRE([gt_LOCALE_FR])
+  AC_REQUIRE([gt_LOCALE_ZH_CN])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  if test $GNULIBHEADERS_OVERRIDE_CHAR32_T = 1 || test $gl_cv_func_mbrtoc32 = no; then
+    HAVE_WORKING_MBRTOC32=0
+  else
+    AC_CACHE_CHECK([whether mbrtoc32 works as well as mbrtowc],
+      [gl_cv_func_mbrtoc32_sanitycheck],
+      [
+        dnl Initial guess, used when cross-compiling or when no suitable locale
+        dnl is present.
+changequote(,)dnl
+        case "$host_os" in
+          # Guess no on FreeBSD, Solaris, native Windows.
+          freebsd* | midnightbsd* | solaris* | mingw* | windows*)
+            gl_cv_func_mbrtoc32_sanitycheck="guessing no"
+            ;;
+          # Guess yes otherwise.
+          *)
+            gl_cv_func_mbrtoc32_sanitycheck="guessing yes"
+            ;;
+        esac
+changequote([,])dnl
+        if test $LOCALE_FR != none || test $LOCALE_ZH_CN != none; then
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#ifdef __HAIKU__
+ #include <stdint.h>
+#endif
+#include <uchar.h>
+int main ()
+{
+  int result = 0;
+  /* This fails on native Windows:
+     mbrtoc32 returns (size_t)-1.
+     mbrtowc returns 1 (correct).  */
+  if (strcmp ("$LOCALE_FR", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_FR") != NULL)
+    {
+      mbstate_t state;
+      wchar_t wc = (wchar_t) 0xBADFACE;
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, "\374", 1, &state) == 1)
+        {
+          char32_t c32 = (wchar_t) 0xBADFACE;
+          memset (&state, '\0', sizeof (mbstate_t));
+          if (mbrtoc32 (&c32, "\374", 1, &state) != 1)
+            result |= 1;
+        }
+    }
+  /* This fails on FreeBSD 13.0 and Solaris 11.4:
+     mbrtoc32 returns (size_t)-2 or (size_t)-1.
+     mbrtowc returns 4 (correct).  */
+  if (strcmp ("$LOCALE_ZH_CN", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_ZH_CN") != NULL)
+    {
+      mbstate_t state;
+      wchar_t wc = (wchar_t) 0xBADFACE;
+      memset (&state, '\0', sizeof (mbstate_t));
+      if (mbrtowc (&wc, "\224\071\375\067", 4, &state) == 4)
+        {
+          char32_t c32 = (wchar_t) 0xBADFACE;
+          memset (&state, '\0', sizeof (mbstate_t));
+          if (mbrtoc32 (&c32, "\224\071\375\067", 4, &state) != 4)
+            result |= 2;
+        }
+    }
+  return result;
+}]])],
+            [gl_cv_func_mbrtoc32_sanitycheck=yes],
+            [gl_cv_func_mbrtoc32_sanitycheck=no],
+            [:])
+        fi
+      ])
+    case "$gl_cv_func_mbrtoc32_sanitycheck" in
+      *yes)
+        HAVE_WORKING_MBRTOC32=1
+        AC_DEFINE([HAVE_WORKING_MBRTOC32], [1],
+          [Define if the mbrtoc32 function basically works.])
+        ;;
+      *) HAVE_WORKING_MBRTOC32=0 ;;
+    esac
+  fi
+  AC_SUBST([HAVE_WORKING_MBRTOC32])
+])
+
+# Prerequisites of lib/mbrtoc32.c and lib/lc-charset-dispatch.c.
+AC_DEFUN([gl_PREREQ_MBRTOC32], [
+  AC_REQUIRE([gl_C32RTOMB_SANITYCHECK])
+  :
+])
diff --git a/gl/m4/mbrtowc.m4 b/gl/m4/mbrtowc.m4
index bb393041..cc09a5fb 100644
--- a/gl/m4/mbrtowc.m4
+++ b/gl/m4/mbrtowc.m4
@@ -1,9 +1,11 @@
-# mbrtowc.m4 serial 38  -*- coding: utf-8 -*-
-dnl Copyright (C) 2001-2002, 2004-2005, 2008-2023 Free Software Foundation,
+# mbrtowc.m4
+# serial 46
+dnl Copyright (C) 2001-2002, 2004-2005, 2008-2025 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_MBRTOWC],
 [
@@ -91,20 +93,25 @@ AC_DEFUN([gl_FUNC_MBRTOWC],
   fi
   if test $REPLACE_MBSTATE_T = 1; then
     case "$host_os" in
-      mingw*) LIB_MBRTOWC= ;;
+      mingw* | windows*)
+        MBRTOWC_LIB=
+        ;;
       *)
         gl_WEAK_SYMBOLS
         case "$gl_cv_have_weak" in
-          *yes) LIB_MBRTOWC= ;;
-          *)    LIB_MBRTOWC="$LIBPTHREAD" ;;
+          *yes) MBRTOWC_LIB= ;;
+          *)    MBRTOWC_LIB="$LIBPTHREAD" ;;
         esac
         ;;
     esac
   else
-    LIB_MBRTOWC=
+    MBRTOWC_LIB=
   fi
-  dnl LIB_MBRTOWC is expected to be '-pthread' or '-lpthread' on AIX
+  dnl MBRTOWC_LIB is expected to be '-pthread' or '-lpthread' on AIX
   dnl with gcc or xlc, and empty otherwise.
+  AC_SUBST([MBRTOWC_LIB])
+  dnl For backward compatibility.
+  LIB_MBRTOWC="$MBRTOWC_LIB"
   AC_SUBST([LIB_MBRTOWC])
 ])
 
@@ -114,7 +121,7 @@ dnl Result is REPLACE_MBSTATE_T.
 dnl When this is set to 1, we replace both mbsinit() and mbrtowc(), in order to
 dnl avoid inconsistencies.
 
-AC_DEFUN([gl_MBSTATE_T_BROKEN],
+AC_DEFUN_ONCE([gl_MBSTATE_T_BROKEN],
 [
   AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST])
@@ -126,7 +133,7 @@ AC_DEFUN([gl_MBSTATE_T_BROKEN],
   dnl to override it, even if - like on MSVC - mbsinit() is only defined as
   dnl an inline function, not as a global function.
   if case "$host_os" in
-       mingw*) true ;;
+       mingw* | windows*) true ;;
        *) test $ac_cv_func_mbsinit = yes ;;
      esac \
     && test $ac_cv_func_mbrtowc = yes; then
@@ -154,7 +161,7 @@ AC_DEFUN([gl_MBRTOWC_INCOMPLETE_STATE],
 [
   AC_REQUIRE([AC_PROG_CC])
   AC_REQUIRE([gt_LOCALE_JA])
-  AC_REQUIRE([gt_LOCALE_FR_UTF8])
+  AC_REQUIRE([gt_LOCALE_EN_UTF8])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether mbrtowc handles incomplete characters],
     [gl_cv_func_mbrtowc_incomplete_state],
@@ -194,7 +201,7 @@ int main ()
           [gl_cv_func_mbrtowc_incomplete_state=no],
           [:])
       else
-        if test $LOCALE_FR_UTF8 != none; then
+        if test "$LOCALE_EN_UTF8" != none; then
           AC_RUN_IFELSE(
             [AC_LANG_SOURCE([[
 #include <locale.h>
@@ -202,7 +209,7 @@ int main ()
 #include <wchar.h>
 int main ()
 {
-  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+  if (setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
     {
       const char input[] = "B\303\274\303\237er"; /* "Büßer" */
       mbstate_t state;
@@ -282,7 +289,7 @@ dnl Result is gl_cv_func_mbrtowc_null_arg1.
 AC_DEFUN([gl_MBRTOWC_NULL_ARG1],
 [
   AC_REQUIRE([AC_PROG_CC])
-  AC_REQUIRE([gt_LOCALE_FR_UTF8])
+  AC_REQUIRE([gt_LOCALE_EN_UTF8])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether mbrtowc handles a NULL pwc argument],
     [gl_cv_func_mbrtowc_null_arg1],
@@ -297,7 +304,7 @@ changequote(,)dnl
         *)        gl_cv_func_mbrtowc_null_arg1="guessing yes" ;;
       esac
 changequote([,])dnl
-      if test $LOCALE_FR_UTF8 != none; then
+      if test "$LOCALE_EN_UTF8" != none; then
         AC_RUN_IFELSE(
           [AC_LANG_SOURCE([[
 #include <locale.h>
@@ -308,7 +315,7 @@ int main ()
 {
   int result = 0;
 
-  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+  if (setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
     {
       char input[] = "\303\237er";
       mbstate_t state;
@@ -345,7 +352,7 @@ dnl Result is gl_cv_func_mbrtowc_null_arg2.
 AC_DEFUN([gl_MBRTOWC_NULL_ARG2],
 [
   AC_REQUIRE([AC_PROG_CC])
-  AC_REQUIRE([gt_LOCALE_FR_UTF8])
+  AC_REQUIRE([gt_LOCALE_EN_UTF8])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether mbrtowc handles a NULL string argument],
     [gl_cv_func_mbrtowc_null_arg2],
@@ -360,7 +367,7 @@ changequote(,)dnl
         *)    gl_cv_func_mbrtowc_null_arg2="guessing yes" ;;
       esac
 changequote([,])dnl
-      if test $LOCALE_FR_UTF8 != none; then
+      if test "$LOCALE_EN_UTF8" != none; then
         AC_RUN_IFELSE(
           [AC_LANG_SOURCE([[
 #include <locale.h>
@@ -368,7 +375,7 @@ changequote([,])dnl
 #include <wchar.h>
 int main ()
 {
-  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+  if (setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
     {
       mbstate_t state;
       wchar_t wc;
@@ -398,7 +405,7 @@ dnl Result is gl_cv_func_mbrtowc_retval.
 AC_DEFUN([gl_MBRTOWC_RETVAL],
 [
   AC_REQUIRE([AC_PROG_CC])
-  AC_REQUIRE([gt_LOCALE_FR_UTF8])
+  AC_REQUIRE([gt_LOCALE_EN_UTF8])
   AC_REQUIRE([gt_LOCALE_JA])
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_CACHE_CHECK([whether mbrtowc has a correct return value],
@@ -408,14 +415,16 @@ AC_DEFUN([gl_MBRTOWC_RETVAL],
       dnl is present.
 changequote(,)dnl
       case "$host_os" in
-                                   # Guess no on HP-UX, Solaris, native Windows.
-        hpux* | solaris* | mingw*) gl_cv_func_mbrtowc_retval="guessing no" ;;
-                                   # Guess yes otherwise.
-        *)                         gl_cv_func_mbrtowc_retval="guessing yes" ;;
+          # Guess no on HP-UX, Solaris, native Windows.
+        hpux* | solaris* | mingw* | windows*)
+          gl_cv_func_mbrtowc_retval="guessing no" ;;
+          # Guess yes otherwise.
+        *)
+          gl_cv_func_mbrtowc_retval="guessing yes" ;;
       esac
 changequote([,])dnl
-      if test $LOCALE_FR_UTF8 != none || test $LOCALE_JA != none \
-         || { case "$host_os" in mingw*) true;; *) false;; esac; }; then
+      if test "$LOCALE_EN_UTF8" != none || test $LOCALE_JA != none \
+         || { case "$host_os" in mingw* | windows*) true;; *) false;; esac; }; then
         AC_RUN_IFELSE(
           [AC_LANG_SOURCE([[
 #include <locale.h>
@@ -426,7 +435,8 @@ int main ()
   int result = 0;
   int found_some_locale = 0;
   /* This fails on Solaris.  */
-  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+  if (strcmp ("$LOCALE_EN_UTF8", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
     {
       char input[] = "B\303\274\303\237er"; /* "Büßer" */
       mbstate_t state;
@@ -442,7 +452,8 @@ int main ()
       found_some_locale = 1;
     }
   /* This fails on HP-UX 11.11.  */
-  if (setlocale (LC_ALL, "$LOCALE_JA") != NULL)
+  if (strcmp ("$LOCALE_JA", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_JA") != NULL)
     {
       char input[] = "B\217\253\344\217\251\316er"; /* "Büßer" */
       mbstate_t state;
@@ -577,13 +588,13 @@ AC_DEFUN([gl_MBRTOWC_STORES_INCOMPLETE],
      dnl is present.
 changequote(,)dnl
      case "$host_os" in
-               # Guess yes on native Windows.
-       mingw*) gl_cv_func_mbrtowc_stores_incomplete="guessing yes" ;;
-       *)      gl_cv_func_mbrtowc_stores_incomplete="guessing no" ;;
+                          # Guess yes on native Windows.
+       mingw* | windows*) gl_cv_func_mbrtowc_stores_incomplete="guessing yes" ;;
+       *)                 gl_cv_func_mbrtowc_stores_incomplete="guessing no" ;;
      esac
 changequote([,])dnl
      case "$host_os" in
-       mingw*)
+       mingw* | windows*)
          AC_RUN_IFELSE(
            [AC_LANG_SOURCE([[
 #include <locale.h>
@@ -639,8 +650,8 @@ int main ()
            [:])
          ;;
        *)
-         AC_REQUIRE([gt_LOCALE_FR_UTF8])
-         if test $LOCALE_FR_UTF8 != none; then
+         AC_REQUIRE([gt_LOCALE_EN_UTF8])
+         if test "$LOCALE_EN_UTF8" != none; then
            AC_RUN_IFELSE(
              [AC_LANG_SOURCE([[
 #include <locale.h>
@@ -648,7 +659,7 @@ int main ()
 #include <wchar.h>
 int main ()
 {
-  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+  if (setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
     {
       wchar_t wc = (wchar_t) 0xBADFACE;
       mbstate_t state;
@@ -677,31 +688,28 @@ AC_DEFUN([gl_MBRTOWC_EMPTY_INPUT],
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether mbrtowc works on empty input],
     [gl_cv_func_mbrtowc_empty_input],
-    [
-      dnl Initial guess, used when cross-compiling or when no suitable locale
-      dnl is present.
-changequote(,)dnl
-      case "$host_os" in
-                              # Guess no on AIX and glibc systems.
-        aix* | *-gnu* | gnu*) gl_cv_func_mbrtowc_empty_input="guessing no" ;;
-                              # Guess yes on native Windows.
-        mingw*)               gl_cv_func_mbrtowc_empty_input="guessing yes" ;;
-        *)                    gl_cv_func_mbrtowc_empty_input="guessing yes" ;;
-      esac
-changequote([,])dnl
-      AC_RUN_IFELSE(
-        [AC_LANG_SOURCE([[
-           #include <wchar.h>
-           static wchar_t wc;
-           static mbstate_t mbs;
-           int
-           main (void)
-           {
-             return mbrtowc (&wc, "", 0, &mbs) != (size_t) -2;
-           }]])],
-        [gl_cv_func_mbrtowc_empty_input=yes],
-        [gl_cv_func_mbrtowc_empty_input=no],
-        [:])
+    [AC_RUN_IFELSE(
+       [AC_LANG_SOURCE([[
+          #include <wchar.h>
+          static wchar_t wc;
+          static mbstate_t mbs;
+          int
+          main (void)
+          {
+            return mbrtowc (&wc, "", 0, &mbs) != (size_t) -2;
+          }]])],
+       [gl_cv_func_mbrtowc_empty_input=yes],
+       [gl_cv_func_mbrtowc_empty_input=no],
+       [case "$host_os" in
+                                # Guess no on AIX and glibc systems.
+          aix* | *-gnu* | gnu*) gl_cv_func_mbrtowc_empty_input="guessing no" ;;
+                                # Guess no on Android.
+          linux*-android*)      gl_cv_func_mbrtowc_empty_input="guessing no" ;;
+                                # Guess no on native Windows.
+          mingw* | windows*)    gl_cv_func_mbrtowc_empty_input="guessing no" ;;
+          *)                    gl_cv_func_mbrtowc_empty_input="guessing yes" ;;
+        esac
+       ])
     ])
 ])
 
@@ -709,18 +717,17 @@ dnl Test whether mbrtowc reports encoding errors in the C locale.
 dnl Although POSIX was never intended to allow this, the GNU C Library
 dnl and other implementations do it.  See:
 dnl https://sourceware.org/bugzilla/show_bug.cgi?id=19932
+dnl POSIX has now clarified it:
+dnl <https://pubs.opengroup.org/onlinepubs/9699919799/functions/mbrtowc.html>
+dnl says: "In the POSIX locale an [EILSEQ] error cannot occur since all byte
+dnl values are valid characters."
 
 AC_DEFUN([gl_MBRTOWC_C_LOCALE],
 [
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether the C locale is free of encoding errors],
     [gl_cv_func_mbrtowc_C_locale_sans_EILSEQ],
-    [
-     dnl Initial guess, used when cross-compiling or when no suitable locale
-     dnl is present.
-     gl_cv_func_mbrtowc_C_locale_sans_EILSEQ="$gl_cross_guess_normal"
-
-     AC_RUN_IFELSE(
+    [AC_RUN_IFELSE(
        [AC_LANG_PROGRAM(
           [[#include <limits.h>
             #include <locale.h>
@@ -741,13 +748,14 @@ AC_DEFUN([gl_MBRTOWC_C_LOCALE],
               }
             return 0;
           ]])],
-      [gl_cv_func_mbrtowc_C_locale_sans_EILSEQ=yes],
-      [gl_cv_func_mbrtowc_C_locale_sans_EILSEQ=no],
-      [case "$host_os" in
-                 # Guess yes on native Windows.
-         mingw*) gl_cv_func_mbrtowc_C_locale_sans_EILSEQ="guessing yes" ;;
-       esac
-      ])
+       [gl_cv_func_mbrtowc_C_locale_sans_EILSEQ=yes],
+       [gl_cv_func_mbrtowc_C_locale_sans_EILSEQ=no],
+       [case "$host_os" in
+                             # Guess yes on native Windows.
+          mingw* | windows*) gl_cv_func_mbrtowc_C_locale_sans_EILSEQ="guessing yes" ;;
+          *)                 gl_cv_func_mbrtowc_C_locale_sans_EILSEQ="$gl_cross_guess_normal" ;;
+        esac
+       ])
     ])
 ])
 
diff --git a/gl/m4/mbsinit.m4 b/gl/m4/mbsinit.m4
index c388a8b9..69cfa574 100644
--- a/gl/m4/mbsinit.m4
+++ b/gl/m4/mbsinit.m4
@@ -1,8 +1,10 @@
-# mbsinit.m4 serial 9
-dnl Copyright (C) 2008, 2010-2023 Free Software Foundation, Inc.
+# mbsinit.m4
+# serial 10
+dnl Copyright (C) 2008, 2010-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_MBSINIT],
 [
@@ -32,7 +34,7 @@ AC_DEFUN([gl_FUNC_MBSINIT],
       dnl states produced by mbrtowc() for an incomplete multibyte character
       dnl in multibyte locales.
       case "$host_os" in
-        mingw*) REPLACE_MBSINIT=1 ;;
+        mingw* | windows*) REPLACE_MBSINIT=1 ;;
       esac
     fi
   fi
diff --git a/gl/m4/mbstate_t.m4 b/gl/m4/mbstate_t.m4
index dcd66b96..59df1e2e 100644
--- a/gl/m4/mbstate_t.m4
+++ b/gl/m4/mbstate_t.m4
@@ -1,8 +1,10 @@
-# mbstate_t.m4 serial 14
-dnl Copyright (C) 2000-2002, 2008-2023 Free Software Foundation, Inc.
+# mbstate_t.m4
+# serial 14
+dnl Copyright (C) 2000-2002, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # From Paul Eggert.
 
diff --git a/gl/m4/mbtowc.m4 b/gl/m4/mbtowc.m4
index 7823be0e..3e3f6ce0 100644
--- a/gl/m4/mbtowc.m4
+++ b/gl/m4/mbtowc.m4
@@ -1,16 +1,21 @@
-# mbtowc.m4 serial 3
-dnl Copyright (C) 2011-2023 Free Software Foundation, Inc.
+# mbtowc.m4
+# serial 5
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_MBTOWC],
 [
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
 
-  AC_CHECK_FUNCS([mbtowc])
+  gl_CHECK_FUNCS_ANDROID([mbtowc], [[#include <stdlib.h>]])
   if test $ac_cv_func_mbtowc = no; then
     HAVE_MBTOWC=0
+    case "$gl_cv_onwards_func_mbtowc" in
+      future*) REPLACE_MBTOWC=1 ;;
+    esac
   else
     if false; then
       REPLACE_MBTOWC=1
diff --git a/gl/m4/memchr.m4 b/gl/m4/memchr.m4
index 4f1aed01..1c2ecf1d 100644
--- a/gl/m4/memchr.m4
+++ b/gl/m4/memchr.m4
@@ -1,8 +1,10 @@
-# memchr.m4 serial 18
-dnl Copyright (C) 2002-2004, 2009-2023 Free Software Foundation, Inc.
+# memchr.m4
+# serial 20
+dnl Copyright (C) 2002-2004, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
 [
@@ -48,7 +50,7 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
   if (fd >= 0)
 # endif
     {
-      int pagesize = getpagesize ();
+      long int pagesize = sysconf (_SC_PAGESIZE);
       char *two_pages =
         (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE,
                        flags, fd, 0);
@@ -85,12 +87,12 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
        [gl_cv_func_memchr_works=yes],
        [gl_cv_func_memchr_works=no],
        [case "$host_os" in
-                           # Guess no on Android.
-          linux*-android*) gl_cv_func_memchr_works="guessing no" ;;
-                           # Guess yes on native Windows.
-          mingw*)          gl_cv_func_memchr_works="guessing yes" ;;
-                           # If we don't know, obey --enable-cross-guesses.
-          *)               gl_cv_func_memchr_works="$gl_cross_guess_normal" ;;
+                             # Guess no on Android.
+          linux*-android*)   gl_cv_func_memchr_works="guessing no" ;;
+                             # Guess yes on native Windows.
+          mingw* | windows*) gl_cv_func_memchr_works="guessing yes" ;;
+                             # If we don't know, obey --enable-cross-guesses.
+          *)                 gl_cv_func_memchr_works="$gl_cross_guess_normal" ;;
         esac
        ])
     ])
diff --git a/gl/m4/minmax.m4 b/gl/m4/minmax.m4
index fd09846f..69c8a89f 100644
--- a/gl/m4/minmax.m4
+++ b/gl/m4/minmax.m4
@@ -1,8 +1,10 @@
-# minmax.m4 serial 4
-dnl Copyright (C) 2005, 2009-2023 Free Software Foundation, Inc.
+# minmax.m4
+# serial 4
+dnl Copyright (C) 2005, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_PREREQ([2.53])
 
diff --git a/gl/m4/mktime.m4 b/gl/m4/mktime.m4
index e9d31f35..eca6c4d8 100644
--- a/gl/m4/mktime.m4
+++ b/gl/m4/mktime.m4
@@ -1,9 +1,11 @@
-# serial 37
-dnl Copyright (C) 2002-2003, 2005-2007, 2009-2023 Free Software Foundation,
+# mktime.m4
+# serial 42
+dnl Copyright (C) 2002-2003, 2005-2007, 2009-2025 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Jim Meyering.
 
@@ -264,9 +266,9 @@ main ()
          [gl_cv_func_working_mktime=yes],
          [gl_cv_func_working_mktime=no],
          [case "$host_os" in
-                    # Guess no on native Windows.
-            mingw*) gl_cv_func_working_mktime="guessing no" ;;
-            *)      gl_cv_func_working_mktime="$gl_cross_guess_normal" ;;
+                               # Guess no on native Windows.
+            mingw* | windows*) gl_cv_func_working_mktime="guessing no" ;;
+            *)                 gl_cv_func_working_mktime="$gl_cross_guess_normal" ;;
           esac
          ])
      fi
@@ -280,7 +282,6 @@ AC_DEFUN([gl_FUNC_MKTIME],
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([gl_FUNC_MKTIME_WORKS])
 
-  REPLACE_MKTIME=0
   if test "$gl_cv_func_working_mktime" != yes; then
     REPLACE_MKTIME=1
     AC_DEFINE([NEED_MKTIME_WORKING], [1],
@@ -288,7 +289,7 @@ AC_DEFUN([gl_FUNC_MKTIME],
        with the algorithmic workarounds.])
   fi
   case "$host_os" in
-    mingw*)
+    mingw* | windows*)
       REPLACE_MKTIME=1
       AC_DEFINE([NEED_MKTIME_WINDOWS], [1],
         [Define if the compilation of mktime.c should define 'mktime'
diff --git a/gl/m4/mmap-anon.m4 b/gl/m4/mmap-anon.m4
index d07d26e4..3f7a6656 100644
--- a/gl/m4/mmap-anon.m4
+++ b/gl/m4/mmap-anon.m4
@@ -1,8 +1,10 @@
-# mmap-anon.m4 serial 12
-dnl Copyright (C) 2005, 2007, 2009-2023 Free Software Foundation, Inc.
+# mmap-anon.m4
+# serial 12
+dnl Copyright (C) 2005, 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # Detect how mmap can be used to create anonymous (not file-backed) memory
 # mappings.
diff --git a/gl/m4/mode_t.m4 b/gl/m4/mode_t.m4
index 82197c02..7dae201b 100644
--- a/gl/m4/mode_t.m4
+++ b/gl/m4/mode_t.m4
@@ -1,8 +1,10 @@
-# mode_t.m4 serial 2
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# mode_t.m4
+# serial 2
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # For using mode_t, it's sufficient to use AC_TYPE_MODE_T and
 # include <sys/types.h>.
diff --git a/gl/m4/mountlist.m4 b/gl/m4/mountlist.m4
index a9b4edb9..e7eac2e9 100644
--- a/gl/m4/mountlist.m4
+++ b/gl/m4/mountlist.m4
@@ -1,8 +1,10 @@
-# serial 15
-dnl Copyright (C) 2002-2006, 2009-2023 Free Software Foundation, Inc.
+# mountlist.m4
+# serial 18
+dnl Copyright (C) 2002-2006, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Jim Meyering.
 
@@ -106,7 +108,18 @@ $ac_includes_default
           [Define if there is a function named getmntent for reading the list
            of mounted file systems, and that function takes a single argument.
            (4.3BSD, SunOS, HP-UX, Irix)])
-        AC_CHECK_FUNCS([setmntent endmntent hasmntopt])
+        gl_CHECK_FUNCS_ANDROID([setmntent],
+          [[#include <stdio.h>
+            #include <mntent.h>
+          ]])
+        gl_CHECK_FUNCS_ANDROID([endmntent],
+          [[#include <stdio.h>
+            #include <mntent.h>
+          ]])
+        gl_CHECK_FUNCS_ANDROID([hasmntopt],
+          [[#include <stdio.h>
+            #include <mntent.h>
+          ]])
       fi
     fi
 
@@ -306,12 +319,17 @@ int getmntinfo (struct statfs **, int);
   fi
 
   if test -z "$ac_list_mounted_fs"; then
-    AC_MSG_ERROR([could not determine how to read list of mounted file systems])
-    # FIXME -- no need to abort building the whole package
-    # Can't build mountlist.c or anything that needs its functions
+    case "$host_os" in
+      mingw* | windows*) ac_list_mounted_fs=found ;;
+    esac
+  fi
+
+  if test -z "$ac_list_mounted_fs"; then
+    AC_DEFINE([MOUNTED_NOT_PORTED], [1],
+      [Define if we don't know how to determine the list of mounted file systems.])
   fi
 
-  if test $ac_list_mounted_fs = found; then
+  if test "$ac_list_mounted_fs" = found; then
     gl_cv_list_mounted_fs=yes
   else
     gl_cv_list_mounted_fs=no
diff --git a/gl/m4/msvc-inval.m4 b/gl/m4/msvc-inval.m4
index 8d9d21b5..bfbb983b 100644
--- a/gl/m4/msvc-inval.m4
+++ b/gl/m4/msvc-inval.m4
@@ -1,8 +1,10 @@
-# msvc-inval.m4 serial 1
-dnl Copyright (C) 2011-2023 Free Software Foundation, Inc.
+# msvc-inval.m4
+# serial 1
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_MSVC_INVAL],
 [
diff --git a/gl/m4/msvc-nothrow.m4 b/gl/m4/msvc-nothrow.m4
index 0263e490..6a470971 100644
--- a/gl/m4/msvc-nothrow.m4
+++ b/gl/m4/msvc-nothrow.m4
@@ -1,8 +1,10 @@
-# msvc-nothrow.m4 serial 1
-dnl Copyright (C) 2011-2023 Free Software Foundation, Inc.
+# msvc-nothrow.m4
+# serial 1
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_MSVC_NOTHROW],
 [
diff --git a/gl/m4/multiarch.m4 b/gl/m4/multiarch.m4
index 3ba5b0f7..817f01f1 100644
--- a/gl/m4/multiarch.m4
+++ b/gl/m4/multiarch.m4
@@ -1,8 +1,10 @@
-# multiarch.m4 serial 9
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# multiarch.m4
+# serial 9
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # Determine whether the compiler is or may be producing universal binaries.
 #
diff --git a/gl/m4/musl.m4 b/gl/m4/musl.m4
new file mode 100644
index 00000000..6ff778cb
--- /dev/null
+++ b/gl/m4/musl.m4
@@ -0,0 +1,22 @@
+# musl.m4
+# serial 4
+dnl Copyright (C) 2019-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+# Test for musl libc, despite the musl libc authors don't like it
+# <https://wiki.musl-libc.org/faq.html>
+# <https://lists.gnu.org/archive/html/bug-gnulib/2018-02/msg00079.html>.
+# From Bruno Haible.
+
+AC_DEFUN_ONCE([gl_MUSL_LIBC],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    *-musl* | midipix*)
+      AC_DEFINE([MUSL_LIBC], [1], [Define to 1 on musl libc.])
+      ;;
+  esac
+])
diff --git a/gl/m4/netdb_h.m4 b/gl/m4/netdb_h.m4
index e6aa8925..88512546 100644
--- a/gl/m4/netdb_h.m4
+++ b/gl/m4/netdb_h.m4
@@ -1,8 +1,10 @@
-# netdb_h.m4 serial 15
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# netdb_h.m4
+# serial 15
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_NETDB_H],
 [
diff --git a/gl/m4/netinet_in_h.m4 b/gl/m4/netinet_in_h.m4
index 71154191..b56e354c 100644
--- a/gl/m4/netinet_in_h.m4
+++ b/gl/m4/netinet_in_h.m4
@@ -1,8 +1,10 @@
-# netinet_in_h.m4 serial 6
-dnl Copyright (C) 2006-2023 Free Software Foundation, Inc.
+# netinet_in_h.m4
+# serial 6
+dnl Copyright (C) 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_HEADER_NETINET_IN],
 [
diff --git a/gl/m4/nl_langinfo.m4 b/gl/m4/nl_langinfo.m4
index 51e783ce..9b1e0f32 100644
--- a/gl/m4/nl_langinfo.m4
+++ b/gl/m4/nl_langinfo.m4
@@ -1,14 +1,16 @@
-# nl_langinfo.m4 serial 8
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# nl_langinfo.m4
+# serial 12.1
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_NL_LANGINFO],
 [
   AC_REQUIRE([gl_LANGINFO_H_DEFAULTS])
   AC_REQUIRE([gl_LANGINFO_H])
-  AC_CHECK_FUNCS_ONCE([nl_langinfo])
+  gl_CHECK_FUNCS_ANDROID([nl_langinfo], [[#include <langinfo.h>]])
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([gl_FUNC_SETLOCALE_NULL])
   AC_REQUIRE([gl_PTHREADLIB])
@@ -39,16 +41,18 @@ AC_DEFUN([gl_FUNC_NL_LANGINFO],
     AC_DEFINE_UNQUOTED([FUNC_NL_LANGINFO_YESEXPR_WORKS],
       [$FUNC_NL_LANGINFO_YESEXPR_WORKS],
       [Define to 1 if nl_langinfo (YESEXPR) returns a non-empty string.])
-    # On Solaris 10 and Solaris 11.3, nl_langinfo is not multithread-safe.
+    # On macOS 26, Solaris 10, and Solaris 11.3, nl_langinfo is not
+    # multithread-safe.
     case "$host_os" in
-      solaris*) NL_LANGINFO_MTSAFE=0 ;;
-      *)        NL_LANGINFO_MTSAFE=1 ;;
+      darwin* | solaris*) NL_LANGINFO_MTSAFE=0 ;;
+      *)                  NL_LANGINFO_MTSAFE=1 ;;
     esac
     AC_DEFINE_UNQUOTED([NL_LANGINFO_MTSAFE], [$NL_LANGINFO_MTSAFE],
       [Define to 1 if nl_langinfo is multithread-safe.])
     if test $HAVE_LANGINFO_CODESET = 1 \
        && test $HAVE_LANGINFO_T_FMT_AMPM = 1 \
        && test $HAVE_LANGINFO_ALTMON = 1 \
+       && test $HAVE_LANGINFO_ABALTMON = 1 \
        && test $HAVE_LANGINFO_ERA = 1 \
        && test $FUNC_NL_LANGINFO_YESEXPR_WORKS = 1 \
        && test $NL_LANGINFO_MTSAFE = 1; then
@@ -60,9 +64,12 @@ AC_DEFUN([gl_FUNC_NL_LANGINFO],
     fi
   else
     HAVE_NL_LANGINFO=0
+    case "$gl_cv_onwards_func_nl_langinfo" in
+      future*) REPLACE_NL_LANGINFO=1 ;;
+    esac
   fi
   if test $HAVE_NL_LANGINFO = 0 || test $HAVE_LANGINFO_CODESET = 0; then
-    LIB_NL_LANGINFO="$LIB_SETLOCALE_NULL"
+    LIB_NL_LANGINFO="$SETLOCALE_NULL_LIB"
   else
     LIB_NL_LANGINFO=
   fi
diff --git a/gl/m4/nocrash.m4 b/gl/m4/nocrash.m4
index 6a766387..662fb049 100644
--- a/gl/m4/nocrash.m4
+++ b/gl/m4/nocrash.m4
@@ -1,8 +1,10 @@
-# nocrash.m4 serial 5
-dnl Copyright (C) 2005, 2009-2023 Free Software Foundation, Inc.
+# nocrash.m4
+# serial 5
+dnl Copyright (C) 2005, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Based on libsigsegv, from Bruno Haible and Paolo Bonzini.
 
diff --git a/gl/m4/off64_t.m4 b/gl/m4/off64_t.m4
new file mode 100644
index 00000000..963d53e9
--- /dev/null
+++ b/gl/m4/off64_t.m4
@@ -0,0 +1,32 @@
+# off64_t.m4
+# serial 1
+dnl Copyright (C) 2024-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl Check whether <sys/types.h> defines the 'off64_t' type.
+dnl Set HAVE_OFF64_T.
+
+AC_DEFUN([gl_TYPE_OFF64_T],
+[
+  dnl Persuade glibc <sys/types.h>, <stdio.h>, <fcntl.h>, <unistd.h>, <aio.h>
+  dnl to define off64_t.
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_CACHE_CHECK([for off64_t], [gl_cv_off64_t],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <sys/types.h>]],
+          [[int x = sizeof (off64_t *) + sizeof (off64_t);
+            return !x;]])],
+       [gl_cv_off64_t=yes], [gl_cv_off64_t=no])])
+
+  if test $gl_cv_off64_t != no; then
+    HAVE_OFF64_T=1
+  else
+    HAVE_OFF64_T=0
+  fi
+  AC_SUBST([HAVE_OFF64_T])
+])
diff --git a/gl/m4/off_t.m4 b/gl/m4/off_t.m4
index 880f3472..f4f4bbf6 100644
--- a/gl/m4/off_t.m4
+++ b/gl/m4/off_t.m4
@@ -1,8 +1,10 @@
-# off_t.m4 serial 1
-dnl Copyright (C) 2012-2023 Free Software Foundation, Inc.
+# off_t.m4
+# serial 1
+dnl Copyright (C) 2012-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Check whether to override the 'off_t' type.
 dnl Set WINDOWS_64_BIT_OFF_T.
diff --git a/gl/m4/once.m4 b/gl/m4/once.m4
new file mode 100644
index 00000000..7876a8fe
--- /dev/null
+++ b/gl/m4/once.m4
@@ -0,0 +1,14 @@
+# once.m4
+# serial 1
+dnl Copyright (C) 2024-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl From Bruno Haible.
+
+AC_DEFUN([gl_ONCE],
+[
+  AC_REQUIRE([gl_THREADLIB])
+])
diff --git a/gl/m4/open-cloexec.m4 b/gl/m4/open-cloexec.m4
index fd572fcd..860541b0 100644
--- a/gl/m4/open-cloexec.m4
+++ b/gl/m4/open-cloexec.m4
@@ -1,9 +1,12 @@
-# Test whether O_CLOEXEC is defined.
-
-dnl Copyright 2017-2023 Free Software Foundation, Inc.
+# open-cloexec.m4
+# serial 1
+dnl Copyright 2017-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+# Test whether O_CLOEXEC is defined.
 
 AC_DEFUN([gl_PREPROC_O_CLOEXEC],
 [
diff --git a/gl/m4/open-slash.m4 b/gl/m4/open-slash.m4
index 1f731f8a..2cba48fe 100644
--- a/gl/m4/open-slash.m4
+++ b/gl/m4/open-slash.m4
@@ -1,8 +1,10 @@
-# open-slash.m4 serial 2
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# open-slash.m4
+# serial 2
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Tests whether open() and creat() recognize a trailing slash.
 dnl Sets gl_cv_func_open_slash.
diff --git a/gl/m4/open.m4 b/gl/m4/open.m4
index 94fa2bb7..dd3a805f 100644
--- a/gl/m4/open.m4
+++ b/gl/m4/open.m4
@@ -1,15 +1,20 @@
-# open.m4 serial 15
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# open.m4
+# serial 17
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_OPEN],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([gl_PREPROC_O_CLOEXEC])
+  AC_REQUIRE([gl_FCNTL_O_FLAGS])
+  AS_CASE([$gl_cv_header_working_fcntl_h],
+    [*O_DIRECTORY* | *no], [REPLACE_OPEN=1])
   case "$host_os" in
-    mingw* | pw*)
+    mingw* | windows* | pw*)
       REPLACE_OPEN=1
       ;;
     *)
diff --git a/gl/m4/pathmax.m4 b/gl/m4/pathmax.m4
index 6d47d2c0..0c3925df 100644
--- a/gl/m4/pathmax.m4
+++ b/gl/m4/pathmax.m4
@@ -1,9 +1,11 @@
-# pathmax.m4 serial 11
-dnl Copyright (C) 2002-2003, 2005-2006, 2009-2023 Free Software Foundation,
+# pathmax.m4
+# serial 11
+dnl Copyright (C) 2002-2003, 2005-2006, 2009-2025 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_PATHMAX],
 [
diff --git a/gl/m4/pid_t.m4 b/gl/m4/pid_t.m4
index 0fd7d0a1..a8bdabc2 100644
--- a/gl/m4/pid_t.m4
+++ b/gl/m4/pid_t.m4
@@ -1,8 +1,10 @@
-# pid_t.m4 serial 4
-dnl Copyright (C) 2020-2023 Free Software Foundation, Inc.
+# pid_t.m4
+# serial 4
+dnl Copyright (C) 2020-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # The following implementation works around a problem in autoconf <= 2.69.
 m4_version_prereq([2.70], [], [
diff --git a/gl/m4/printf.m4 b/gl/m4/printf.m4
index 4e65abc6..4619a402 100644
--- a/gl/m4/printf.m4
+++ b/gl/m4/printf.m4
@@ -1,8 +1,10 @@
-# printf.m4 serial 73
-dnl Copyright (C) 2003, 2007-2023 Free Software Foundation, Inc.
+# printf.m4
+# serial 96
+dnl Copyright (C) 2003, 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Test whether the *printf family of functions supports the 'j', 'z', 't',
 dnl 'L' size specifiers. (ISO C99, POSIX:2001)
@@ -63,7 +65,7 @@ changequote(,)dnl
                                  # Guess yes on glibc systems.
            *-gnu* | gnu*)        gl_cv_func_printf_sizes_c99="guessing yes";;
                                  # Guess yes on musl systems.
-           *-musl*)              gl_cv_func_printf_sizes_c99="guessing yes";;
+           *-musl* | midipix*)   gl_cv_func_printf_sizes_c99="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_printf_sizes_c99="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_printf_sizes_c99="guessing yes";;
@@ -86,7 +88,8 @@ changequote(,)dnl
            linux*-android*)      gl_cv_func_printf_sizes_c99="guessing yes";;
 changequote([,])dnl
                                  # Guess yes on MSVC, no on mingw.
-           mingw*)               AC_EGREP_CPP([Known], [
+           windows*-msvc*)       gl_cv_func_printf_sizes_c99="guessing yes" ;;
+           mingw* | windows*)    AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
@@ -101,6 +104,92 @@ changequote([,])dnl
     ])
 ])
 
+dnl Test whether the *printf family of functions supports the 'w8', 'w16',
+dnl 'w32', 'w64', 'wf8', 'wf16', 'wf32', 'wf64' size specifiers. (ISO C23)
+dnl Result is gl_cv_func_printf_sizes_c23.
+
+AC_DEFUN([gl_PRINTF_SIZES_C23],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([gl_AC_HEADER_STDINT_H])
+  AC_REQUIRE([gl_AC_HEADER_INTTYPES_H])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports size specifiers as in C23],
+    [gl_cv_func_printf_sizes_c23],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#if HAVE_STDINT_H_WITH_UINTMAX
+# include <stdint.h>
+#endif
+#if HAVE_INTTYPES_H_WITH_UINTMAX
+# include <inttypes.h>
+#endif
+static char buf[100];
+int main ()
+{
+  int result = 0;
+  buf[0] = '\0';
+  if (sprintf (buf, "%w8u %d", (uint8_t) 123, 33, 44, 55) < 0
+      || strcmp (buf, "123 33") != 0)
+    result |= 1;
+  buf[0] = '\0';
+  if (sprintf (buf, "%wf8u %d", (uint_fast8_t) 123, 33, 44, 55) < 0
+      || strcmp (buf, "123 33") != 0)
+    result |= 1;
+  buf[0] = '\0';
+  if (sprintf (buf, "%w16u %d", (uint16_t) 12345, 33, 44, 55) < 0
+      || strcmp (buf, "12345 33") != 0)
+    result |= 2;
+  buf[0] = '\0';
+  if (sprintf (buf, "%wf16u %d", (uint_fast16_t) 12345, 33, 44, 55) < 0
+      || strcmp (buf, "12345 33") != 0)
+    result |= 2;
+  buf[0] = '\0';
+  if (sprintf (buf, "%w32u %d", (uint32_t) 12345671, 33, 44, 55) < 0
+      || strcmp (buf, "12345671 33") != 0)
+    result |= 4;
+  buf[0] = '\0';
+  if (sprintf (buf, "%wf32u %d", (uint_fast32_t) 12345671, 33, 44, 55) < 0
+      || strcmp (buf, "12345671 33") != 0)
+    result |= 4;
+#if HAVE_STDINT_H_WITH_UINTMAX || HAVE_INTTYPES_H_WITH_UINTMAX
+  buf[0] = '\0';
+  if (sprintf (buf, "%w64u %d", (uint64_t) 12345671, 33, 44, 55) < 0
+      || strcmp (buf, "12345671 33") != 0)
+    result |= 8;
+  buf[0] = '\0';
+  if (sprintf (buf, "%wf64u %d", (uint_fast64_t) 12345671, 33, 44, 55) < 0
+      || strcmp (buf, "12345671 33") != 0)
+    result |= 8;
+#else
+  result |= 8;
+#endif
+  return result;
+}]])],
+        [gl_cv_func_printf_sizes_c23=yes],
+        [gl_cv_func_printf_sizes_c23=no],
+        [
+         case "$host_os" in
+                               # Guess no on glibc systems.
+           *-gnu* | gnu*)      gl_cv_func_printf_sizes_c23="guessing no";;
+                               # Guess no on musl systems.
+           *-musl* | midipix*) gl_cv_func_printf_sizes_c23="guessing no";;
+                               # Guess no on Android.
+           linux*-android*)    gl_cv_func_printf_sizes_c23="guessing no";;
+                               # Guess no on native Windows.
+           mingw* | windows*)  gl_cv_func_printf_sizes_c23="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_printf_sizes_c23="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
 dnl Test whether the *printf family of functions supports 'long double'
 dnl arguments together with the 'L' size specifier. (ISO C99, POSIX:2001)
 dnl Result is gl_cv_func_printf_long_double.
@@ -137,20 +226,21 @@ int main ()
         [gl_cv_func_printf_long_double=yes],
         [gl_cv_func_printf_long_double=no],
         [case "$host_os" in
-                            # Guess no on BeOS.
-           beos*)           gl_cv_func_printf_long_double="guessing no";;
-                            # Guess yes on Android.
-           linux*-android*) gl_cv_func_printf_long_double="guessing yes";;
-                            # Guess yes on MSVC, no on mingw.
-           mingw*)          AC_EGREP_CPP([Known], [
+                              # Guess no on BeOS.
+           beos*)             gl_cv_func_printf_long_double="guessing no";;
+                              # Guess yes on Android.
+           linux*-android*)   gl_cv_func_printf_long_double="guessing yes";;
+                              # Guess yes on MSVC, no on mingw.
+           windows*-msvc*)    gl_cv_func_printf_long_double="guessing yes" ;;
+           mingw* | windows*) AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
-                              ],
-                              [gl_cv_func_printf_long_double="guessing yes"],
-                              [gl_cv_func_printf_long_double="guessing no"])
-                            ;;
-           *)               gl_cv_func_printf_long_double="guessing yes";;
+                                ],
+                                [gl_cv_func_printf_long_double="guessing yes"],
+                                [gl_cv_func_printf_long_double="guessing no"])
+                              ;;
+           *)                 gl_cv_func_printf_long_double="guessing yes";;
          esac
         ])
     ])
@@ -244,7 +334,7 @@ changequote(,)dnl
                                  # Guess yes on glibc systems.
            *-gnu* | gnu*)        gl_cv_func_printf_infinite="guessing yes";;
                                  # Guess yes on musl systems.
-           *-musl*)              gl_cv_func_printf_infinite="guessing yes";;
+           *-musl* | midipix*)   gl_cv_func_printf_infinite="guessing yes";;
                                  # Guess yes on FreeBSD >= 6.
            freebsd[1-5].*)       gl_cv_func_printf_infinite="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_printf_infinite="guessing yes";;
@@ -268,7 +358,8 @@ changequote(,)dnl
            linux*-android*)      gl_cv_func_printf_infinite="guessing no";;
 changequote([,])dnl
                                  # Guess yes on MSVC, no on mingw.
-           mingw*)               AC_EGREP_CPP([Known], [
+           windows*-msvc*)       gl_cv_func_printf_infinite="guessing yes" ;;
+           mingw* | windows*)    AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
@@ -467,7 +558,7 @@ changequote(,)dnl
                                          # Guess yes on glibc systems.
                    *-gnu* | gnu*)        gl_cv_func_printf_infinite_long_double="guessing yes";;
                                          # Guess yes on musl systems.
-                   *-musl*)              gl_cv_func_printf_infinite_long_double="guessing yes";;
+                   *-musl* | midipix*)   gl_cv_func_printf_infinite_long_double="guessing yes";;
                                          # Guess yes on FreeBSD >= 6.
                    freebsd[1-5].*)       gl_cv_func_printf_infinite_long_double="guessing no";;
                    freebsd* | kfreebsd*) gl_cv_func_printf_infinite_long_double="guessing yes";;
@@ -482,7 +573,8 @@ changequote(,)dnl
                    linux*-android*)      gl_cv_func_printf_infinite_long_double="guessing no";;
 changequote([,])dnl
                                          # Guess yes on MSVC, no on mingw.
-                   mingw*)               AC_EGREP_CPP([Known], [
+                   windows*-msvc*)       gl_cv_func_printf_infinite_long_double="guessing yes" ;;
+                   mingw* | windows*)    AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
@@ -525,6 +617,7 @@ static double zero = 0.0;
 int main ()
 {
   int result = 0;
+  /* This fails on FreeBSD 5.2.1, Solaris 11.4.  */
   if (sprintf (buf, "%a %d", 3.1416015625, 33, 44, 55) < 0
       || (strcmp (buf, "0x1.922p+1 33") != 0
           && strcmp (buf, "0x3.244p+0 33") != 0
@@ -536,27 +629,29 @@ int main ()
           && strcmp (buf, "-0X3.244P+0 33") != 0
           && strcmp (buf, "-0X6.488P-1 33") != 0
           && strcmp (buf, "-0XC.91P-2 33") != 0))
-    result |= 2;
-  /* This catches a FreeBSD 13.0 bug: it doesn't round.  */
+    result |= 1;
+  /* This catches a Mac OS X 10.5, FreeBSD 6.4, NetBSD 10.0 bug:
+     it doesn't round.  */
   if (sprintf (buf, "%.2a %d", 1.51, 33, 44, 55) < 0
       || (strcmp (buf, "0x1.83p+0 33") != 0
           && strcmp (buf, "0x3.05p-1 33") != 0
           && strcmp (buf, "0x6.0ap-2 33") != 0
           && strcmp (buf, "0xc.14p-3 33") != 0))
-    result |= 4;
-  /* This catches a Mac OS X 10.12.4 (Darwin 16.5) bug: it doesn't round.  */
+    result |= 2;
+  /* This catches a macOS 14 (Darwin 23), FreeBSD 14.0, OpenBSD 7.5, AIX 7.3,
+     Solaris 11.4 bug: it doesn't round.  */
   if (sprintf (buf, "%.0a %d", 1.51, 33, 44, 55) < 0
       || (strcmp (buf, "0x2p+0 33") != 0
           && strcmp (buf, "0x3p-1 33") != 0
           && strcmp (buf, "0x6p-2 33") != 0
           && strcmp (buf, "0xcp-3 33") != 0))
     result |= 4;
-  /* This catches a FreeBSD 6.1 bug.  See
+  /* This catches a Mac OS X 10.5, FreeBSD 6.4 bug.  See
      <https://lists.gnu.org/r/bug-gnulib/2007-04/msg00107.html> */
   if (sprintf (buf, "%010a %d", 1.0 / zero, 33, 44, 55) < 0
       || buf[0] == '0')
     result |= 8;
-  /* This catches a Mac OS X 10.3.9 (Darwin 7.9) bug.  */
+  /* This catches a Mac OS X 10.3.9 (Darwin 7.9), FreeBSD 6.4 bug.  */
   if (sprintf (buf, "%.1a", 1.999) < 0
       || (strcmp (buf, "0x1.0p+1") != 0
           && strcmp (buf, "0x2.0p+0") != 0
@@ -564,7 +659,8 @@ int main ()
           && strcmp (buf, "0x8.0p-2") != 0))
     result |= 16;
   /* This catches the same Mac OS X 10.3.9 (Darwin 7.9) bug and also a
-     glibc 2.4 bug <https://sourceware.org/bugzilla/show_bug.cgi?id=2908>.  */
+     glibc 2.4 bug <https://sourceware.org/bugzilla/show_bug.cgi?id=2908>
+     and a FreeBSD 6.4, NetBSD 10.0 bug.  */
   if (sprintf (buf, "%.1La", 1.999L) < 0
       || (strcmp (buf, "0x1.0p+1") != 0
           && strcmp (buf, "0x2.0p+0") != 0
@@ -591,11 +687,11 @@ int main ()
                [gl_cv_func_printf_directive_a="guessing no"])
              ;;
                                  # Guess yes on musl systems.
-           *-musl*)              gl_cv_func_printf_directive_a="guessing yes";;
+           *-musl* | midipix*)   gl_cv_func_printf_directive_a="guessing yes";;
                                  # Guess no on Android.
            linux*-android*)      gl_cv_func_printf_directive_a="guessing no";;
                                  # Guess no on native Windows.
-           mingw*)               gl_cv_func_printf_directive_a="guessing no";;
+           mingw* | windows*)    gl_cv_func_printf_directive_a="guessing no";;
                                  # If we don't know, obey --enable-cross-guesses.
            *)                    gl_cv_func_printf_directive_a="$gl_cross_guess_normal";;
          esac
@@ -603,6 +699,116 @@ int main ()
     ])
 ])
 
+dnl Test whether the *printf family of functions supports the 'b' conversion
+dnl specifier for binary output of integers.
+dnl (ISO C23)
+dnl Result is gl_cv_func_printf_directive_b.
+
+AC_DEFUN([gl_PRINTF_DIRECTIVE_B],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports the 'b' directive],
+    [gl_cv_func_printf_directive_b],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <string.h>
+static char buf[100];
+int main ()
+{
+  int result = 0;
+  if (sprintf (buf, "%b %d", 12345, 33, 44, 55) < 0
+      || strcmp (buf, "11000000111001 33") != 0)
+    result |= 1;
+  return result;
+}]])],
+        [gl_cv_func_printf_directive_b=yes],
+        [gl_cv_func_printf_directive_b=no],
+        [
+         case "$host_os" in
+                               # Guess yes on glibc >= 2.35 systems.
+           *-gnu* | gnu*)
+             AC_EGREP_CPP([Lucky], [
+               #include <features.h>
+               #ifdef __GNU_LIBRARY__
+                #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 35) || (__GLIBC__ > 2)
+                 Lucky user
+                #endif
+               #endif
+               ],
+               [gl_cv_func_printf_directive_uppercase_b="guessing yes"],
+               [gl_cv_func_printf_directive_uppercase_b="guessing no"])
+             ;;
+                               # Guess no on musl systems.
+           *-musl* | midipix*) gl_cv_func_printf_directive_b="guessing no";;
+                               # Guess no on Android.
+           linux*-android*)    gl_cv_func_printf_directive_b="guessing no";;
+                               # Guess no on native Windows.
+           mingw* | windows*)  gl_cv_func_printf_directive_b="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_printf_directive_b="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
+dnl Test whether the *printf family of functions supports the 'B' conversion
+dnl specifier for binary output of integers.
+dnl (GNU, encouraged by ISO C23 § 7.23.6.1)
+dnl Result is gl_cv_func_printf_directive_uppercase_b.
+
+AC_DEFUN([gl_PRINTF_DIRECTIVE_UPPERCASE_B],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports the 'B' directive],
+    [gl_cv_func_printf_directive_uppercase_b],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <string.h>
+static char buf[100];
+int main ()
+{
+  int result = 0;
+  if (sprintf (buf, "%#B %d", 12345, 33, 44, 55) < 0
+      || strcmp (buf, "0B11000000111001 33") != 0)
+    result |= 1;
+  return result;
+}]])],
+        [gl_cv_func_printf_directive_uppercase_b=yes],
+        [gl_cv_func_printf_directive_uppercase_b=no],
+        [
+         case "$host_os" in
+                               # Guess yes on glibc >= 2.35 systems.
+           *-gnu* | gnu*)
+             AC_EGREP_CPP([Lucky], [
+               #include <features.h>
+               #ifdef __GNU_LIBRARY__
+                #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 35) || (__GLIBC__ > 2)
+                 Lucky user
+                #endif
+               #endif
+               ],
+               [gl_cv_func_printf_directive_uppercase_b="guessing yes"],
+               [gl_cv_func_printf_directive_uppercase_b="guessing no"])
+             ;;
+                               # Guess no on musl systems.
+           *-musl* | midipix*) gl_cv_func_printf_directive_uppercase_b="guessing no";;
+                               # Guess no on Android.
+           linux*-android*)    gl_cv_func_printf_directive_uppercase_b="guessing no";;
+                               # Guess no on native Windows.
+           mingw* | windows*)  gl_cv_func_printf_directive_uppercase_b="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_printf_directive_uppercase_b="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
 dnl Test whether the *printf family of functions supports the %F format
 dnl directive. (ISO C99, POSIX:2001)
 dnl Result is gl_cv_func_printf_directive_f.
@@ -643,7 +849,7 @@ changequote(,)dnl
                                  # Guess yes on glibc systems.
            *-gnu* | gnu*)        gl_cv_func_printf_directive_f="guessing yes";;
                                  # Guess yes on musl systems.
-           *-musl*)              gl_cv_func_printf_directive_f="guessing yes";;
+           *-musl* | midipix*)   gl_cv_func_printf_directive_f="guessing yes";;
                                  # Guess yes on FreeBSD >= 6.
            freebsd[1-5].*)       gl_cv_func_printf_directive_f="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_printf_directive_f="guessing yes";;
@@ -661,7 +867,8 @@ changequote(,)dnl
            linux*-android*)      gl_cv_func_printf_directive_f="guessing no";;
 changequote([,])dnl
                                  # Guess yes on MSVC, no on mingw.
-           mingw*)               AC_EGREP_CPP([Known], [
+           windows*-msvc*)       gl_cv_func_printf_directive_f="guessing yes" ;;
+           mingw* | windows*)    AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
@@ -689,10 +896,16 @@ AC_DEFUN([gl_PRINTF_DIRECTIVE_N],
     [
       AC_RUN_IFELSE(
         [AC_LANG_SOURCE([[
+#include <signal.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
+#if defined _WIN32 && !defined __CYGWIN__
+# include <stdlib.h>
+#else
+# include <unistd.h>
+#endif
 #ifdef _MSC_VER
+#include <crtdbg.h>
 #include <inttypes.h>
 /* See page about "Parameter Validation" on msdn.microsoft.com.
    <https://docs.microsoft.com/en-us/cpp/c-runtime-library/parameter-validation>
@@ -706,6 +919,12 @@ invalid_parameter_handler (const wchar_t *expression,
   exit (1);
 }
 #endif
+static void
+abort_handler (int sig)
+{
+  (void) sig;
+  _exit (1);
+}
 static char fmtstring[10];
 static char buf[100];
 int main ()
@@ -713,7 +932,11 @@ int main ()
   int count = -1;
 #ifdef _MSC_VER
   _set_invalid_parameter_handler (invalid_parameter_handler);
+  /* Also avoid an Abort/Retry/Ignore dialog in debug builds.
+     <https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/crtsetreportmode>  */
+  _CrtSetReportMode (_CRT_ASSERT, 0);
 #endif
+  signal (SIGABRT, abort_handler);
   /* Copy the format string.  Some systems (glibc with _FORTIFY_SOURCE=2)
      support %n in format strings in read-only memory but not in writable
      memory.  */
@@ -727,21 +950,21 @@ int main ()
         [gl_cv_func_printf_directive_n=yes],
         [gl_cv_func_printf_directive_n=no],
         [case "$host_os" in
-                            # Guess no on glibc when _FORTIFY_SOURCE >= 2.
-           *-gnu* | gnu*)   AC_COMPILE_IFELSE(
-                              [AC_LANG_SOURCE(
-                                 [[#if _FORTIFY_SOURCE >= 2
-                                    error fail
-                                   #endif
-                                 ]])],
-                              [gl_cv_func_printf_directive_n="guessing yes"],
-                              [gl_cv_func_printf_directive_n="guessing no"])
-                            ;;
-                            # Guess no on Android.
-           linux*-android*) gl_cv_func_printf_directive_n="guessing no";;
-                            # Guess no on native Windows.
-           mingw*)          gl_cv_func_printf_directive_n="guessing no";;
-           *)               gl_cv_func_printf_directive_n="guessing yes";;
+                              # Guess no on glibc when _FORTIFY_SOURCE >= 2.
+           *-gnu* | gnu*)     AC_COMPILE_IFELSE(
+                                [AC_LANG_SOURCE(
+                                   [[#if _FORTIFY_SOURCE >= 2
+                                      error fail
+                                     #endif
+                                   ]])],
+                                [gl_cv_func_printf_directive_n="guessing yes"],
+                                [gl_cv_func_printf_directive_n="guessing no"])
+                              ;;
+                              # Guess no on Android.
+           linux*-android*)   gl_cv_func_printf_directive_n="guessing no";;
+                              # Guess no on native Windows.
+           mingw* | windows*) gl_cv_func_printf_directive_n="guessing no";;
+           *)                 gl_cv_func_printf_directive_n="guessing yes";;
          esac
         ])
     ])
@@ -811,18 +1034,64 @@ int main ()
         [
 changequote(,)dnl
          case "$host_os" in
-                            # Guess yes on OpenBSD >= 6.0.
-           openbsd[1-5].*)  gl_cv_func_printf_directive_ls="guessing no";;
-           openbsd*)        gl_cv_func_printf_directive_ls="guessing yes";;
-           irix*)           gl_cv_func_printf_directive_ls="guessing no";;
-           solaris*)        gl_cv_func_printf_directive_ls="guessing no";;
-           cygwin*)         gl_cv_func_printf_directive_ls="guessing no";;
-           beos* | haiku*)  gl_cv_func_printf_directive_ls="guessing no";;
-                            # Guess no on Android.
-           linux*-android*) gl_cv_func_printf_directive_ls="guessing no";;
-                            # Guess yes on native Windows.
-           mingw*)          gl_cv_func_printf_directive_ls="guessing yes";;
-           *)               gl_cv_func_printf_directive_ls="guessing yes";;
+                              # Guess yes on OpenBSD >= 6.0.
+           openbsd[1-5].*)    gl_cv_func_printf_directive_ls="guessing no";;
+           openbsd*)          gl_cv_func_printf_directive_ls="guessing yes";;
+           irix*)             gl_cv_func_printf_directive_ls="guessing no";;
+           solaris*)          gl_cv_func_printf_directive_ls="guessing no";;
+           cygwin*)           gl_cv_func_printf_directive_ls="guessing no";;
+           beos* | haiku*)    gl_cv_func_printf_directive_ls="guessing no";;
+                              # Guess no on Android.
+           linux*-android*)   gl_cv_func_printf_directive_ls="guessing no";;
+                              # Guess yes on native Windows.
+           mingw* | windows*) gl_cv_func_printf_directive_ls="guessing yes";;
+           *)                 gl_cv_func_printf_directive_ls="guessing yes";;
+         esac
+changequote([,])dnl
+        ])
+    ])
+])
+
+dnl Test whether the *printf family of functions supports the %lc format
+dnl directive and in particular, when the argument is a null wide character,
+dnl whether the functions produce a NUL byte, as specified in ISO C 23
+dnl after the issue GB-141 was fixed.
+dnl Result is gl_cv_func_printf_directive_lc.
+
+AC_DEFUN([gl_PRINTF_DIRECTIVE_LC],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports the 'lc' directive correctly],
+    [gl_cv_func_printf_directive_lc],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <wchar.h>
+#include <string.h>
+int main ()
+{
+  int result = 0;
+  char buf[100];
+  /* This test fails on musl libc 1.2.4.  */
+  {
+    buf[0] = '\0';
+    if (sprintf (buf, "%lc%lc%lc", (wint_t) 'a', (wint_t) 0, (wint_t) 'z') < 0
+        || memcmp (buf, "a\0z", 4) != 0)
+      result |= 1;
+  }
+  return result;
+}]])],
+        [gl_cv_func_printf_directive_lc=yes],
+        [gl_cv_func_printf_directive_lc=no],
+        [
+changequote(,)dnl
+         case "$host_os" in
+                               # Guess no on musl libc.
+           *-musl* | midipix*) gl_cv_func_printf_directive_lc="guessing no";;
+                               # Guess yes otherwise.
+           *)                  gl_cv_func_printf_directive_lc="guessing yes";;
          esac
 changequote([,])dnl
         ])
@@ -833,7 +1102,7 @@ dnl Test whether the *printf family of functions supports POSIX/XSI format
 dnl strings with positions. (POSIX:2001)
 dnl Result is gl_cv_func_printf_positions.
 
-AC_DEFUN([gl_PRINTF_POSITIONS],
+AC_DEFUN_ONCE([gl_PRINTF_POSITIONS],
 [
   AC_REQUIRE([AC_PROG_CC])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
@@ -859,13 +1128,17 @@ int main ()
 changequote(,)dnl
          case "$host_os" in
            netbsd[1-3]* | netbsdelf[1-3]* | netbsdaout[1-3]* | netbsdcoff[1-3]*)
-                            gl_cv_func_printf_positions="guessing no";;
-           beos*)           gl_cv_func_printf_positions="guessing no";;
-                            # Guess yes on Android.
-           linux*-android*) gl_cv_func_printf_positions="guessing yes";;
-                            # Guess no on native Windows.
-           mingw* | pw*)    gl_cv_func_printf_positions="guessing no";;
-           *)               gl_cv_func_printf_positions="guessing yes";;
+             gl_cv_func_printf_positions="guessing no";;
+           beos*)
+             gl_cv_func_printf_positions="guessing no";;
+             # Guess yes on Android.
+           linux*-android*)
+             gl_cv_func_printf_positions="guessing yes";;
+             # Guess no on native Windows.
+           mingw* | windows* | pw*)
+             gl_cv_func_printf_positions="guessing no";;
+           *)
+             gl_cv_func_printf_positions="guessing yes";;
          esac
 changequote([,])dnl
         ])
@@ -900,19 +1173,125 @@ int main ()
         [
 changequote(,)dnl
          case "$host_os" in
-           cygwin*)         gl_cv_func_printf_flag_grouping="guessing no";;
-           netbsd*)         gl_cv_func_printf_flag_grouping="guessing no";;
-                            # Guess no on Android.
-           linux*-android*) gl_cv_func_printf_flag_grouping="guessing no";;
-                            # Guess no on native Windows.
-           mingw* | pw*)    gl_cv_func_printf_flag_grouping="guessing no";;
-           *)               gl_cv_func_printf_flag_grouping="guessing yes";;
+           cygwin*)                 gl_cv_func_printf_flag_grouping="guessing no";;
+           netbsd*)                 gl_cv_func_printf_flag_grouping="guessing no";;
+                                    # Guess no on Android.
+           linux*-android*)         gl_cv_func_printf_flag_grouping="guessing no";;
+                                    # Guess no on native Windows.
+           mingw* | windows* | pw*) gl_cv_func_printf_flag_grouping="guessing no";;
+           *)                       gl_cv_func_printf_flag_grouping="guessing yes";;
          esac
 changequote([,])dnl
         ])
     ])
 ])
 
+dnl Test whether the *printf family of functions supports POSIX/XSI format
+dnl strings with the ' flag for grouping of decimal digits on integers,
+dnl together with a precision.
+dnl Result is gl_cv_func_printf_flag_grouping_int_precision.
+
+AC_DEFUN([gl_PRINTF_FLAG_GROUPING_INT_PRECISION],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CACHE_CHECK([whether printf supports grouping on integers with a precision],
+    [gl_cv_func_printf_flag_grouping_int_precision],
+    [
+      dnl Prepare a guess, used when cross-compiling or when specific locales
+      dnl are not available.
+      case "$host_os" in
+        # Guess no on FreeBSD, NetBSD, Solaris, Cygwin, Haiku.
+        freebsd* | dragonfly* | netbsd* | solaris* | cygwin* | haiku*)
+          gl_cv_func_printf_flag_grouping_int_precision="guessing no";;
+        *)
+          gl_cv_func_printf_flag_grouping_int_precision="guessing yes";;
+      esac
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdio.h>
+#include <string.h>
+static char buf[100];
+int main ()
+{
+  if (setlocale (LC_ALL, "fr_FR.UTF-8") != NULL
+      || setlocale (LC_ALL, "fr_FR") != NULL
+      || setlocale (LC_ALL, "fr_FR.ISO-8859-1") != NULL
+      || setlocale (LC_ALL, "fr_FR.ISO8859-1") != NULL)
+    {
+      if (sprintf (buf, "%'.10d", 1000) < 0)
+        return 1;
+      if (strlen (buf) == 10 && strcmp (buf, "0000001000") != 0)
+        /* The sprintf implementation has produced fewer than 10 digits.  */
+        return 2;
+      else
+        return 0;
+    }
+  return 3;
+}]])],
+        [gl_cv_func_printf_flag_grouping_int_precision=yes],
+        [if test $? = 2; then
+           gl_cv_func_printf_flag_grouping_int_precision=no
+         fi
+        ],
+        [:])
+    ])
+])
+
+dnl Test whether the *printf family of functions supports POSIX/XSI format
+dnl strings with the ' flag for grouping of decimal digits, when the thousands
+dnl separator is a multibyte character (such as U+00A0 or U+202F in a UTF-8
+dnl locale).
+dnl Result is gl_cv_func_printf_flag_grouping_multibyte.
+
+AC_DEFUN([gl_PRINTF_FLAG_GROUPING_MULTIBYTE],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CACHE_CHECK([whether printf supports grouping with a multibyte separator],
+    [gl_cv_func_printf_flag_grouping_multibyte],
+    [
+      dnl Prepare a guess, used when cross-compiling or when specific locales
+      dnl are not available.
+      case "$host_os" in
+        # Guess no on NetBSD and Solaris 11 OpenIndiana.
+        netbsd* | solaris*)
+          gl_cv_func_printf_flag_grouping_multibyte="guessing no";;
+        *)
+          gl_cv_func_printf_flag_grouping_multibyte="guessing yes";;
+      esac
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdio.h>
+#include <string.h>
+static char buf[100];
+int main ()
+{
+  if (setlocale (LC_ALL, "fr_FR.UTF-8") == NULL)
+    return 0;
+  if (sprintf (buf, "%'.0f", 1000.0) < 0)
+    return 1;
+  if (strlen (localeconv ()->thousands_sep) > 1)
+    {
+      if (strlen (buf) <= 4 + 1)
+        return 2;
+      else
+        return 3;
+    }
+  return 0;
+}]])],
+        [:],
+        [case $? in
+           2) gl_cv_func_printf_flag_grouping_multibyte=no ;;
+           3) gl_cv_func_printf_flag_grouping_multibyte=yes ;;
+         esac
+        ],
+        [:])
+    ])
+])
+
 dnl Test whether the *printf family of functions supports the - flag correctly.
 dnl (ISO C99.) See
 dnl <https://lists.gnu.org/r/bug-coreutils/2008-02/msg00035.html>
@@ -943,16 +1322,16 @@ int main ()
         [
 changequote(,)dnl
          case "$host_os" in
-                            # Guess yes on HP-UX 11.
-           hpux11*)         gl_cv_func_printf_flag_leftadjust="guessing yes";;
-                            # Guess no on HP-UX 10 and older.
-           hpux*)           gl_cv_func_printf_flag_leftadjust="guessing no";;
-                            # Guess yes on Android.
-           linux*-android*) gl_cv_func_printf_flag_leftadjust="guessing yes";;
-                            # Guess yes on native Windows.
-           mingw*)          gl_cv_func_printf_flag_leftadjust="guessing yes";;
-                            # Guess yes otherwise.
-           *)               gl_cv_func_printf_flag_leftadjust="guessing yes";;
+                              # Guess yes on HP-UX 11.
+           hpux11*)           gl_cv_func_printf_flag_leftadjust="guessing yes";;
+                              # Guess no on HP-UX 10 and older.
+           hpux*)             gl_cv_func_printf_flag_leftadjust="guessing no";;
+                              # Guess yes on Android.
+           linux*-android*)   gl_cv_func_printf_flag_leftadjust="guessing yes";;
+                              # Guess yes on native Windows.
+           mingw* | windows*) gl_cv_func_printf_flag_leftadjust="guessing yes";;
+                              # Guess yes otherwise.
+           *)                 gl_cv_func_printf_flag_leftadjust="guessing yes";;
          esac
 changequote([,])dnl
         ])
@@ -990,18 +1369,62 @@ int main ()
         [
 changequote(,)dnl
          case "$host_os" in
-                            # Guess yes on glibc systems.
-           *-gnu* | gnu*)   gl_cv_func_printf_flag_zero="guessing yes";;
-                            # Guess yes on musl systems.
-           *-musl*)         gl_cv_func_printf_flag_zero="guessing yes";;
-                            # Guess yes on BeOS.
-           beos*)           gl_cv_func_printf_flag_zero="guessing yes";;
-                            # Guess no on Android.
-           linux*-android*) gl_cv_func_printf_flag_zero="guessing no";;
-                            # Guess no on native Windows.
-           mingw*)          gl_cv_func_printf_flag_zero="guessing no";;
-                            # If we don't know, obey --enable-cross-guesses.
-           *)               gl_cv_func_printf_flag_zero="$gl_cross_guess_normal";;
+                               # Guess yes on glibc systems.
+           *-gnu* | gnu*)      gl_cv_func_printf_flag_zero="guessing yes";;
+                               # Guess yes on musl systems.
+           *-musl* | midipix*) gl_cv_func_printf_flag_zero="guessing yes";;
+                               # Guess yes on BeOS.
+           beos*)              gl_cv_func_printf_flag_zero="guessing yes";;
+                               # Guess no on Android.
+           linux*-android*)    gl_cv_func_printf_flag_zero="guessing no";;
+                               # Guess no on native Windows.
+           mingw* | windows*)  gl_cv_func_printf_flag_zero="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_printf_flag_zero="$gl_cross_guess_normal";;
+         esac
+changequote([,])dnl
+        ])
+    ])
+])
+
+dnl Test whether the *printf family of functions supports the # flag with a
+dnl zero precision and a zero value in the 'x' and 'X' directives correctly.
+dnl ISO C and POSIX specify that for the 'd', 'i', 'b', 'o', 'u', 'x', 'X'
+dnl directives: "The result of converting a zero value with a precision of
+dnl zero is no characters."  But on Mac OS X 10.5, for the 'x', 'X' directives,
+dnl when a # flag is present, the output is "0" instead of "".
+dnl Result is gl_cv_func_printf_flag_alt_precision_zero.
+
+AC_DEFUN([gl_PRINTF_FLAG_ALT_PRECISION_ZERO],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether printf supports the alternative flag with a zero precision],
+    [gl_cv_func_printf_flag_alt_precision_zero],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+static char buf[10];
+int main ()
+{
+  int result = 0;
+  if (sprintf (buf, "%#.0x %d", 0, 33, 44) > 0 + 3)
+    result |= 1;
+  return result;
+}]])],
+        [gl_cv_func_printf_flag_alt_precision_zero=yes],
+        [gl_cv_func_printf_flag_alt_precision_zero=no],
+        [
+changequote(,)dnl
+         case "$host_os" in
+           # Guess no only on macOS 10..12 systems.
+           darwin[0-9] | darwin[0-9].* | \
+           darwin1[0-9] | darwin1[0-9].* | \
+           darwin2[0-1] | darwin2[0-1].*)
+                    gl_cv_func_printf_flag_alt_precision_zero="guessing no" ;;
+           darwin*) gl_cv_func_printf_flag_alt_precision_zero="guessing yes" ;;
+           *)       gl_cv_func_printf_flag_alt_precision_zero="guessing yes" ;;
          esac
 changequote([,])dnl
         ])
@@ -1054,12 +1477,12 @@ int main ()
 changequote(,)dnl
          case "$host_os" in
            # Guess no only on Solaris, native Windows, and BeOS systems.
-           solaris*)        gl_cv_func_printf_precision="guessing no" ;;
-           mingw* | pw*)    gl_cv_func_printf_precision="guessing no" ;;
-           beos*)           gl_cv_func_printf_precision="guessing no" ;;
-                            # Guess yes on Android.
-           linux*-android*) gl_cv_func_printf_precision="guessing yes" ;;
-           *)               gl_cv_func_printf_precision="guessing yes" ;;
+           solaris*)                gl_cv_func_printf_precision="guessing no" ;;
+           mingw* | windows* | pw*) gl_cv_func_printf_precision="guessing no" ;;
+           beos*)                   gl_cv_func_printf_precision="guessing no" ;;
+                                    # Guess yes on Android.
+           linux*-android*)         gl_cv_func_printf_precision="guessing yes" ;;
+           *)                       gl_cv_func_printf_precision="guessing yes" ;;
          esac
 changequote([,])dnl
         ])
@@ -1239,7 +1662,7 @@ changequote(,)dnl
                                  # Guess yes on glibc systems.
            *-gnu* | gnu*)        gl_cv_func_snprintf_truncation_c99="guessing yes";;
                                  # Guess yes on musl systems.
-           *-musl*)              gl_cv_func_snprintf_truncation_c99="guessing yes";;
+           *-musl* | midipix*)   gl_cv_func_snprintf_truncation_c99="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_snprintf_truncation_c99="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_snprintf_truncation_c99="guessing yes";;
@@ -1275,7 +1698,7 @@ changequote(,)dnl
                                  # Guess yes on Android.
            linux*-android*)      gl_cv_func_snprintf_truncation_c99="guessing yes";;
                                  # Guess no on native Windows.
-           mingw*)               gl_cv_func_snprintf_truncation_c99="guessing no";;
+           mingw* | windows*)    gl_cv_func_snprintf_truncation_c99="guessing no";;
                                  # If we don't know, obey --enable-cross-guesses.
            *)                    gl_cv_func_snprintf_truncation_c99="$gl_cross_guess_normal";;
          esac
@@ -1344,7 +1767,7 @@ changequote(,)dnl
                                  # Guess yes on glibc systems.
            *-gnu* | gnu*)        gl_cv_func_snprintf_retval_c99="guessing yes";;
                                  # Guess yes on musl systems.
-           *-musl*)              gl_cv_func_snprintf_retval_c99="guessing yes";;
+           *-musl* | midipix*)   gl_cv_func_snprintf_retval_c99="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_snprintf_retval_c99="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_snprintf_retval_c99="guessing yes";;
@@ -1372,7 +1795,8 @@ changequote(,)dnl
            linux*-android*)      gl_cv_func_snprintf_retval_c99="guessing yes";;
 changequote([,])dnl
                                  # Guess yes on MSVC, no on mingw.
-           mingw*)               AC_EGREP_CPP([Known], [
+           windows*-msvc*)       gl_cv_func_snprintf_retval_c99="guessing yes" ;;
+           mingw* | windows*)    AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
@@ -1401,8 +1825,14 @@ AC_DEFUN([gl_SNPRINTF_DIRECTIVE_N],
     [
       AC_RUN_IFELSE(
         [AC_LANG_SOURCE([[
+#include <signal.h>
 #include <stdio.h>
 #include <string.h>
+#if defined _WIN32 && !defined __CYGWIN__
+# include <stdlib.h>
+#else
+# include <unistd.h>
+#endif
 #if HAVE_SNPRINTF
 # define my_snprintf snprintf
 #else
@@ -1417,11 +1847,18 @@ static int my_snprintf (char *buf, int size, const char *format, ...)
   return ret;
 }
 #endif
+static void
+abort_handler (int sig)
+{
+  (void) sig;
+  _exit (1);
+}
 static char fmtstring[10];
 static char buf[100];
 int main ()
 {
   int count = -1;
+  signal (SIGABRT, abort_handler);
   /* Copy the format string.  Some systems (glibc with _FORTIFY_SOURCE=2)
      support %n in format strings in read-only memory but not in writable
      memory.  */
@@ -1447,7 +1884,7 @@ int main ()
                                  ;;
 changequote(,)dnl
                                  # Guess yes on musl systems.
-           *-musl*)              gl_cv_func_snprintf_directive_n="guessing yes";;
+           *-musl* | midipix*)   gl_cv_func_snprintf_directive_n="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_snprintf_directive_n="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_snprintf_directive_n="guessing yes";;
@@ -1476,7 +1913,7 @@ changequote(,)dnl
                                  # Guess no on Android.
            linux*-android*)      gl_cv_func_snprintf_directive_n="guessing no";;
                                  # Guess no on native Windows.
-           mingw*)               gl_cv_func_snprintf_directive_n="guessing no";;
+           mingw* | windows*)    gl_cv_func_snprintf_directive_n="guessing no";;
                                  # If we don't know, obey --enable-cross-guesses.
            *)                    gl_cv_func_snprintf_directive_n="$gl_cross_guess_normal";;
 changequote([,])dnl
@@ -1524,11 +1961,11 @@ int main()
         [gl_cv_func_snprintf_size1=yes],
         [gl_cv_func_snprintf_size1=no],
         [case "$host_os" in
-                            # Guess yes on Android.
-           linux*-android*) gl_cv_func_snprintf_size1="guessing yes" ;;
-                            # Guess yes on native Windows.
-           mingw*)          gl_cv_func_snprintf_size1="guessing yes" ;;
-           *)               gl_cv_func_snprintf_size1="guessing yes" ;;
+                              # Guess yes on Android.
+           linux*-android*)   gl_cv_func_snprintf_size1="guessing yes" ;;
+                              # Guess yes on native Windows.
+           mingw* | windows*) gl_cv_func_snprintf_size1="guessing yes" ;;
+           *)                 gl_cv_func_snprintf_size1="guessing yes" ;;
          esac
         ])
     ])
@@ -1601,128 +2038,324 @@ int main()
         [
 changequote(,)dnl
          case "$host_os" in
-                                 # Guess yes on glibc systems.
-           *-gnu* | gnu*)        gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on musl systems.
-           *-musl*)              gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on FreeBSD >= 5.
-           freebsd[1-4].*)       gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
-           freebsd* | kfreebsd*) gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-           midnightbsd*)         gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on Mac OS X >= 10.3.
-           darwin[1-6].*)        gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
-           darwin*)              gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on Cygwin.
-           cygwin*)              gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on Solaris >= 2.6.
+                                    # Guess yes on glibc systems.
+           *-gnu* | gnu*)           gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on musl systems.
+           *-musl* | midipix*)      gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on FreeBSD >= 5.
+           freebsd[1-4].*)          gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
+           freebsd* | kfreebsd*)    gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+           midnightbsd*)            gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on Mac OS X >= 10.3.
+           darwin[1-6].*)           gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
+           darwin*)                 gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on Cygwin.
+           cygwin*)                 gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on Solaris >= 2.6.
            solaris2.[0-5] | solaris2.[0-5].*)
-                                 gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
-           solaris*)             gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on AIX >= 4.
-           aix[1-3]*)            gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
-           aix*)                 gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on IRIX >= 6.5.
-           irix6.5)              gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on NetBSD >= 3.
+                                    gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
+           solaris*)                gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on AIX >= 4.
+           aix[1-3]*)               gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
+           aix*)                    gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on IRIX >= 6.5.
+           irix6.5)                 gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on NetBSD >= 3.
            netbsd[1-2]* | netbsdelf[1-2]* | netbsdaout[1-2]* | netbsdcoff[1-2]*)
-                                 gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
-           netbsd*)              gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on BeOS.
-           beos*)                gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on Android.
-           linux*-android*)      gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # Guess yes on native Windows.
-           mingw* | pw*)         gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
-                                 # If we don't know, obey --enable-cross-guesses.
-           *)                    gl_cv_func_vsnprintf_zerosize_c99="$gl_cross_guess_normal";;
+                                    gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
+           netbsd*)                 gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on BeOS.
+           beos*)                   gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on Android.
+           linux*-android*)         gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # Guess yes on native Windows.
+           mingw* | windows* | pw*) gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+                                    # If we don't know, obey --enable-cross-guesses.
+           *)                       gl_cv_func_vsnprintf_zerosize_c99="$gl_cross_guess_normal";;
          esac
 changequote([,])dnl
         ])
     ])
 ])
 
+dnl Test whether the swprintf function works correctly when it produces output
+dnl that contains null wide characters.
+dnl Result is gl_cv_func_swprintf_works.
+
+AC_DEFUN([gl_SWPRINTF_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_FUNCS_ONCE([swprintf])
+  AC_CACHE_CHECK([whether swprintf works],
+    [gl_cv_func_swprintf_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#ifndef __USE_MINGW_ANSI_STDIO
+# define __USE_MINGW_ANSI_STDIO 1
+#endif
+#include <stdio.h>
+#include <wchar.h>
+int main()
+{
+  int result = 0;
+  { /* This test fails on musl libc 1.2.3, FreeBSD, NetBSD, OpenBSD, macOS, AIX.  */
+    wchar_t buf[5] = { 0xBEEF, 0xBEEF, 0xBEEF, 0xBEEF, 0xBEEF };
+    int ret = swprintf (buf, 4, L"%cz", '\0');
+    /* Expected result:
+         ret = 2, buf[0] = 0x0, buf[1] = 0x7a, buf[2] = 0x0, buf[3] = 0xbeef
+       musl libc 1.2.3:
+         ret = 2, buf[0] = 0x0, buf[1] = 0x0, buf[2] = 0x0, buf[3] = 0x0
+         Reported at <https://www.openwall.com/lists/musl/2023/03/22/9>.
+       FreeBSD 13.1, NetBSD 9.0, OpenBSD 7.2, macOS 12.5, AIX 7.2:
+         ret = 2, buf[0] = 0x0, buf[1] = 0xbeef, buf[2] = 0xbeef, buf[3] = 0xbeef
+     */
+    if (ret < 0 || buf[1] != 'z')
+      result |= 1;
+  }
+  { /* This test fails on mingw.  */
+    wchar_t buf[2];
+    int ret = swprintf (buf, 2, L"%lc", (wint_t)0);
+    /* Expected: ret = 1
+       mingw:    ret = 0
+     */
+    if (ret != 1)
+      result |= 2;
+  }
+  return result;
+}]])],
+        [gl_cv_func_swprintf_works=yes],
+        [gl_cv_func_swprintf_works=no],
+        [case "$host_os" in
+                                    # Guess yes on glibc systems.
+           *-gnu* | gnu*)           gl_cv_func_swprintf_works="guessing yes";;
+                                    # Guess no on musl systems.
+           *-musl* | midipix*)      gl_cv_func_swprintf_works="guessing no";;
+                                    # Guess no on FreeBSD, NetBSD, OpenBSD, macOS, AIX.
+           freebsd* | midnightbsd* | netbsd* | openbsd* | darwin* | aix*)
+                                    gl_cv_func_swprintf_works="guessing no";;
+                                    # Guess no on native Windows.
+           mingw* | windows* | pw*) gl_cv_func_swprintf_works="guessing no";;
+                                    # If we don't know, obey --enable-cross-guesses.
+           *)                       gl_cv_func_swprintf_works="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
+dnl Test whether the *wprintf family of functions supports the 'a' and 'A'
+dnl conversion specifier for hexadecimal output of 'long double' numbers.
+dnl (ISO C99, POSIX:2001)
+dnl Result is gl_cv_func_swprintf_directive_la.
+
+AC_DEFUN([gl_SWPRINTF_DIRECTIVE_LA],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether swprintf supports the 'La' and 'LA' directives],
+    [gl_cv_func_swprintf_directive_la],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <wchar.h>
+static wchar_t buf[100];
+int main ()
+{
+  int result = 0;
+  /* This catches a glibc 2.15, Haiku 2022, NetBSD 10.0 bug.  */
+  if (swprintf (buf, sizeof (buf) / sizeof (wchar_t),
+                L"%La %d", 3.1416015625L, 33, 44, 55) < 0
+      || (wcscmp (buf, L"0x1.922p+1 33") != 0
+          && wcscmp (buf, L"0x3.244p+0 33") != 0
+          && wcscmp (buf, L"0x6.488p-1 33") != 0
+          && wcscmp (buf, L"0xc.91p-2 33") != 0))
+    result |= 1;
+  return result;
+}]])],
+        [gl_cv_func_swprintf_directive_la=yes],
+        [gl_cv_func_swprintf_directive_la=no],
+        [case "$host_os" in
+                               # Guess yes on glibc >= 2.17 systems.
+           *-gnu* | gnu*)
+             AC_EGREP_CPP([Unlucky], [
+               #include <features.h>
+               #ifdef __GNU_LIBRARY__
+                #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 16) || (__GLIBC__ > 2)) && !defined __UCLIBC__
+                 Unlucky
+                #endif
+               #endif
+               ],
+               [gl_cv_func_swprintf_directive_la="guessing yes"],
+               [gl_cv_func_swprintf_directive_la="guessing no"])
+             ;;
+                               # Guess yes on musl systems.
+           *-musl* | midipix*) gl_cv_func_swprintf_directive_la="guessing yes";;
+                               # Guess yes on Android.
+           linux*-android*)    gl_cv_func_swprintf_directive_la="guessing yes";;
+                               # Guess no on NetBSD.
+           netbsd*)            gl_cv_func_swprintf_directive_la="guessing no";;
+                               # Guess no on native Windows.
+           mingw* | windows*)  gl_cv_func_swprintf_directive_la="guessing no";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_swprintf_directive_la="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
+dnl Test whether the *wprintf family of functions supports the 'lc' conversion
+dnl specifier for all wide characters.
+dnl (ISO C11, POSIX:2001)
+dnl Result is gl_cv_func_swprintf_directive_lc.
+
+AC_DEFUN([gl_SWPRINTF_DIRECTIVE_LC],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether swprintf supports the 'lc' directive],
+    [gl_cv_func_swprintf_directive_lc],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <wchar.h>
+static wchar_t buf[100];
+static wint_t L_invalid = (wchar_t) 0x76543210;
+int main ()
+{
+  int result = 0;
+  /* This catches a musl libc 1.2.4, Android bug.
+     Reported at <https://www.openwall.com/lists/musl/2023/06/12/3>. */
+  if (swprintf (buf, sizeof (buf) / sizeof (wchar_t),
+                L"%lc %d", L_invalid, 33, 44, 55) < 0)
+    result |= 1;
+  return result;
+}]])],
+        [gl_cv_func_swprintf_directive_lc=yes],
+        [gl_cv_func_swprintf_directive_lc=no],
+        [case "$host_os" in
+                               # Guess yes on glibc systems.
+           *-gnu* | gnu*)      gl_cv_func_swprintf_directive_lc="guessing yes";;
+                               # Guess no on musl systems.
+           *-musl* | midipix*) gl_cv_func_swprintf_directive_lc="guessing no";;
+                               # Guess no on Android.
+           linux*-android*)    gl_cv_func_swprintf_directive_lc="guessing no";;
+                               # Guess yes on native Windows.
+           mingw* | windows*)  gl_cv_func_swprintf_directive_lc="guessing yes";;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_swprintf_directive_lc="$gl_cross_guess_normal";;
+         esac
+        ])
+    ])
+])
+
 dnl The results of these tests on various platforms are:
 dnl
 dnl 1 = gl_PRINTF_SIZES_C99
-dnl 2 = gl_PRINTF_LONG_DOUBLE
-dnl 3 = gl_PRINTF_INFINITE
-dnl 4 = gl_PRINTF_INFINITE_LONG_DOUBLE
-dnl 5 = gl_PRINTF_DIRECTIVE_A
-dnl 6 = gl_PRINTF_DIRECTIVE_F
-dnl 7 = gl_PRINTF_DIRECTIVE_N
-dnl 8 = gl_PRINTF_DIRECTIVE_LS
-dnl 9 = gl_PRINTF_POSITIONS
-dnl 10 = gl_PRINTF_FLAG_GROUPING
-dnl 11 = gl_PRINTF_FLAG_LEFTADJUST
-dnl 12 = gl_PRINTF_FLAG_ZERO
-dnl 13 = gl_PRINTF_PRECISION
-dnl 14 = gl_PRINTF_ENOMEM
-dnl 15 = gl_SNPRINTF_PRESENCE
-dnl 16 = gl_SNPRINTF_TRUNCATION_C99
-dnl 17 = gl_SNPRINTF_RETVAL_C99
-dnl 18 = gl_SNPRINTF_DIRECTIVE_N
-dnl 19 = gl_SNPRINTF_SIZE1
-dnl 20 = gl_VSNPRINTF_ZEROSIZE_C99
+dnl 2 = gl_PRINTF_SIZES_C23
+dnl 3 = gl_PRINTF_LONG_DOUBLE
+dnl 4 = gl_PRINTF_INFINITE
+dnl 5 = gl_PRINTF_INFINITE_LONG_DOUBLE
+dnl 6 = gl_PRINTF_DIRECTIVE_A
+dnl 7 = gl_PRINTF_DIRECTIVE_B
+dnl 8 = gl_PRINTF_DIRECTIVE_UPPERCASE_B
+dnl 9 = gl_PRINTF_DIRECTIVE_F
+dnl 10 = gl_PRINTF_DIRECTIVE_N
+dnl 11 = gl_PRINTF_DIRECTIVE_LS
+dnl 12 = gl_PRINTF_DIRECTIVE_LC
+dnl 13 = gl_PRINTF_POSITIONS
+dnl 14 = gl_PRINTF_FLAG_GROUPING
+dnl 15 = gl_PRINTF_FLAG_GROUPING_INT_PRECISION
+dnl 16 = gl_PRINTF_FLAG_GROUPING_MULTIBYTE
+dnl 17 = gl_PRINTF_FLAG_LEFTADJUST
+dnl 18 = gl_PRINTF_FLAG_ZERO
+dnl 19 = gl_PRINTF_FLAG_ALT_PRECISION_ZERO
+dnl 20 = gl_PRINTF_PRECISION
+dnl 21 = gl_PRINTF_ENOMEM
+dnl 22 = gl_SNPRINTF_PRESENCE
+dnl 23 = gl_SNPRINTF_TRUNCATION_C99
+dnl 24 = gl_SNPRINTF_RETVAL_C99
+dnl 25 = gl_SNPRINTF_DIRECTIVE_N
+dnl 26 = gl_SNPRINTF_SIZE1
+dnl 27 = gl_VSNPRINTF_ZEROSIZE_C99
+dnl 28 = gl_SWPRINTF_WORKS
+dnl 29 = gl_SWPRINTF_DIRECTIVE_LA
+dnl 30 = gl_SWPRINTF_DIRECTIVE_LC
 dnl
 dnl 1 = checking whether printf supports size specifiers as in C99...
-dnl 2 = checking whether printf supports 'long double' arguments...
-dnl 3 = checking whether printf supports infinite 'double' arguments...
-dnl 4 = checking whether printf supports infinite 'long double' arguments...
-dnl 5 = checking whether printf supports the 'a' and 'A' directives...
-dnl 6 = checking whether printf supports the 'F' directive...
-dnl 7 = checking whether printf supports the 'n' directive...
-dnl 8 = checking whether printf supports the 'ls' directive...
-dnl 9 = checking whether printf supports POSIX/XSI format strings with positions...
-dnl 10 = checking whether printf supports the grouping flag...
-dnl 11 = checking whether printf supports the left-adjust flag correctly...
-dnl 12 = checking whether printf supports the zero flag correctly...
-dnl 13 = checking whether printf supports large precisions...
-dnl 14 = checking whether printf survives out-of-memory conditions...
-dnl 15 = checking for snprintf...
-dnl 16 = checking whether snprintf truncates the result as in C99...
-dnl 17 = checking whether snprintf returns a byte count as in C99...
-dnl 18 = checking whether snprintf fully supports the 'n' directive...
-dnl 19 = checking whether snprintf respects a size of 1...
-dnl 20 = checking whether vsnprintf respects a zero size as in C99...
+dnl 2 = checking whether printf supports size specifiers as in C23...
+dnl 3 = checking whether printf supports 'long double' arguments...
+dnl 4 = checking whether printf supports infinite 'double' arguments...
+dnl 5 = checking whether printf supports infinite 'long double' arguments...
+dnl 6 = checking whether printf supports the 'a' and 'A' directives...
+dnl 7 = checking whether printf supports the 'b' directive...
+dnl 8 = checking whether printf supports the 'B' directive...
+dnl 9 = checking whether printf supports the 'F' directive...
+dnl 10 = checking whether printf supports the 'n' directive...
+dnl 11 = checking whether printf supports the 'ls' directive...
+dnl 12 = checking whether printf supports the 'lc' directive correctly...
+dnl 13 = checking whether printf supports POSIX/XSI format strings with positions...
+dnl 14 = checking whether printf supports the grouping flag...
+dnl 15 = checking whether printf supports grouping on integers with a precision...
+dnl 16 = checking whether printf supports grouping with a multibyte separator...
+dnl 17 = checking whether printf supports the left-adjust flag correctly...
+dnl 18 = checking whether printf supports the zero flag correctly...
+dnl 19 = checking whether printf supports the alternative flag with a zero precision...
+dnl 20 = checking whether printf supports large precisions...
+dnl 21 = checking whether printf survives out-of-memory conditions...
+dnl 22 = checking for snprintf...
+dnl 23 = checking whether snprintf truncates the result as in C99...
+dnl 24 = checking whether snprintf returns a byte count as in C99...
+dnl 25 = checking whether snprintf fully supports the 'n' directive...
+dnl 26 = checking whether snprintf respects a size of 1...
+dnl 27 = checking whether vsnprintf respects a zero size as in C99...
+dnl 28 = checking whether swprintf works...
+dnl 29 = checking whether swprintf supports the 'La' and 'LA' directives...
+dnl 30 = checking whether swprintf supports the 'lc' directive...
 dnl
 dnl . = yes, # = no.
 dnl
-dnl                                  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20
-dnl   glibc 2.5                      .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
-dnl   glibc 2.3.6                    .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
-dnl   FreeBSD 13.0                   .  .  .  .  #  .  .  .  .  .  .  .  .  #  .  .  .  .  .  .
-dnl   FreeBSD 5.4, 6.1               .  .  .  .  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
-dnl   Mac OS X 10.13.5               .  .  .  #  #  .  #  .  .  .  .  .  .  .  .  .  .  #  .  .
-dnl   Mac OS X 10.5.8                .  .  .  #  #  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .
-dnl   Mac OS X 10.3.9                .  .  .  .  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
-dnl   OpenBSD 6.0, 6.7               .  .  .  .  #  .  .  .  .  .  .  .  .  #  .  .  .  .  .  .
-dnl   OpenBSD 3.9, 4.0               .  .  #  #  #  #  .  #  .  #  .  #  .  #  .  .  .  .  .  .
-dnl   Cygwin 1.7.0 (2009)            .  .  .  #  .  .  .  ?  .  .  .  .  .  ?  .  .  .  .  .  .
-dnl   Cygwin 1.5.25 (2008)           .  .  .  #  #  .  .  #  .  .  .  .  .  #  .  .  .  .  .  .
-dnl   Cygwin 1.5.19 (2006)           #  .  .  #  #  #  .  #  .  #  .  #  #  #  .  .  .  .  .  .
-dnl   Solaris 11.4                   .  .  #  #  #  .  .  #  .  .  .  #  .  .  .  .  .  .  .  .
-dnl   Solaris 11.3                   .  .  .  .  #  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .
-dnl   Solaris 11.0                   .  .  #  #  #  .  .  #  .  .  .  #  .  .  .  .  .  .  .  .
-dnl   Solaris 10                     .  .  #  #  #  .  .  #  .  .  .  #  #  .  .  .  .  .  .  .
-dnl   Solaris 2.6 ... 9              #  .  #  #  #  #  .  #  .  .  .  #  #  .  .  .  #  .  .  .
-dnl   Solaris 2.5.1                  #  .  #  #  #  #  .  #  .  .  .  #  .  .  #  #  #  #  #  #
-dnl   AIX 7.1                        .  .  #  #  #  .  .  .  .  .  .  #  #  .  .  .  .  .  .  .
-dnl   AIX 5.2                        .  .  #  #  #  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .
-dnl   AIX 4.3.2, 5.1                 #  .  #  #  #  #  .  .  .  .  .  #  .  .  .  .  #  .  .  .
-dnl   HP-UX 11.31                    .  .  .  .  #  .  .  .  .  .  .  #  .  .  .  .  #  #  .  .
-dnl   HP-UX 11.{00,11,23}            #  .  .  .  #  #  .  .  .  .  .  #  .  .  .  .  #  #  .  #
-dnl   HP-UX 10.20                    #  .  #  .  #  #  .  ?  .  .  #  #  .  .  .  .  #  #  ?  #
-dnl   IRIX 6.5                       #  .  #  #  #  #  .  #  .  .  .  #  .  .  .  .  #  .  .  .
-dnl   OSF/1 5.1                      #  .  #  #  #  #  .  .  .  .  .  #  .  .  .  .  #  .  .  #
-dnl   OSF/1 4.0d                     #  .  #  #  #  #  .  .  .  .  .  #  .  .  #  #  #  #  #  #
-dnl   NetBSD 9.0                     .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
-dnl   NetBSD 5.0                     .  .  .  #  #  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .
-dnl   NetBSD 4.0                     .  ?  ?  ?  ?  ?  .  ?  .  ?  ?  ?  ?  ?  .  .  .  ?  ?  ?
-dnl   NetBSD 3.0                     .  .  .  .  #  #  .  ?  #  #  ?  #  .  #  .  .  .  .  .  .
-dnl   Haiku                          .  .  .  #  #  #  .  #  .  .  .  .  .  ?  .  .  ?  .  .  .
-dnl   BeOS                           #  #  .  #  #  #  .  ?  #  .  ?  .  #  ?  .  .  ?  .  .  .
-dnl   Android 4.3                    .  .  #  #  #  #  #  #  .  #  .  #  .  #  .  .  .  #  .  .
-dnl   old mingw / msvcrt             #  #  #  #  #  #  .  .  #  #  .  #  #  ?  .  #  #  #  .  .
-dnl   MSVC 9                         #  #  #  #  #  #  #  .  #  #  .  #  #  ?  #  #  #  #  .  .
-dnl   mingw 2009-2011                .  #  .  #  .  .  .  .  #  #  .  .  .  ?  .  .  .  .  .  .
-dnl   mingw-w64 2011                 #  #  #  #  #  #  .  .  #  #  .  #  #  ?  .  #  #  #  .  .
+dnl                                  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
+dnl   musl libc 1.2.3                .  #  .  .  .  .  #  #  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  #  .  #
+dnl   glibc 2.35                     .  #  .  .  .  .  .  .  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
+dnl   glibc 2.5                      .  #  .  .  .  .  #  #  .  .  .  .  .  .  #  .  .  .  .  .  .  .  .  .  .  .  .  .  #  .
+dnl   glibc 2.3.6                    .  #  .  .  .  #  #  #  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  #  .
+dnl   FreeBSD 14.0                   .  .  .  .  .  #  .  .  .  .  .  .  .  .  #  .  .  .  .  .  #  .  .  .  .  .  .  #  .  #
+dnl   FreeBSD 13.0                   .  #  .  .  .  #  #  #  .  .  .  .  .  .  #  .  .  .  .  .  #  .  .  .  .  .  .  #  .  #
+dnl   FreeBSD 5.4, 6.1               .  #  .  .  .  #  #  #  .  .  .  .  .  .  .  .  .  #  ?  .  #  .  .  .  .  .  .  #  ?  ?
+dnl   Mac OS X 10.13.5               .  #  .  .  #  #  #  #  .  #  .  .  .  .  ?  ?  .  .  .  .  .  .  .  .  #  .  .  #  ?  ?
+dnl   Mac OS X 10.5.8                .  #  .  .  #  #  #  #  .  .  .  .  .  .  ?  ?  .  #  #  .  .  .  .  .  .  .  .  #  ?  ?
+dnl   Mac OS X 10.3.9                .  #  .  .  .  #  #  #  .  .  .  .  .  .  ?  ?  .  #  #  .  #  .  .  .  .  .  .  #  ?  ?
+dnl   OpenBSD 6.0, 6.7               .  #  .  .  .  #  #  #  .  .  .  .  .  .  .  .  .  .  .  .  #  .  .  .  .  .  .  #  .  #
+dnl   OpenBSD 3.9, 4.0               .  #  .  #  #  #  #  #  #  .  #  .  .  #  ?  ?  .  #  ?  .  #  .  .  .  .  .  .  #  ?  ?
+dnl   Cygwin 1.7.0 (2009)            .  #  .  .  #  .  #  #  .  .  ?  ?  .  .  ?  ?  .  .  ?  .  ?  .  .  .  .  .  .  ?  ?  ?
+dnl   Cygwin 1.5.25 (2008)           .  #  .  .  #  #  #  #  .  .  #  ?  .  .  ?  ?  .  .  ?  .  #  .  .  .  .  .  .  ?  ?  ?
+dnl   Cygwin 1.5.19 (2006)           #  #  .  .  #  #  #  #  #  .  #  ?  .  #  ?  ?  .  #  ?  #  #  .  .  .  .  .  .  ?  ?  ?
+dnl   Solaris 11.4                   .  #  .  #  #  #  #  #  .  .  #  .  .  .  #  #  .  #  .  .  .  .  .  .  .  .  .  .  #  .
+dnl   Solaris 11.3                   .  #  .  .  .  #  #  #  .  .  #  .  .  .  ?  ?  .  .  .  .  .  .  .  .  .  .  .  .  #  .
+dnl   Solaris 11.0                   .  #  .  #  #  #  #  #  .  .  #  .  .  .  ?  ?  .  #  .  .  .  .  .  .  .  .  .  ?  ?  ?
+dnl   Solaris 10                     .  #  .  #  #  #  #  #  .  .  #  .  .  .  #  #  .  #  .  #  .  .  .  .  .  .  .  .  #  .
+dnl   Solaris 2.6 ... 9              #  #  .  #  #  #  #  #  #  .  #  .  .  .  ?  ?  .  #  ?  #  .  .  .  #  .  .  .  ?  ?  ?
+dnl   Solaris 2.5.1                  #  #  .  #  #  #  #  #  #  .  #  .  .  .  ?  ?  .  #  ?  .  .  #  #  #  #  #  #  ?  ?  ?
+dnl   AIX 7.1                        .  #  .  #  #  #  #  #  .  .  .  .  .  .  .  .  .  #  .  #  .  .  .  .  .  .  .  #  .  .
+dnl   AIX 5.2                        .  #  .  #  #  #  #  #  .  .  .  .  .  .  ?  ?  .  #  ?  .  .  .  .  .  .  .  .  #  ?  ?
+dnl   AIX 4.3.2, 5.1                 #  #  .  #  #  #  #  #  #  .  .  .  .  .  ?  ?  .  #  ?  .  .  .  .  #  .  .  .  #  ?  ?
+dnl   HP-UX 11.31                    .  #  .  .  .  #  #  #  .  .  .  ?  .  .  ?  ?  .  #  ?  .  .  .  .  #  #  .  .  ?  ?  ?
+dnl   HP-UX 11.{00,11,23}            #  #  .  .  .  #  #  #  #  .  .  ?  .  .  ?  ?  .  #  ?  .  .  .  .  #  #  .  #  ?  ?  ?
+dnl   HP-UX 10.20                    #  #  .  #  .  #  #  #  #  .  ?  ?  .  .  ?  ?  #  #  ?  .  .  .  .  #  #  ?  #  ?  ?  ?
+dnl   IRIX 6.5                       #  #  .  #  #  #  #  #  #  .  #  .  .  .  ?  ?  .  #  ?  .  .  .  .  #  .  .  .  #  ?  ?
+dnl   OSF/1 5.1                      #  #  .  #  #  #  #  #  #  .  .  ?  .  .  ?  ?  .  #  ?  .  .  .  .  #  .  .  #  ?  ?  ?
+dnl   OSF/1 4.0d                     #  #  .  #  #  #  #  #  #  .  .  ?  .  .  ?  ?  .  #  ?  .  .  #  #  #  #  #  #  ?  ?  ?
+dnl   NetBSD 9.0                     .  #  .  .  .  #  #  #  .  .  .  .  .  .  #  #  .  .  .  .  .  .  .  .  .  .  .  #  .  #
+dnl   NetBSD 5.0                     .  #  .  .  #  #  #  #  .  .  .  .  .  .  ?  ?  .  #  ?  .  #  .  .  .  .  .  .  #  ?  ?
+dnl   NetBSD 4.0                     .  #  ?  ?  ?  ?  #  #  ?  .  ?  .  .  ?  ?  ?  ?  ?  ?  ?  ?  .  .  .  ?  ?  ?  #  ?  ?
+dnl   NetBSD 3.0                     .  #  .  .  .  #  #  #  #  .  ?  .  #  #  ?  ?  ?  #  ?  .  #  .  .  .  .  .  .  #  ?  ?
+dnl   Haiku                          .  #  .  .  #  #  #  #  #  .  #  ?  .  .  #  .  .  .  ?  .  ?  .  .  ?  .  .  .  .  #  .
+dnl   BeOS                           #  #  #  .  #  #  #  #  #  .  ?  ?  #  .  ?  ?  ?  .  ?  #  ?  .  .  ?  .  .  .  ?  ?  ?
+dnl   Android 4.3                    .  #  .  #  #  #  #  #  #  #  #  ?  .  #  ?  ?  .  #  ?  .  #  .  .  .  #  .  .  ?  ?  ?
+dnl   old mingw / msvcrt             #  #  #  #  #  #  #  #  #  .  .  ?  #  #  ?  ?  .  #  ?  #  ?  .  #  #  #  .  .  #  ?  ?
+dnl   MSVC 9                         #  #  #  #  #  #  #  #  #  #  .  ?  #  #  ?  ?  .  #  ?  #  ?  #  #  #  #  .  .  #  ?  ?
+dnl   mingw 2009-2011                .  #  #  .  #  .  #  #  .  .  .  ?  #  #  ?  ?  .  .  ?  .  ?  .  .  .  .  .  .  #  ?  ?
+dnl   mingw-w64 2011                 #  #  #  #  #  #  #  #  #  .  .  ?  #  #  ?  ?  .  #  ?  #  ?  .  #  #  #  .  .  #  ?  ?
diff --git a/gl/m4/pthread-once.m4 b/gl/m4/pthread-once.m4
new file mode 100644
index 00000000..85549254
--- /dev/null
+++ b/gl/m4/pthread-once.m4
@@ -0,0 +1,83 @@
+# pthread-once.m4
+# serial 6
+dnl Copyright (C) 2019-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_PTHREAD_ONCE],
+[
+  AC_REQUIRE([gl_PTHREAD_H])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_PTHREADLIB])
+
+  if { case "$host_os" in mingw* | windows*) true;; *) false;; esac; } \
+     && test $gl_threads_api = windows; then
+    dnl Choose function names that don't conflict with the mingw-w64 winpthreads
+    dnl library.
+    REPLACE_PTHREAD_ONCE=1
+    PTHREAD_ONCE_LIB=
+  else
+    if test $HAVE_PTHREAD_H = 0; then
+      HAVE_PTHREAD_ONCE=0
+      PTHREAD_ONCE_LIB=
+    else
+      dnl Work around Cygwin 3.5.3 bug.
+      AC_CACHE_CHECK([whether pthread_once works],
+        [gl_cv_func_pthread_once_works],
+        [case "$host_os" in
+           cygwin*) gl_cv_func_pthread_once_works="guessing no" ;;
+           *)       gl_cv_func_pthread_once_works="yes" ;;
+         esac
+        ])
+      case "$gl_cv_func_pthread_once_works" in
+        *yes) ;;
+        *) REPLACE_PTHREAD_ONCE=1 ;;
+      esac
+      dnl Determine whether linking requires $(LIBPMULTITHREAD) or only
+      dnl $(LIBPTHREAD).
+      if test -z "$LIBPTHREAD" && test -n "$LIBPMULTITHREAD"; then
+        AC_CACHE_CHECK([whether pthread_once can be used without linking with libpthread],
+          [gl_cv_func_pthread_once_no_lib],
+          [AC_RUN_IFELSE(
+             [AC_LANG_PROGRAM(
+                [[#include <pthread.h>
+                  static pthread_once_t a_once = PTHREAD_ONCE_INIT;
+                  static int a;
+                  static void a_init (void) { a = 8647; }
+                ]],
+                [[if (pthread_once (&a_once, a_init)) return 1;
+                  if (a != 8647) return 2;
+                  return 0;
+                ]])],
+             [gl_cv_func_pthread_once_no_lib=yes],
+             [gl_cv_func_pthread_once_no_lib=no],
+             [case "$host_os" in
+                # Guess no on glibc.
+                *-gnu* | gnu*)
+                  gl_cv_func_pthread_once_no_lib="guessing no" ;;
+                # Guess no on FreeBSD.
+                freebsd* | dragonfly* | midnightbsd*)
+                  gl_cv_func_pthread_once_no_lib="guessing no" ;;
+                # Guess yes otherwise.
+                *)
+                  gl_cv_func_pthread_once_no_lib="guessing yes" ;;
+              esac
+             ])
+          ])
+        case "$gl_cv_func_pthread_once_no_lib" in
+          *yes) PTHREAD_ONCE_LIB="$LIBPTHREAD" ;;
+          *)    PTHREAD_ONCE_LIB="$LIBPMULTITHREAD" ;;
+        esac
+        dnl Expected result:
+        dnl PTHREAD_ONCE_LIB is $(LIBPMULTITHREAD) on glibc < 2.34, FreeBSD.
+        dnl PTHREAD_ONCE_LIB is $(LIBPTHREAD) in particular on
+        dnl   musl libc, macOS, NetBSD, Solaris, Cygwin, Haiku, Android.
+      else
+        PTHREAD_ONCE_LIB="$LIBPTHREAD"
+      fi
+    fi
+  fi
+  AC_SUBST([PTHREAD_ONCE_LIB])
+])
diff --git a/gl/m4/pthread-spin.m4 b/gl/m4/pthread-spin.m4
new file mode 100644
index 00000000..aae2fb3b
--- /dev/null
+++ b/gl/m4/pthread-spin.m4
@@ -0,0 +1,72 @@
+# pthread-spin.m4
+# serial 8
+dnl Copyright (C) 2019-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_PTHREAD_SPIN],
+[
+  AC_REQUIRE([gl_PTHREAD_H_PART1])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  if { case "$host_os" in mingw* | windows*) true;; *) false;; esac; } \
+     && test $gl_threads_api = windows; then
+    dnl Choose function names that don't conflict with the mingw-w64 winpthreads
+    dnl library.
+    REPLACE_PTHREAD_SPIN_INIT=1
+    REPLACE_PTHREAD_SPIN_LOCK=1
+    REPLACE_PTHREAD_SPIN_TRYLOCK=1
+    REPLACE_PTHREAD_SPIN_UNLOCK=1
+    REPLACE_PTHREAD_SPIN_DESTROY=1
+  else
+    if test $HAVE_PTHREAD_H = 0 || test $HAVE_PTHREAD_SPINLOCK_T = 0; then
+      HAVE_PTHREAD_SPIN_INIT=0
+      HAVE_PTHREAD_SPIN_LOCK=0
+      HAVE_PTHREAD_SPIN_TRYLOCK=0
+      HAVE_PTHREAD_SPIN_UNLOCK=0
+      HAVE_PTHREAD_SPIN_DESTROY=0
+    else
+      dnl Test whether the gnulib module 'threadlib' is in use.
+      dnl Some packages like Emacs use --avoid=threadlib.
+      dnl Write the symbol in such a way that it does not cause 'aclocal' to pick
+      dnl the threadlib.m4 file that is installed in $PREFIX/share/aclocal/.
+      m4_ifdef([gl_][THREADLIB], [
+        AC_REQUIRE([gl_][THREADLIB])
+        dnl Test whether the functions actually exist.
+        dnl FreeBSD 5.2.1 declares them but does not define them.
+        AC_CACHE_CHECK([for pthread_spin_init],
+          [gl_cv_func_pthread_spin_init_in_LIBMULTITHREAD],
+          [gl_saved_LIBS="$LIBS"
+           LIBS="$LIBS $LIBMULTITHREAD"
+           AC_LINK_IFELSE(
+             [AC_LANG_PROGRAM(
+                [[#include <pthread.h>
+                ]],
+                [[pthread_spinlock_t lock;
+                  return pthread_spin_init (&lock, 0);
+                ]])
+             ],
+             [gl_cv_func_pthread_spin_init_in_LIBMULTITHREAD=yes],
+             [gl_cv_func_pthread_spin_init_in_LIBMULTITHREAD=no])
+           LIBS="$gl_saved_LIBS"
+          ])
+        if test $gl_cv_func_pthread_spin_init_in_LIBMULTITHREAD != yes; then
+          HAVE_PTHREAD_SPIN_INIT=0
+          REPLACE_PTHREAD_SPIN_INIT=1
+          HAVE_PTHREAD_SPIN_LOCK=0
+          REPLACE_PTHREAD_SPIN_LOCK=1
+          HAVE_PTHREAD_SPIN_TRYLOCK=0
+          REPLACE_PTHREAD_SPIN_TRYLOCK=1
+          HAVE_PTHREAD_SPIN_UNLOCK=0
+          REPLACE_PTHREAD_SPIN_UNLOCK=1
+          HAVE_PTHREAD_SPIN_DESTROY=0
+          REPLACE_PTHREAD_SPIN_DESTROY=1
+        fi
+      ], [
+        :
+      ])
+    fi
+  fi
+])
diff --git a/gl/m4/pthread_h.m4 b/gl/m4/pthread_h.m4
new file mode 100644
index 00000000..bb921386
--- /dev/null
+++ b/gl/m4/pthread_h.m4
@@ -0,0 +1,293 @@
+# pthread_h.m4
+# serial 11
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_PTHREAD_H_PART1],
+[
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
+  AC_REQUIRE([gl_PTHREAD_H_DEFAULTS])
+
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_PTHREADLIB])
+
+  gl_CHECK_NEXT_HEADERS([pthread.h])
+  if test $ac_cv_header_pthread_h = yes; then
+    HAVE_PTHREAD_H=1
+    dnl On mingw, if --enable-threads=windows or gl_AVOID_WINPTHREAD is used,
+    dnl ignore the <pthread.h> from the mingw-w64 winpthreads library.
+    m4_ifdef([gl_][THREADLIB], [
+      AC_REQUIRE([gl_][THREADLIB])
+      if { case "$host_os" in mingw* | windows*) true;; *) false;; esac; } \
+         && test $gl_threads_api = windows; then
+        HAVE_PTHREAD_H=0
+      fi
+    ])
+  else
+    HAVE_PTHREAD_H=0
+  fi
+  AC_SUBST([HAVE_PTHREAD_H])
+
+  AC_CHECK_TYPES([pthread_t, pthread_spinlock_t], [], [],
+    [AC_INCLUDES_DEFAULT[
+     #if HAVE_PTHREAD_H
+      #include <pthread.h>
+     #endif]])
+  if test $ac_cv_type_pthread_t != yes; then
+    HAVE_PTHREAD_T=0
+  fi
+  if test $ac_cv_type_pthread_spinlock_t != yes; then
+    HAVE_PTHREAD_SPINLOCK_T=0
+  fi
+])
+
+AC_DEFUN([gl_PTHREAD_H],
+[
+  AC_REQUIRE([gl_PTHREAD_H_PART1])
+
+  dnl Set HAVE_PTHREAD_SPIN_INIT, REPLACE_PTHREAD_SPIN_INIT.
+  gl_PTHREAD_SPIN
+
+  dnl Constants may be defined as C preprocessor macros or as enum items.
+
+  AC_CACHE_CHECK([for PTHREAD_CREATE_DETACHED],
+    [gl_cv_const_PTHREAD_CREATE_DETACHED],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <pthread.h>
+            int x = PTHREAD_CREATE_DETACHED;
+          ]],
+          [[]])],
+       [gl_cv_const_PTHREAD_CREATE_DETACHED=yes],
+       [gl_cv_const_PTHREAD_CREATE_DETACHED=no])
+    ])
+  if test $gl_cv_const_PTHREAD_CREATE_DETACHED != yes; then
+    HAVE_PTHREAD_CREATE_DETACHED=0
+  fi
+
+  AC_CACHE_CHECK([for PTHREAD_MUTEX_RECURSIVE],
+    [gl_cv_const_PTHREAD_MUTEX_RECURSIVE],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <pthread.h>
+            int x = PTHREAD_MUTEX_RECURSIVE;
+          ]],
+          [[]])],
+       [gl_cv_const_PTHREAD_MUTEX_RECURSIVE=yes],
+       [gl_cv_const_PTHREAD_MUTEX_RECURSIVE=no])
+    ])
+  if test $gl_cv_const_PTHREAD_MUTEX_RECURSIVE != yes; then
+    HAVE_PTHREAD_MUTEX_RECURSIVE=0
+  fi
+
+  AC_CACHE_CHECK([for PTHREAD_MUTEX_ROBUST],
+    [gl_cv_const_PTHREAD_MUTEX_ROBUST],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <pthread.h>
+            int x = PTHREAD_MUTEX_ROBUST;
+          ]],
+          [[]])],
+       [gl_cv_const_PTHREAD_MUTEX_ROBUST=yes],
+       [gl_cv_const_PTHREAD_MUTEX_ROBUST=no])
+    ])
+  if test $gl_cv_const_PTHREAD_MUTEX_ROBUST != yes; then
+    HAVE_PTHREAD_MUTEX_ROBUST=0
+  fi
+
+  AC_CACHE_CHECK([for PTHREAD_PROCESS_SHARED],
+    [gl_cv_const_PTHREAD_PROCESS_SHARED],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <pthread.h>
+            int x = PTHREAD_PROCESS_SHARED;
+          ]],
+          [[]])],
+       [gl_cv_const_PTHREAD_PROCESS_SHARED=yes],
+       [gl_cv_const_PTHREAD_PROCESS_SHARED=no])
+    ])
+  if test $gl_cv_const_PTHREAD_PROCESS_SHARED != yes; then
+    HAVE_PTHREAD_PROCESS_SHARED=0
+  fi
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use, if it is not common
+  dnl enough to be declared everywhere.
+  gl_WARN_ON_USE_PREPARE([[#include <pthread.h>
+    ]], [
+    pthread_create pthread_attr_init pthread_attr_getdetachstate
+    pthread_attr_setdetachstate pthread_attr_destroy pthread_self pthread_equal
+    pthread_detach pthread_join pthread_exit
+    pthread_once
+    pthread_mutex_init pthread_mutexattr_init pthread_mutexattr_gettype
+    pthread_mutexattr_settype pthread_mutexattr_getrobust
+    pthread_mutexattr_setrobust pthread_mutexattr_destroy pthread_mutex_lock
+    pthread_mutex_trylock pthread_mutex_timedlock pthread_mutex_unlock
+    pthread_mutex_destroy
+    pthread_rwlock_init pthread_rwlockattr_init pthread_rwlockattr_destroy
+    pthread_rwlock_rdlock pthread_rwlock_wrlock pthread_rwlock_tryrdlock
+    pthread_rwlock_trywrlock pthread_rwlock_timedrdlock
+    pthread_rwlock_timedwrlock pthread_rwlock_unlock pthread_rwlock_destroy
+    pthread_cond_init pthread_condattr_init pthread_condattr_destroy
+    pthread_cond_wait pthread_cond_timedwait pthread_cond_signal
+    pthread_cond_broadcast pthread_cond_destroy
+    pthread_key_create pthread_setspecific pthread_getspecific
+    pthread_key_delete
+    pthread_spin_init pthread_spin_lock pthread_spin_trylock pthread_spin_unlock
+    pthread_spin_destroy])
+
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  dnl For backward compatibility with gnulib versions <= 2019-07.
+  LIB_PTHREAD="$LIBPMULTITHREAD"
+  AC_SUBST([LIB_PTHREAD])
+])
+
+# gl_PTHREAD_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
+AC_DEFUN([gl_PTHREAD_MODULE_INDICATOR],
+[
+  dnl Ensure to expand the default settings once only.
+  gl_PTHREAD_H_REQUIRE_DEFAULTS
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_PTHREAD_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_PTHREAD_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_THREAD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_ONCE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_MUTEX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_RWLOCK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_COND])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_TSS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_SPIN])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTHREAD_MUTEX_TIMEDLOCK])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_PTHREAD_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_PTHREAD_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_PTHREAD_H_DEFAULTS],
+[
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_PTHREAD_T=1;                      AC_SUBST([HAVE_PTHREAD_T])
+  HAVE_PTHREAD_SPINLOCK_T=1;             AC_SUBST([HAVE_PTHREAD_SPINLOCK_T])
+  HAVE_PTHREAD_CREATE_DETACHED=1;        AC_SUBST([HAVE_PTHREAD_CREATE_DETACHED])
+  HAVE_PTHREAD_MUTEX_RECURSIVE=1;        AC_SUBST([HAVE_PTHREAD_MUTEX_RECURSIVE])
+  HAVE_PTHREAD_MUTEX_ROBUST=1;           AC_SUBST([HAVE_PTHREAD_MUTEX_ROBUST])
+  HAVE_PTHREAD_PROCESS_SHARED=1;         AC_SUBST([HAVE_PTHREAD_PROCESS_SHARED])
+  HAVE_PTHREAD_CREATE=1;                 AC_SUBST([HAVE_PTHREAD_CREATE])
+  HAVE_PTHREAD_ATTR_INIT=1;              AC_SUBST([HAVE_PTHREAD_ATTR_INIT])
+  HAVE_PTHREAD_ATTR_GETDETACHSTATE=1;    AC_SUBST([HAVE_PTHREAD_ATTR_GETDETACHSTATE])
+  HAVE_PTHREAD_ATTR_SETDETACHSTATE=1;    AC_SUBST([HAVE_PTHREAD_ATTR_SETDETACHSTATE])
+  HAVE_PTHREAD_ATTR_DESTROY=1;           AC_SUBST([HAVE_PTHREAD_ATTR_DESTROY])
+  HAVE_PTHREAD_SELF=1;                   AC_SUBST([HAVE_PTHREAD_SELF])
+  HAVE_PTHREAD_EQUAL=1;                  AC_SUBST([HAVE_PTHREAD_EQUAL])
+  HAVE_PTHREAD_DETACH=1;                 AC_SUBST([HAVE_PTHREAD_DETACH])
+  HAVE_PTHREAD_JOIN=1;                   AC_SUBST([HAVE_PTHREAD_JOIN])
+  HAVE_PTHREAD_EXIT=1;                   AC_SUBST([HAVE_PTHREAD_EXIT])
+  HAVE_PTHREAD_ONCE=1;                   AC_SUBST([HAVE_PTHREAD_ONCE])
+  HAVE_PTHREAD_MUTEX_INIT=1;             AC_SUBST([HAVE_PTHREAD_MUTEX_INIT])
+  HAVE_PTHREAD_MUTEXATTR_INIT=1;         AC_SUBST([HAVE_PTHREAD_MUTEXATTR_INIT])
+  HAVE_PTHREAD_MUTEXATTR_GETTYPE=1;      AC_SUBST([HAVE_PTHREAD_MUTEXATTR_GETTYPE])
+  HAVE_PTHREAD_MUTEXATTR_SETTYPE=1;      AC_SUBST([HAVE_PTHREAD_MUTEXATTR_SETTYPE])
+  HAVE_PTHREAD_MUTEXATTR_GETROBUST=1;    AC_SUBST([HAVE_PTHREAD_MUTEXATTR_GETROBUST])
+  HAVE_PTHREAD_MUTEXATTR_SETROBUST=1;    AC_SUBST([HAVE_PTHREAD_MUTEXATTR_SETROBUST])
+  HAVE_PTHREAD_MUTEXATTR_DESTROY=1;      AC_SUBST([HAVE_PTHREAD_MUTEXATTR_DESTROY])
+  HAVE_PTHREAD_MUTEX_LOCK=1;             AC_SUBST([HAVE_PTHREAD_MUTEX_LOCK])
+  HAVE_PTHREAD_MUTEX_TRYLOCK=1;          AC_SUBST([HAVE_PTHREAD_MUTEX_TRYLOCK])
+  HAVE_PTHREAD_MUTEX_TIMEDLOCK=1;        AC_SUBST([HAVE_PTHREAD_MUTEX_TIMEDLOCK])
+  HAVE_PTHREAD_MUTEX_UNLOCK=1;           AC_SUBST([HAVE_PTHREAD_MUTEX_UNLOCK])
+  HAVE_PTHREAD_MUTEX_DESTROY=1;          AC_SUBST([HAVE_PTHREAD_MUTEX_DESTROY])
+  HAVE_PTHREAD_RWLOCK_INIT=1;            AC_SUBST([HAVE_PTHREAD_RWLOCK_INIT])
+  HAVE_PTHREAD_RWLOCKATTR_INIT=1;        AC_SUBST([HAVE_PTHREAD_RWLOCKATTR_INIT])
+  HAVE_PTHREAD_RWLOCKATTR_DESTROY=1;     AC_SUBST([HAVE_PTHREAD_RWLOCKATTR_DESTROY])
+  HAVE_PTHREAD_RWLOCK_RDLOCK=1;          AC_SUBST([HAVE_PTHREAD_RWLOCK_RDLOCK])
+  HAVE_PTHREAD_RWLOCK_WRLOCK=1;          AC_SUBST([HAVE_PTHREAD_RWLOCK_WRLOCK])
+  HAVE_PTHREAD_RWLOCK_TRYRDLOCK=1;       AC_SUBST([HAVE_PTHREAD_RWLOCK_TRYRDLOCK])
+  HAVE_PTHREAD_RWLOCK_TRYWRLOCK=1;       AC_SUBST([HAVE_PTHREAD_RWLOCK_TRYWRLOCK])
+  HAVE_PTHREAD_RWLOCK_TIMEDRDLOCK=1;     AC_SUBST([HAVE_PTHREAD_RWLOCK_TIMEDRDLOCK])
+  HAVE_PTHREAD_RWLOCK_TIMEDWRLOCK=1;     AC_SUBST([HAVE_PTHREAD_RWLOCK_TIMEDWRLOCK])
+  HAVE_PTHREAD_RWLOCK_UNLOCK=1;          AC_SUBST([HAVE_PTHREAD_RWLOCK_UNLOCK])
+  HAVE_PTHREAD_RWLOCK_DESTROY=1;         AC_SUBST([HAVE_PTHREAD_RWLOCK_DESTROY])
+  HAVE_PTHREAD_COND_INIT=1;              AC_SUBST([HAVE_PTHREAD_COND_INIT])
+  HAVE_PTHREAD_CONDATTR_INIT=1;          AC_SUBST([HAVE_PTHREAD_CONDATTR_INIT])
+  HAVE_PTHREAD_CONDATTR_DESTROY=1;       AC_SUBST([HAVE_PTHREAD_CONDATTR_DESTROY])
+  HAVE_PTHREAD_COND_WAIT=1;              AC_SUBST([HAVE_PTHREAD_COND_WAIT])
+  HAVE_PTHREAD_COND_TIMEDWAIT=1;         AC_SUBST([HAVE_PTHREAD_COND_TIMEDWAIT])
+  HAVE_PTHREAD_COND_SIGNAL=1;            AC_SUBST([HAVE_PTHREAD_COND_SIGNAL])
+  HAVE_PTHREAD_COND_BROADCAST=1;         AC_SUBST([HAVE_PTHREAD_COND_BROADCAST])
+  HAVE_PTHREAD_COND_DESTROY=1;           AC_SUBST([HAVE_PTHREAD_COND_DESTROY])
+  HAVE_PTHREAD_KEY_CREATE=1;             AC_SUBST([HAVE_PTHREAD_KEY_CREATE])
+  HAVE_PTHREAD_SETSPECIFIC=1;            AC_SUBST([HAVE_PTHREAD_SETSPECIFIC])
+  HAVE_PTHREAD_GETSPECIFIC=1;            AC_SUBST([HAVE_PTHREAD_GETSPECIFIC])
+  HAVE_PTHREAD_KEY_DELETE=1;             AC_SUBST([HAVE_PTHREAD_KEY_DELETE])
+  HAVE_PTHREAD_SPIN_INIT=1;              AC_SUBST([HAVE_PTHREAD_SPIN_INIT])
+  HAVE_PTHREAD_SPIN_LOCK=1;              AC_SUBST([HAVE_PTHREAD_SPIN_LOCK])
+  HAVE_PTHREAD_SPIN_TRYLOCK=1;           AC_SUBST([HAVE_PTHREAD_SPIN_TRYLOCK])
+  HAVE_PTHREAD_SPIN_UNLOCK=1;            AC_SUBST([HAVE_PTHREAD_SPIN_UNLOCK])
+  HAVE_PTHREAD_SPIN_DESTROY=1;           AC_SUBST([HAVE_PTHREAD_SPIN_DESTROY])
+  REPLACE_PTHREAD_CREATE=0;              AC_SUBST([REPLACE_PTHREAD_CREATE])
+  REPLACE_PTHREAD_ATTR_INIT=0;           AC_SUBST([REPLACE_PTHREAD_ATTR_INIT])
+  REPLACE_PTHREAD_ATTR_GETDETACHSTATE=0; AC_SUBST([REPLACE_PTHREAD_ATTR_GETDETACHSTATE])
+  REPLACE_PTHREAD_ATTR_SETDETACHSTATE=0; AC_SUBST([REPLACE_PTHREAD_ATTR_SETDETACHSTATE])
+  REPLACE_PTHREAD_ATTR_DESTROY=0;        AC_SUBST([REPLACE_PTHREAD_ATTR_DESTROY])
+  REPLACE_PTHREAD_SELF=0;                AC_SUBST([REPLACE_PTHREAD_SELF])
+  REPLACE_PTHREAD_EQUAL=0;               AC_SUBST([REPLACE_PTHREAD_EQUAL])
+  REPLACE_PTHREAD_DETACH=0;              AC_SUBST([REPLACE_PTHREAD_DETACH])
+  REPLACE_PTHREAD_JOIN=0;                AC_SUBST([REPLACE_PTHREAD_JOIN])
+  REPLACE_PTHREAD_EXIT=0;                AC_SUBST([REPLACE_PTHREAD_EXIT])
+  REPLACE_PTHREAD_ONCE=0;                AC_SUBST([REPLACE_PTHREAD_ONCE])
+  REPLACE_PTHREAD_MUTEX_INIT=0;          AC_SUBST([REPLACE_PTHREAD_MUTEX_INIT])
+  REPLACE_PTHREAD_MUTEXATTR_INIT=0;      AC_SUBST([REPLACE_PTHREAD_MUTEXATTR_INIT])
+  REPLACE_PTHREAD_MUTEXATTR_GETTYPE=0;   AC_SUBST([REPLACE_PTHREAD_MUTEXATTR_GETTYPE])
+  REPLACE_PTHREAD_MUTEXATTR_SETTYPE=0;   AC_SUBST([REPLACE_PTHREAD_MUTEXATTR_SETTYPE])
+  REPLACE_PTHREAD_MUTEXATTR_GETROBUST=0; AC_SUBST([REPLACE_PTHREAD_MUTEXATTR_GETROBUST])
+  REPLACE_PTHREAD_MUTEXATTR_SETROBUST=0; AC_SUBST([REPLACE_PTHREAD_MUTEXATTR_SETROBUST])
+  REPLACE_PTHREAD_MUTEXATTR_DESTROY=0;   AC_SUBST([REPLACE_PTHREAD_MUTEXATTR_DESTROY])
+  REPLACE_PTHREAD_MUTEX_LOCK=0;          AC_SUBST([REPLACE_PTHREAD_MUTEX_LOCK])
+  REPLACE_PTHREAD_MUTEX_TRYLOCK=0;       AC_SUBST([REPLACE_PTHREAD_MUTEX_TRYLOCK])
+  REPLACE_PTHREAD_MUTEX_TIMEDLOCK=0;     AC_SUBST([REPLACE_PTHREAD_MUTEX_TIMEDLOCK])
+  REPLACE_PTHREAD_MUTEX_UNLOCK=0;        AC_SUBST([REPLACE_PTHREAD_MUTEX_UNLOCK])
+  REPLACE_PTHREAD_MUTEX_DESTROY=0;       AC_SUBST([REPLACE_PTHREAD_MUTEX_DESTROY])
+  REPLACE_PTHREAD_RWLOCK_INIT=0;         AC_SUBST([REPLACE_PTHREAD_RWLOCK_INIT])
+  REPLACE_PTHREAD_RWLOCKATTR_INIT=0;     AC_SUBST([REPLACE_PTHREAD_RWLOCKATTR_INIT])
+  REPLACE_PTHREAD_RWLOCKATTR_DESTROY=0;  AC_SUBST([REPLACE_PTHREAD_RWLOCKATTR_DESTROY])
+  REPLACE_PTHREAD_RWLOCK_RDLOCK=0;       AC_SUBST([REPLACE_PTHREAD_RWLOCK_RDLOCK])
+  REPLACE_PTHREAD_RWLOCK_WRLOCK=0;       AC_SUBST([REPLACE_PTHREAD_RWLOCK_WRLOCK])
+  REPLACE_PTHREAD_RWLOCK_TRYRDLOCK=0;    AC_SUBST([REPLACE_PTHREAD_RWLOCK_TRYRDLOCK])
+  REPLACE_PTHREAD_RWLOCK_TRYWRLOCK=0;    AC_SUBST([REPLACE_PTHREAD_RWLOCK_TRYWRLOCK])
+  REPLACE_PTHREAD_RWLOCK_TIMEDRDLOCK=0;  AC_SUBST([REPLACE_PTHREAD_RWLOCK_TIMEDRDLOCK])
+  REPLACE_PTHREAD_RWLOCK_TIMEDWRLOCK=0;  AC_SUBST([REPLACE_PTHREAD_RWLOCK_TIMEDWRLOCK])
+  REPLACE_PTHREAD_RWLOCK_UNLOCK=0;       AC_SUBST([REPLACE_PTHREAD_RWLOCK_UNLOCK])
+  REPLACE_PTHREAD_RWLOCK_DESTROY=0;      AC_SUBST([REPLACE_PTHREAD_RWLOCK_DESTROY])
+  REPLACE_PTHREAD_COND_INIT=0;           AC_SUBST([REPLACE_PTHREAD_COND_INIT])
+  REPLACE_PTHREAD_CONDATTR_INIT=0;       AC_SUBST([REPLACE_PTHREAD_CONDATTR_INIT])
+  REPLACE_PTHREAD_CONDATTR_DESTROY=0;    AC_SUBST([REPLACE_PTHREAD_CONDATTR_DESTROY])
+  REPLACE_PTHREAD_COND_WAIT=0;           AC_SUBST([REPLACE_PTHREAD_COND_WAIT])
+  REPLACE_PTHREAD_COND_TIMEDWAIT=0;      AC_SUBST([REPLACE_PTHREAD_COND_TIMEDWAIT])
+  REPLACE_PTHREAD_COND_SIGNAL=0;         AC_SUBST([REPLACE_PTHREAD_COND_SIGNAL])
+  REPLACE_PTHREAD_COND_BROADCAST=0;      AC_SUBST([REPLACE_PTHREAD_COND_BROADCAST])
+  REPLACE_PTHREAD_COND_DESTROY=0;        AC_SUBST([REPLACE_PTHREAD_COND_DESTROY])
+  REPLACE_PTHREAD_KEY_CREATE=0;          AC_SUBST([REPLACE_PTHREAD_KEY_CREATE])
+  REPLACE_PTHREAD_SETSPECIFIC=0;         AC_SUBST([REPLACE_PTHREAD_SETSPECIFIC])
+  REPLACE_PTHREAD_GETSPECIFIC=0;         AC_SUBST([REPLACE_PTHREAD_GETSPECIFIC])
+  REPLACE_PTHREAD_KEY_DELETE=0;          AC_SUBST([REPLACE_PTHREAD_KEY_DELETE])
+  REPLACE_PTHREAD_SPIN_INIT=0;           AC_SUBST([REPLACE_PTHREAD_SPIN_INIT])
+  REPLACE_PTHREAD_SPIN_LOCK=0;           AC_SUBST([REPLACE_PTHREAD_SPIN_LOCK])
+  REPLACE_PTHREAD_SPIN_TRYLOCK=0;        AC_SUBST([REPLACE_PTHREAD_SPIN_TRYLOCK])
+  REPLACE_PTHREAD_SPIN_UNLOCK=0;         AC_SUBST([REPLACE_PTHREAD_SPIN_UNLOCK])
+  REPLACE_PTHREAD_SPIN_DESTROY=0;        AC_SUBST([REPLACE_PTHREAD_SPIN_DESTROY])
+])
diff --git a/gl/m4/pthread_rwlock_rdlock.m4 b/gl/m4/pthread_rwlock_rdlock.m4
index ae6a8853..aec9f076 100644
--- a/gl/m4/pthread_rwlock_rdlock.m4
+++ b/gl/m4/pthread_rwlock_rdlock.m4
@@ -1,8 +1,10 @@
-# pthread_rwlock_rdlock.m4 serial 4
-dnl Copyright (C) 2017-2023 Free Software Foundation, Inc.
+# pthread_rwlock_rdlock.m4
+# serial 8
+dnl Copyright (C) 2017-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 dnl Inspired by
@@ -34,11 +36,11 @@ dnl https://sourceware.org/bugzilla/show_bug.cgi?id=13701
 dnl https://bugzilla.redhat.com/show_bug.cgi?id=1410052
 AC_DEFUN([gl_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER],
 [
-  AC_REQUIRE([gl_THREADLIB_EARLY])
+  AC_REQUIRE([gl_THREADLIB])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CACHE_CHECK([whether pthread_rwlock_rdlock prefers a writer to a reader],
     [gl_cv_pthread_rwlock_rdlock_prefer_writer],
-    [save_LIBS="$LIBS"
+    [saved_LIBS="$LIBS"
      LIBS="$LIBS $LIBMULTITHREAD"
      AC_RUN_IFELSE(
        [AC_LANG_SOURCE([[
@@ -156,25 +158,25 @@ main ()
        [gl_cv_pthread_rwlock_rdlock_prefer_writer=yes],
        [gl_cv_pthread_rwlock_rdlock_prefer_writer=no],
        [case "$host_os" in
-                         # Guess no on glibc systems.
-          *-gnu* | gnu*) gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
-                         # Guess no on musl systems.
-          *-musl*)       gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
-                         # Guess no on bionic systems.
-          *-android*)    gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
-                         # Guess yes on native Windows with the mingw-w64 winpthreads library.
-                         # Guess no on native Windows with the gnulib windows-rwlock module.
-          mingw*)        if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
-                           gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing yes"
-                         else
-                           gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no"
-                         fi
-                         ;;
-                         # If we don't know, obey --enable-cross-guesses.
-          *)             gl_cv_pthread_rwlock_rdlock_prefer_writer="$gl_cross_guess_normal" ;;
+                              # Guess no on glibc systems.
+          *-gnu* | gnu*)      gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
+                              # Guess no on musl systems.
+          *-musl* | midipix*) gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
+                              # Guess no on bionic systems.
+          *-android*)         gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no" ;;
+                              # Guess yes on native Windows with the mingw-w64 winpthreads library.
+                              # Guess no on native Windows with the gnulib windows-rwlock module.
+          mingw* | windows*)  if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
+                                gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing yes"
+                              else
+                                gl_cv_pthread_rwlock_rdlock_prefer_writer="guessing no"
+                              fi
+                              ;;
+                              # If we don't know, obey --enable-cross-guesses.
+          *)                  gl_cv_pthread_rwlock_rdlock_prefer_writer="$gl_cross_guess_normal" ;;
          esac
        ])
-     LIBS="$save_LIBS"
+     LIBS="$saved_LIBS"
     ])
   case "$gl_cv_pthread_rwlock_rdlock_prefer_writer" in
     *yes)
diff --git a/gl/m4/realloc.m4 b/gl/m4/realloc.m4
index d22138fc..67c1476b 100644
--- a/gl/m4/realloc.m4
+++ b/gl/m4/realloc.m4
@@ -1,52 +1,22 @@
-# realloc.m4 serial 26
-dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
+# realloc.m4
+# serial 39.1
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# This is adapted with modifications from upstream Autoconf here:
-# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=v2.70#n1455
-AC_DEFUN([_AC_FUNC_REALLOC_IF],
+# An an experimental option, the user can request a sanitized realloc()
+# implementation, i.e. one that aborts upon undefined behaviour,
+# by setting
+#   gl_cv_func_realloc_sanitize=yes
+# at configure time.
+AC_DEFUN([gl_FUNC_REALLOC_SANITIZED],
 [
-  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
-  AC_CACHE_CHECK([whether realloc (0, 0) returns nonnull],
-    [ac_cv_func_realloc_0_nonnull],
-    [AC_RUN_IFELSE(
-       [AC_LANG_PROGRAM(
-          [[#include <stdlib.h>
-          ]],
-          [[void *p = realloc (0, 0);
-            int result = !p;
-            free (p);
-            return result;]])
-       ],
-       [ac_cv_func_realloc_0_nonnull=yes],
-       [ac_cv_func_realloc_0_nonnull=no],
-       [case "$host_os" in
-          # Guess yes on platforms where we know the result.
-          *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
-          | gnu* | *-musl* | midnightbsd* \
-          | hpux* | solaris* | cygwin* | mingw* | msys* )
-            ac_cv_func_realloc_0_nonnull="guessing yes" ;;
-          # If we don't know, obey --enable-cross-guesses.
-          *) ac_cv_func_realloc_0_nonnull="$gl_cross_guess_normal" ;;
-        esac
-       ])
-    ])
-  AS_CASE([$ac_cv_func_realloc_0_nonnull], [*yes], [$1], [$2])
-])# AC_FUNC_REALLOC
-
-# gl_FUNC_REALLOC_GNU
-# -------------------
-# Replace realloc if it is not compatible with GNU libc.
-AC_DEFUN([gl_FUNC_REALLOC_GNU],
-[
-  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
-  AC_REQUIRE([gl_FUNC_REALLOC_POSIX])
-  if test $REPLACE_REALLOC_FOR_REALLOC_GNU = 0; then
-    _AC_FUNC_REALLOC_IF([], [REPLACE_REALLOC_FOR_REALLOC_GNU=1])
-  fi
-])# gl_FUNC_REALLOC_GNU
+  AC_CACHE_CHECK([whether realloc should abort upon undefined behaviour],
+    [gl_cv_func_realloc_sanitize],
+    [test -n "$gl_cv_func_realloc_sanitize" || gl_cv_func_realloc_sanitize=no])
+])
 
 # gl_FUNC_REALLOC_POSIX
 # ---------------------
@@ -57,7 +27,100 @@ AC_DEFUN([gl_FUNC_REALLOC_POSIX],
 [
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
-  if test $REPLACE_MALLOC_FOR_MALLOC_POSIX = 1; then
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CACHE_CHECK([whether realloc sets errno on failure],
+    [gl_cv_func_realloc_posix],
+    [
+      dnl FreeBSD 15.0 realloc() does not set errno when asked for more than
+      dnl 0x7000000000000000 bytes.
+      case "$host_os" in
+        darwin* | freebsd* | dragonfly* | midnightbsd* | netbsd* | openbsd*)
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE(
+               [[#include <errno.h>
+                 #include <stdlib.h>
+                 int main (int argc, char **argv)
+                 {
+                   void *p;
+                   errno = 1729;
+                   p = realloc (malloc (1), (size_t)(-1) / 100 * 49);
+                   return (!p && errno == 1729);
+                 }
+               ]])
+            ],
+            [gl_cv_func_realloc_posix=yes],
+            [gl_cv_func_realloc_posix=no],
+            [case "$host_os" in
+               freebsd*) gl_cv_func_realloc_posix="guessing no" ;;
+               *)        gl_cv_func_realloc_posix="guessing yes" ;;
+             esac
+            ])
+          ;;
+        *)
+          gl_cv_func_realloc_posix="$gl_cv_func_malloc_posix"
+          ;;
+      esac
+    ])
+  case "$gl_cv_func_realloc_posix" in
+    *yes)
+      AC_DEFINE([HAVE_REALLOC_POSIX], [1],
+        [Define if realloc sets errno on allocation failure.])
+      ;;
+    *)
+      REPLACE_REALLOC_FOR_REALLOC_POSIX=1
+      ;;
+  esac
+  AC_REQUIRE([gl_FUNC_REALLOC_SANITIZED])
+  if test "$gl_cv_func_realloc_sanitize" != no; then
     REPLACE_REALLOC_FOR_REALLOC_POSIX=1
+    AC_DEFINE([NEED_SANITIZED_REALLOC], [1],
+      [Define to 1 if realloc should abort upon undefined behaviour.])
   fi
 ])
+
+# gl_FUNC_REALLOC_0_NONNULL
+# -------------------------
+# Replace realloc if realloc (..., 0) returns null.
+# Modules that use this macro directly or indirectly should depend
+# on extensions-aix, so that _LINUX_SOURCE_COMPAT gets defined
+# before this macro gets invoked.  This helps if !(__VEC__ || __AIXVEC),
+# and doesn't hurt otherwise.
+AC_DEFUN([gl_FUNC_REALLOC_0_NONNULL],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
+  AC_REQUIRE([gl_FUNC_REALLOC_POSIX])
+  AC_CACHE_CHECK([whether realloc (..., 0) returns nonnull],
+    [gl_cv_func_realloc_0_nonnull],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stdlib.h>
+            /* Use prealloc to test; "volatile" prevents the compiler
+               from optimizing the realloc call away.  */
+            void *(*volatile prealloc) (void *, size_t) = realloc;]],
+          [[void *p = prealloc (0, 0);
+            int result = !p;
+            p = prealloc (p, 0);
+            result |= !p;
+            free (p);
+            return result;]])],
+       [gl_cv_func_realloc_0_nonnull=yes],
+       [gl_cv_func_realloc_0_nonnull=no],
+       [AS_CASE([$host_os],
+          [# Guess yes on platforms where we know the result.
+           freebsd* | netbsd* | openbsd* | darwin* | bitrig* \
+           | *-musl* | midipix* | midnightbsd* \
+           | hpux* | solaris* | cygwin*],
+            [gl_cv_func_realloc_0_nonnull="guessing yes"],
+          [# Guess as follows if we don't know.
+           gl_cv_func_realloc_0_nonnull=$gl_cross_guess_normal])])])
+  AS_CASE([$gl_cv_func_realloc_0_nonnull],
+    [*yes],
+      [AC_DEFINE([HAVE_REALLOC_0_NONNULL], [1],
+         [Define to 1 if realloc (..., 0) returns nonnull.])],
+    [AS_CASE([$gl_cv_func_realloc_sanitize,$gl_cv_malloc_ptrdiff,$gl_cv_func_malloc_posix,$host],
+       [yes,*,*,* | *,no,*,* | *,*,*no,* | *,*,*,aarch64c-*-freebsd*],
+         [REPLACE_REALLOC_FOR_REALLOC_POSIX=1],
+       [# Optimize for common case of glibc 2.1.1+ and compatibles.
+        REPLACE_REALLOC_FOR_REALLOC_POSIX=2])])
+])
diff --git a/gl/m4/reallocarray.m4 b/gl/m4/reallocarray.m4
index 1607b7a9..3970d9e1 100644
--- a/gl/m4/reallocarray.m4
+++ b/gl/m4/reallocarray.m4
@@ -1,8 +1,10 @@
-# reallocarray.m4 serial 3
-dnl Copyright (C) 2017-2023 Free Software Foundation, Inc.
+# reallocarray.m4
+# serial 7
+dnl Copyright (C) 2017-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_REALLOCARRAY],
 [
@@ -11,11 +13,21 @@ AC_DEFUN([gl_FUNC_REALLOCARRAY],
 
   AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
   AC_REQUIRE([gl_CHECK_MALLOC_PTRDIFF])
-  AC_CHECK_FUNCS([reallocarray])
+  AC_REQUIRE([gl_FUNC_REALLOC_0_NONNULL])
+  gl_CHECK_FUNCS_ANDROID([reallocarray], [[#include <stdlib.h>]])
   if test "$ac_cv_func_reallocarray" = no; then
     HAVE_REALLOCARRAY=0
-  elif test "$gl_cv_malloc_ptrdiff" = no; then
-    REPLACE_REALLOCARRAY=1
+    case "$gl_cv_onwards_func_reallocarray" in
+      future*) REPLACE_REALLOCARRAY=1 ;;
+    esac
+  else
+    if test "$gl_cv_malloc_ptrdiff" = no; then
+      REPLACE_REALLOCARRAY=1
+    fi
+    case "$gl_cv_func_realloc_0_nonnull" in
+      *yes) ;;
+      *) REPLACE_REALLOCARRAY=1 ;;
+    esac
   fi
 ])
 
diff --git a/gl/m4/regex.m4 b/gl/m4/regex.m4
index c89a1432..49a8059f 100644
--- a/gl/m4/regex.m4
+++ b/gl/m4/regex.m4
@@ -1,10 +1,10 @@
-# serial 73
-
-# Copyright (C) 1996-2001, 2003-2023 Free Software Foundation, Inc.
-#
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# regex.m4
+# serial 81
+dnl Copyright (C) 1996-2001, 2003-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Initially derived from code in GNU grep.
 dnl Mostly written by Jim Meyering.
@@ -15,7 +15,7 @@ AC_DEFUN([gl_REGEX],
 [
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_ARG_WITH([included-regex],
-    [AS_HELP_STRING([--without-included-regex],
+    [AS_HELP_STRING([[--without-included-regex]],
                     [don't compile regex; this is the default on systems
                      with recent-enough versions of the GNU C Library
                      (use with caution on other systems).])])
@@ -40,19 +40,24 @@ AC_DEFUN([gl_REGEX],
             #include <limits.h>
             #include <string.h>
 
-            #if defined M_CHECK_ACTION || HAVE_DECL_ALARM
-            # include <signal.h>
-            # include <unistd.h>
+            #if HAVE_MALLOC_H
+            # include <malloc.h> /* defines M_CHECK_ACTION on glibc */
             #endif
 
-            #if HAVE_MALLOC_H
-            # include <malloc.h>
+            #if defined __HAIKU__ || defined M_CHECK_ACTION || HAVE_DECL_ALARM
+            # include <signal.h>
+            # include <unistd.h>
             #endif
 
-            #ifdef M_CHECK_ACTION
+            #if defined __HAIKU__ || defined M_CHECK_ACTION
             /* Exit with distinguishable exit code.  */
             static void sigabrt_no_core (int sig) { raise (SIGTERM); }
             #endif
+
+            /* There is no need to check whether RE_SYNTAX_EMACS is
+               (RE_CHAR_CLASSES | RE_INTERVALS), corresponding to
+               Emacs 21 (2001) and later, because Gnulib's lib/regex.h
+               is always used and has this value.  */
           ]],
           [[int result = 0;
             static struct re_pattern_buffer regex;
@@ -68,6 +73,9 @@ AC_DEFUN([gl_REGEX],
             signal (SIGALRM, SIG_DFL);
             alarm (2);
 #endif
+#ifdef __HAIKU__
+            signal (SIGABRT, sigabrt_no_core);
+#endif
 #ifdef M_CHECK_ACTION
             signal (SIGABRT, sigabrt_no_core);
             mallopt (M_CHECK_ACTION, 2);
@@ -327,10 +335,10 @@ AC_DEFUN([gl_REGEX],
         [gl_cv_func_re_compile_pattern_working=yes],
         [gl_cv_func_re_compile_pattern_working=no],
         [case "$host_os" in
-                   # Guess no on native Windows.
-           mingw*) gl_cv_func_re_compile_pattern_working="guessing no" ;;
-                   # Otherwise obey --enable-cross-guesses.
-           *)      gl_cv_func_re_compile_pattern_working="$gl_cross_guess_normal" ;;
+                              # Guess no on native Windows.
+           mingw* | windows*) gl_cv_func_re_compile_pattern_working="guessing no" ;;
+                              # Otherwise obey --enable-cross-guesses.
+           *)                 gl_cv_func_re_compile_pattern_working="$gl_cross_guess_normal" ;;
          esac
         ])
       ])
@@ -389,7 +397,6 @@ AC_DEFUN([gl_PREREQ_REGEX],
   AC_REQUIRE([AC_C_INLINE])
   AC_REQUIRE([AC_C_RESTRICT])
   AC_REQUIRE([AC_TYPE_MBSTATE_T])
-  AC_REQUIRE([gl_EEMALLOC])
   AC_CHECK_HEADERS([libintl.h])
   AC_CHECK_FUNCS_ONCE([isblank iswctype])
   AC_CHECK_DECLS([isblank], [], [], [[#include <ctype.h>]])
diff --git a/gl/m4/sched_h.m4 b/gl/m4/sched_h.m4
new file mode 100644
index 00000000..1ffd465f
--- /dev/null
+++ b/gl/m4/sched_h.m4
@@ -0,0 +1,102 @@
+# sched_h.m4
+# serial 16
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl Written by Bruno Haible.
+
+AC_DEFUN_ONCE([gl_SCHED_H],
+[
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
+  AC_REQUIRE([gl_SCHED_H_DEFAULTS])
+
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  AC_REQUIRE([gl_CHECK_HEADER_SYS_CDEFS_H])
+
+  AC_CHECK_HEADERS([sched.h], [], [],
+    [[#if HAVE_SYS_CDEFS_H
+       #include <sys/cdefs.h>
+      #endif
+    ]])
+  gl_NEXT_HEADERS([sched.h])
+
+  if test "$ac_cv_header_sched_h" = yes; then
+    HAVE_SCHED_H=1
+  else
+    HAVE_SCHED_H=0
+  fi
+  AC_SUBST([HAVE_SCHED_H])
+
+  if test "$HAVE_SCHED_H" = 1; then
+    AC_CHECK_TYPE([struct sched_param],
+      [HAVE_STRUCT_SCHED_PARAM=1], [HAVE_STRUCT_SCHED_PARAM=0],
+      [[#if HAVE_SYS_CDEFS_H
+         #include <sys/cdefs.h>
+        #endif
+        #include <sched.h>
+      ]])
+  else
+    HAVE_STRUCT_SCHED_PARAM=0
+    case "$host_os" in
+      os2*)
+        dnl On OS/2 kLIBC, struct sched_param is in spawn.h.
+        AC_CHECK_TYPE([struct sched_param],
+          [HAVE_STRUCT_SCHED_PARAM=1], [],
+          [#include <spawn.h>])
+        ;;
+      vms)
+        dnl On OpenVMS 7.2 or newer, struct sched_param is in pthread.h.
+        AC_CHECK_TYPE([struct sched_param],
+          [HAVE_STRUCT_SCHED_PARAM=1], [],
+          [#include <pthread.h>])
+        ;;
+    esac
+  fi
+  AC_SUBST([HAVE_STRUCT_SCHED_PARAM])
+
+  dnl Ensure the type pid_t gets defined.
+  AC_REQUIRE([AC_TYPE_PID_T])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use, if it is not common
+  dnl enough to be declared everywhere.
+  gl_WARN_ON_USE_PREPARE([[#include <sched.h>
+    ]], [sched_yield])
+])
+
+# gl_SCHED_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
+AC_DEFUN([gl_SCHED_MODULE_INDICATOR],
+[
+  dnl Ensure to expand the default settings once only.
+  gl_SCHED_H_REQUIRE_DEFAULTS
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_SCHED_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_SCHED_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SCHED_YIELD])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_SCHED_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_SCHED_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_SCHED_H_DEFAULTS],
+[
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_SCHED_YIELD=1;    AC_SUBST([HAVE_SCHED_YIELD])
+  REPLACE_SCHED_YIELD=0; AC_SUBST([REPLACE_SCHED_YIELD])
+])
diff --git a/gl/m4/servent.m4 b/gl/m4/servent.m4
index 0f35b8b8..ba6ebd1d 100644
--- a/gl/m4/servent.m4
+++ b/gl/m4/servent.m4
@@ -1,8 +1,10 @@
-# servent.m4 serial 4
-dnl Copyright (C) 2008, 2010-2023 Free Software Foundation, Inc.
+# servent.m4
+# serial 5
+dnl Copyright (C) 2008, 2010-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_SERVENT],
 [
@@ -28,7 +30,7 @@ AC_DEFUN([gl_SERVENT],
       AC_CACHE_CHECK([for getservbyname in winsock2.h and -lws2_32],
         [gl_cv_w32_getservbyname],
         [gl_cv_w32_getservbyname=no
-         gl_save_LIBS="$LIBS"
+         gl_saved_LIBS="$LIBS"
          LIBS="$LIBS -lws2_32"
          AC_LINK_IFELSE(
            [AC_LANG_PROGRAM(
@@ -40,7 +42,7 @@ AC_DEFUN([gl_SERVENT],
               ]],
               [[getservbyname(NULL,NULL);]])],
            [gl_cv_w32_getservbyname=yes])
-         LIBS="$gl_save_LIBS"
+         LIBS="$gl_saved_LIBS"
         ])
       if test "$gl_cv_w32_getservbyname" = "yes"; then
         SERVENT_LIB="-lws2_32"
diff --git a/gl/m4/setenv.m4 b/gl/m4/setenv.m4
index 16f9eb55..727e35af 100644
--- a/gl/m4/setenv.m4
+++ b/gl/m4/setenv.m4
@@ -1,8 +1,10 @@
-# setenv.m4 serial 30
-dnl Copyright (C) 2001-2004, 2006-2023 Free Software Foundation, Inc.
+# setenv.m4
+# serial 35
+dnl Copyright (C) 2001-2004, 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_SETENV],
 [
@@ -35,12 +37,12 @@ AC_DEFUN([gl_FUNC_SETENV],
       ]])],
       [gl_cv_func_setenv_works=yes], [gl_cv_func_setenv_works=no],
       [case "$host_os" in
-                        # Guess yes on glibc systems.
-         *-gnu* | gnu*) gl_cv_func_setenv_works="guessing yes" ;;
-                        # Guess yes on musl systems.
-         *-musl*)       gl_cv_func_setenv_works="guessing yes" ;;
-                        # If we don't know, obey --enable-cross-guesses.
-         *)             gl_cv_func_setenv_works="$gl_cross_guess_normal" ;;
+                             # Guess yes on glibc systems.
+         *-gnu* | gnu*)      gl_cv_func_setenv_works="guessing yes" ;;
+                             # Guess yes on musl systems.
+         *-musl* | midipix*) gl_cv_func_setenv_works="guessing yes" ;;
+                             # If we don't know, obey --enable-cross-guesses.
+         *)                  gl_cv_func_setenv_works="$gl_cross_guess_normal" ;;
        esac
       ])])
     case "$gl_cv_func_setenv_works" in
@@ -151,11 +153,11 @@ int unsetenv (const char *name);
 # Prerequisites of lib/setenv.c.
 AC_DEFUN([gl_PREREQ_SETENV],
 [
-  AC_REQUIRE([AC_FUNC_ALLOCA])
   AC_REQUIRE([gl_ENVIRON])
   AC_CHECK_HEADERS_ONCE([unistd.h])
   AC_CHECK_HEADERS([search.h])
-  AC_CHECK_FUNCS([tsearch])
+  AC_CHECK_DECLS_ONCE([_putenv])
+  gl_CHECK_FUNCS_ANDROID([tsearch], [[#include <search.h>]])
 ])
 
 # Prerequisites of lib/unsetenv.c.
@@ -163,4 +165,5 @@ AC_DEFUN([gl_PREREQ_UNSETENV],
 [
   AC_REQUIRE([gl_ENVIRON])
   AC_CHECK_HEADERS_ONCE([unistd.h])
+  AC_CHECK_DECLS_ONCE([_putenv])
 ])
diff --git a/gl/m4/setlocale_null.m4 b/gl/m4/setlocale_null.m4
index 032119d0..3c8b693e 100644
--- a/gl/m4/setlocale_null.m4
+++ b/gl/m4/setlocale_null.m4
@@ -1,10 +1,12 @@
-# setlocale_null.m4 serial 5
-dnl Copyright (C) 2019-2023 Free Software Foundation, Inc.
+# setlocale_null.m4
+# serial 10
+dnl Copyright (C) 2019-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-AC_DEFUN([gl_FUNC_SETLOCALE_NULL],
+AC_DEFUN_ONCE([gl_FUNC_SETLOCALE_NULL],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([gl_PTHREADLIB])
@@ -13,11 +15,25 @@ AC_DEFUN([gl_FUNC_SETLOCALE_NULL],
   AC_CACHE_CHECK([whether setlocale (LC_ALL, NULL) is multithread-safe],
     [gl_cv_func_setlocale_null_all_mtsafe],
     [case "$host_os" in
-       # Guess no on musl libc, macOS, FreeBSD, NetBSD, OpenBSD, AIX, Haiku, Cygwin.
-       *-musl* | darwin* | freebsd* | midnightbsd* | netbsd* | openbsd* | aix* | haiku* | cygwin*)
+       # Guess no on musl libc, macOS, FreeBSD, NetBSD, OpenBSD, AIX, Haiku.
+       *-musl* | midipix* | darwin* | freebsd* | midnightbsd* | netbsd* | openbsd* | aix* | haiku*)
          gl_cv_func_setlocale_null_all_mtsafe=no ;;
+       # Guess no on Cygwin < 3.4.6.
+       cygwin*)
+         AC_EGREP_CPP([Lucky user],
+           [
+#if defined __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED >= CYGWIN_VERSION_DLL_MAKE_COMBINED (3004, 6)
+  Lucky user
+ #endif
+#endif
+          ],
+          [gl_cv_func_setlocale_null_all_mtsafe=yes],
+          [gl_cv_func_setlocale_null_all_mtsafe=no])
+        ;;
        # Guess yes on glibc, HP-UX, IRIX, Solaris, native Windows.
-       *-gnu* | gnu* | hpux* | irix* | solaris* | mingw*)
+       *-gnu* | gnu* | hpux* | irix* | solaris* | mingw* | windows*)
          gl_cv_func_setlocale_null_all_mtsafe=yes ;;
        # If we don't know, obey --enable-cross-guesses.
        *)
@@ -26,7 +42,7 @@ AC_DEFUN([gl_FUNC_SETLOCALE_NULL],
     ])
   dnl On platforms without multithreading, there is no issue.
   case "$host_os" in
-    mingw*) ;;
+    mingw* | windows*) ;;
     *)
       if test $gl_pthread_api = no && test $ac_cv_header_threads_h = no; then
         gl_cv_func_setlocale_null_all_mtsafe="trivially yes"
@@ -48,7 +64,7 @@ AC_DEFUN([gl_FUNC_SETLOCALE_NULL],
        openbsd* | aix*)
          gl_cv_func_setlocale_null_one_mtsafe=no ;;
        # Guess yes on glibc, musl libc, macOS, FreeBSD, NetBSD, HP-UX, IRIX, Solaris, Haiku, Cygwin, native Windows.
-       *-gnu* | gnu* | *-musl* | darwin* | freebsd* | midnightbsd* | netbsd* | hpux* | irix* | solaris* | haiku* | cygwin* | mingw*)
+       *-gnu* | gnu* | *-musl* | midipix* | darwin* | freebsd* | midnightbsd* | netbsd* | hpux* | irix* | solaris* | haiku* | cygwin* | mingw* | windows*)
          gl_cv_func_setlocale_null_one_mtsafe=yes ;;
        # If we don't know, obey --enable-cross-guesses.
        *)
@@ -57,7 +73,7 @@ AC_DEFUN([gl_FUNC_SETLOCALE_NULL],
     ])
   dnl On platforms without multithreading, there is no issue.
   case "$host_os" in
-    mingw*) ;;
+    mingw* | windows*) ;;
     *)
       if test $gl_pthread_api = no && test $ac_cv_header_threads_h = no; then
         gl_cv_func_setlocale_null_one_mtsafe="trivially yes"
@@ -74,20 +90,25 @@ AC_DEFUN([gl_FUNC_SETLOCALE_NULL],
   dnl Determine link dependencies of lib/setlocale_null.c and lib/setlocale-lock.c.
   if test $SETLOCALE_NULL_ALL_MTSAFE = 0 || test $SETLOCALE_NULL_ONE_MTSAFE = 0; then
     case "$host_os" in
-      mingw*) LIB_SETLOCALE_NULL= ;;
+      mingw* | windows*)
+        SETLOCALE_NULL_LIB=
+        ;;
       *)
         gl_WEAK_SYMBOLS
         case "$gl_cv_have_weak" in
-          *yes) LIB_SETLOCALE_NULL= ;;
-          *)    LIB_SETLOCALE_NULL="$LIBPTHREAD" ;;
+          *yes) SETLOCALE_NULL_LIB= ;;
+          *)    SETLOCALE_NULL_LIB="$LIBPTHREAD" ;;
         esac
         ;;
     esac
   else
-    LIB_SETLOCALE_NULL=
+    SETLOCALE_NULL_LIB=
   fi
-  dnl LIB_SETLOCALE_NULL is expected to be '-pthread' or '-lpthread' on AIX
+  dnl SETLOCALE_NULL_LIB is expected to be '-pthread' or '-lpthread' on AIX
   dnl with gcc or xlc, and empty otherwise.
+  AC_SUBST([SETLOCALE_NULL_LIB])
+  dnl For backward compatibility.
+  LIB_SETLOCALE_NULL="$SETLOCALE_NULL_LIB"
   AC_SUBST([LIB_SETLOCALE_NULL])
 ])
 
diff --git a/gl/m4/sha256.m4 b/gl/m4/sha256.m4
index 4d1d1dda..30e8deeb 100644
--- a/gl/m4/sha256.m4
+++ b/gl/m4/sha256.m4
@@ -1,8 +1,10 @@
-# sha256.m4 serial 8
-dnl Copyright (C) 2005, 2008-2023 Free Software Foundation, Inc.
+# sha256.m4
+# serial 8
+dnl Copyright (C) 2005, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_SHA256],
 [
diff --git a/gl/m4/size_max.m4 b/gl/m4/size_max.m4
index 0763366d..b0460d45 100644
--- a/gl/m4/size_max.m4
+++ b/gl/m4/size_max.m4
@@ -1,8 +1,10 @@
-# size_max.m4 serial 12
-dnl Copyright (C) 2003, 2005-2006, 2008-2023 Free Software Foundation, Inc.
+# size_max.m4
+# serial 12
+dnl Copyright (C) 2003, 2005-2006, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 
diff --git a/gl/m4/snprintf.m4 b/gl/m4/snprintf.m4
index 4b5fbdbf..2c50cee9 100644
--- a/gl/m4/snprintf.m4
+++ b/gl/m4/snprintf.m4
@@ -1,8 +1,10 @@
-# snprintf.m4 serial 7
-dnl Copyright (C) 2002-2004, 2007-2023 Free Software Foundation, Inc.
+# snprintf.m4
+# serial 7
+dnl Copyright (C) 2002-2004, 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Libintl 0.17 will replace snprintf only if it does not support %1$s,
 dnl but defers to any gnulib snprintf replacements.  Therefore, gnulib
diff --git a/gl/m4/socketlib.m4 b/gl/m4/socketlib.m4
index a556af1e..e3509f81 100644
--- a/gl/m4/socketlib.m4
+++ b/gl/m4/socketlib.m4
@@ -1,8 +1,10 @@
-# socketlib.m4 serial 3
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# socketlib.m4
+# serial 4
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl gl_SOCKETLIB
 dnl Determines the library to use for socket functions.
@@ -18,7 +20,7 @@ AC_DEFUN([gl_SOCKETLIB],
     dnl defined through -lws2_32), we need to call it.
     AC_CACHE_CHECK([for WSAStartup],
       [gl_cv_func_wsastartup], [
-       gl_save_LIBS="$LIBS"
+       gl_saved_LIBS="$LIBS"
        LIBS="$LIBS -lws2_32"
        AC_LINK_IFELSE(
          [AC_LANG_PROGRAM([[
@@ -33,7 +35,7 @@ AC_DEFUN([gl_SOCKETLIB],
          ],
          [gl_cv_func_wsastartup=yes],
          [gl_cv_func_wsastartup=no])
-       LIBS="$gl_save_LIBS"
+       LIBS="$gl_saved_LIBS"
       ])
     if test "$gl_cv_func_wsastartup" = "yes"; then
       AC_DEFINE([WINDOWS_SOCKETS], [1], [Define if WSAStartup is needed.])
@@ -56,8 +58,8 @@ AC_DEFUN([gl_SOCKETLIB],
 #endif
 char setsockopt();]], [[setsockopt();]])],
         [],
-        [gl_save_LIBS="$LIBS"
-         LIBS="$gl_save_LIBS -lsocket"
+        [gl_saved_LIBS="$LIBS"
+         LIBS="$gl_saved_LIBS -lsocket"
          AC_LINK_IFELSE([AC_LANG_PROGRAM([[extern
 #ifdef __cplusplus
 "C"
@@ -65,7 +67,7 @@ char setsockopt();]], [[setsockopt();]])],
 char setsockopt();]], [[setsockopt();]])],
            [gl_cv_lib_socket="-lsocket"])
          if test -z "$gl_cv_lib_socket"; then
-           LIBS="$gl_save_LIBS -lnetwork"
+           LIBS="$gl_saved_LIBS -lnetwork"
            AC_LINK_IFELSE([AC_LANG_PROGRAM([[extern
 #ifdef __cplusplus
 "C"
@@ -73,7 +75,7 @@ char setsockopt();]], [[setsockopt();]])],
 char setsockopt();]], [[setsockopt();]])],
              [gl_cv_lib_socket="-lnetwork"])
            if test -z "$gl_cv_lib_socket"; then
-             LIBS="$gl_save_LIBS -lnet"
+             LIBS="$gl_saved_LIBS -lnet"
              AC_LINK_IFELSE([AC_LANG_PROGRAM([[extern
 #ifdef __cplusplus
 "C"
@@ -82,7 +84,7 @@ char setsockopt();]], [[setsockopt();]])],
                [gl_cv_lib_socket="-lnet"])
            fi
          fi
-         LIBS="$gl_save_LIBS"
+         LIBS="$gl_saved_LIBS"
         ])
       if test -z "$gl_cv_lib_socket"; then
         gl_cv_lib_socket="none needed"
diff --git a/gl/m4/sockets.m4 b/gl/m4/sockets.m4
index ed9cb873..54f4dc79 100644
--- a/gl/m4/sockets.m4
+++ b/gl/m4/sockets.m4
@@ -1,8 +1,10 @@
-# sockets.m4 serial 7
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# sockets.m4
+# serial 7
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_SOCKETS],
 [
diff --git a/gl/m4/socklen.m4 b/gl/m4/socklen.m4
index 1c63a853..a8ac25b1 100644
--- a/gl/m4/socklen.m4
+++ b/gl/m4/socklen.m4
@@ -1,8 +1,10 @@
-# socklen.m4 serial 11
-dnl Copyright (C) 2005-2007, 2009-2023 Free Software Foundation, Inc.
+# socklen.m4
+# serial 11
+dnl Copyright (C) 2005-2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Albert Chin, Windows fixes from Simon Josefsson.
 
diff --git a/gl/m4/sockpfaf.m4 b/gl/m4/sockpfaf.m4
index 6c6dc2f7..08ce843d 100644
--- a/gl/m4/sockpfaf.m4
+++ b/gl/m4/sockpfaf.m4
@@ -1,8 +1,10 @@
-# sockpfaf.m4 serial 10
-dnl Copyright (C) 2004, 2006, 2009-2023 Free Software Foundation, Inc.
+# sockpfaf.m4
+# serial 11
+dnl Copyright (C) 2004, 2006, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Test for some common socket protocol families (PF_INET, PF_INET6, ...)
 dnl and some common address families (AF_INET, AF_INET6, ...).
@@ -63,6 +65,13 @@ AC_DEFUN([gl_SOCKET_FAMILY_UNIX],
   AC_REQUIRE([gl_SYS_SOCKET_H])
   AC_CHECK_HEADERS_ONCE([sys/un.h])
 
+  dnl Windows versions released after 2017 may have support for AF_UNIX.
+  dnl Including it requires types from <winsock2.h> to be defined.
+  dnl <https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/>.
+  if test "$ac_cv_header_winsock2_h" = yes; then
+    AC_CHECK_HEADERS([afunix.h], [], [], [#include <winsock2.h>])
+  fi
+
   AC_CACHE_CHECK([for UNIX domain sockets],
     [gl_cv_socket_unix],
     [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/types.h>
@@ -74,6 +83,9 @@ AC_DEFUN([gl_SOCKET_FAMILY_UNIX],
 #endif
 #ifdef HAVE_WINSOCK2_H
 #include <winsock2.h>
+#endif
+#ifdef HAVE_AFUNIX_H
+#include <afunix.h>
 #endif]],
 [[int x = AF_UNIX; struct sockaddr_un y;
  if (&x && &y) return 0;]])],
diff --git a/gl/m4/ssize_t.m4 b/gl/m4/ssize_t.m4
index 1c12c33e..a2ffd6fc 100644
--- a/gl/m4/ssize_t.m4
+++ b/gl/m4/ssize_t.m4
@@ -1,23 +1,39 @@
-# ssize_t.m4 serial 5 (gettext-0.18.2)
-dnl Copyright (C) 2001-2003, 2006, 2010-2023 Free Software Foundation, Inc.
+# ssize_t.m4
+# serial 6
+dnl Copyright (C) 2001-2003, 2006, 2010-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
-dnl Test whether ssize_t is defined.
+dnl Define ssize_t if it does not already exist.
 
 AC_DEFUN([gt_TYPE_SSIZE_T],
 [
-  AC_CACHE_CHECK([for ssize_t], [gt_cv_ssize_t],
+  AC_CACHE_CHECK([for ssize_t], [gl_cv_ssize_t],
     [AC_COMPILE_IFELSE(
        [AC_LANG_PROGRAM(
           [[#include <sys/types.h>]],
           [[int x = sizeof (ssize_t *) + sizeof (ssize_t);
             return !x;]])],
-       [gt_cv_ssize_t=yes], [gt_cv_ssize_t=no])])
-  if test $gt_cv_ssize_t = no; then
-    AC_DEFINE([ssize_t], [int],
-              [Define as a signed type of the same size as size_t.])
+       [gl_cv_ssize_t=yes], [gl_cv_ssize_t=no])])
+  if test $gl_cv_ssize_t = no; then
+    dnl On 64-bit native Windows, ssize_t needs to be defined as 'long long',
+    dnl for consistency with the 64-bit size_t.
+    AC_CACHE_CHECK([whether size_t is wider than 'long'], [gl_cv_size_t_large],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <sys/types.h>
+              typedef int array [2 * (sizeof (size_t) > sizeof (long)) - 1];
+            ]])],
+         [gl_cv_size_t_large=yes], [gl_cv_size_t_large=no])])
+    if test $gl_cv_size_t_large = yes; then
+      gl_def_ssize_t='long long'
+    else
+      gl_def_ssize_t='long'
+    fi
+    AC_DEFINE_UNQUOTED([ssize_t], [$gl_def_ssize_t],
+                       [Define as a signed type of the same size as size_t.])
   fi
 ])
diff --git a/gl/m4/stat-time.m4 b/gl/m4/stat-time.m4
index 40993d57..4aa24e7f 100644
--- a/gl/m4/stat-time.m4
+++ b/gl/m4/stat-time.m4
@@ -1,11 +1,13 @@
-# Checks for stat-related time functions.
-
-# Copyright (C) 1998-1999, 2001, 2003, 2005-2007, 2009-2023 Free Software
-# Foundation, Inc.
+# stat-time.m4
+# serial 1
+dnl Copyright (C) 1998-1999, 2001, 2003, 2005-2007, 2009-2025 Free Software
+dnl Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# Checks for stat-related time functions.
 
 dnl From Paul Eggert.
 
diff --git a/gl/m4/stat.m4 b/gl/m4/stat.m4
index 4d241e27..66876305 100644
--- a/gl/m4/stat.m4
+++ b/gl/m4/stat.m4
@@ -1,10 +1,10 @@
-# serial 18
-
-# Copyright (C) 2009-2023 Free Software Foundation, Inc.
-#
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# stat.m4
+# serial 21
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_STAT],
 [
@@ -12,7 +12,7 @@ AC_DEFUN([gl_FUNC_STAT],
   AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
   AC_CHECK_FUNCS_ONCE([lstat])
   case "$host_os" in
-    mingw*)
+    mingw* | windows*)
       dnl On this platform, the original stat() returns st_atime, st_mtime,
       dnl st_ctime values that are affected by the time zone.
       REPLACE_STAT=1
@@ -45,6 +45,8 @@ AC_DEFUN([gl_FUNC_STAT],
            [case "$host_os" in
                                # Guess yes on Linux systems.
               linux-* | linux) gl_cv_func_stat_file_slash="guessing yes" ;;
+                               # Guess yes on systems that emulate the Linux system calls.
+              midipix*)        gl_cv_func_stat_file_slash="guessing yes" ;;
                                # Guess yes on glibc systems.
               *-gnu* | gnu*)   gl_cv_func_stat_file_slash="guessing yes" ;;
                                # If we don't know, obey --enable-cross-guesses.
@@ -59,8 +61,8 @@ AC_DEFUN([gl_FUNC_STAT],
             help when passed a file name with a trailing slash]);;
       esac
       case $host_os in
-        dnl Solaris stat can return a negative tv_nsec.
-        solaris*)
+        dnl macOS and Solaris stat can return a negative tv_nsec.
+        darwin* | solaris*)
           REPLACE_FSTAT=1 ;;
       esac
       ;;
@@ -78,7 +80,7 @@ AC_DEFUN([gl_PREREQ_STAT], [
 AC_DEFUN([gl_PREREQ_STAT_W32], [
   AC_REQUIRE([AC_CANONICAL_HOST])
   case "$host_os" in
-    mingw*)
+    mingw* | windows*)
       AC_CHECK_HEADERS([sdkddkver.h])
       ;;
   esac
diff --git a/gl/m4/std-gnu11.m4 b/gl/m4/std-gnu11.m4
index 4179470e..762764e0 100644
--- a/gl/m4/std-gnu11.m4
+++ b/gl/m4/std-gnu11.m4
@@ -1,19 +1,27 @@
+# std-gnu11.m4
+# serial 3
+
 # Prefer GNU C11 and C++11 to earlier versions.  -*- coding: utf-8 -*-
 
+# The std-gnu23 module, which defines _AC_C_C23_OPTIONS, supersedes us.
+m4_ifndef([_AC_C_C23_OPTIONS], [
+
 # This implementation is taken from GNU Autoconf lib/autoconf/c.m4
 # commit 017d5ddd82854911f0119691d91ea8a1438824d6
 # dated Sun Apr 3 13:57:17 2016 -0700
+# with minor changes to commentary.
 # This implementation will be obsolete once we can assume Autoconf 2.70
 # or later is installed everywhere a Gnulib program might be developed.
 
 m4_version_prereq([2.70], [], [
 
 
-# Copyright (C) 2001-2023 Free Software Foundation, Inc.
+# Copyright (C) 2001-2025 Free Software Foundation, Inc.
 
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
+# This file is part of Autoconf.  This program is free
+# software; you can redistribute it and/or modify it under the
+# terms of the GNU General Public License as published by the
+# Free Software Foundation, either version 3 of the License, or
 # (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
@@ -21,8 +29,15 @@ m4_version_prereq([2.70], [], [
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
+# Under Section 7 of GPL version 3, you are granted additional
+# permissions described in the Autoconf Configure Script Exception,
+# version 3.0, as published by the Free Software Foundation.
+#
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+# and a copy of the Autoconf Configure Script Exception along with
+# this program; see the files COPYINGv3 and COPYING.EXCEPTION
+# respectively.  If not, see <https://www.gnu.org/licenses/> and
+# <https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=blob_plain;f=COPYING.EXCEPTION>.
 
 # Written by David MacKenzie, with help from
 # Akim Demaille, Paul Eggert,
@@ -35,7 +50,7 @@ m4_version_prereq([2.70], [], [
 # COMPILER ... is a space separated list of C compilers to search for.
 # This just gives the user an opportunity to specify an alternative
 # search list for the C compiler.
-AC_DEFUN_ONCE([AC_PROG_CC],
+AC_DEFUN([AC_PROG_CC],
 [AC_LANG_PUSH(C)dnl
 AC_ARG_VAR([CC],     [C compiler command])dnl
 AC_ARG_VAR([CFLAGS], [C compiler flags])dnl
@@ -827,3 +842,4 @@ dnl with extended modes being tried first.
 
 
 ])# m4_version_prereq
+])# !_AC_C_C23_OPTIONS
diff --git a/gl/m4/stdalign.m4 b/gl/m4/stdalign.m4
index dc297175..885feafd 100644
--- a/gl/m4/stdalign.m4
+++ b/gl/m4/stdalign.m4
@@ -1,20 +1,25 @@
-# Check for alignas and alignof that conform to C23.
-
-dnl Copyright 2011-2023 Free Software Foundation, Inc.
+# stdalign.m4
+# serial 3
+dnl Copyright 2011-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+# Check for alignas and alignof that conform to C23.
+
+dnl Written by Paul Eggert and Bruno Haible.
 
 # Prepare for substituting <stdalign.h> if it is not supported.
 
-AC_DEFUN([gl_STDALIGN_H],
+AC_DEFUN([gl_ALIGNASOF],
 [
   AC_CACHE_CHECK([for alignas and alignof],
     [gl_cv_header_working_stdalign_h],
-    [gl_save_CFLAGS=$CFLAGS
+    [gl_saved_CFLAGS=$CFLAGS
      for gl_working in "yes, keywords" "yes, <stdalign.h> macros"; do
       AS_CASE([$gl_working],
-        [*stdalign.h*], [CFLAGS="$gl_save_CFLAGS -DINCLUDE_STDALIGN_H"])
+        [*stdalign.h*], [CFLAGS="$gl_saved_CFLAGS -DINCLUDE_STDALIGN_H"])
       AC_COMPILE_IFELSE(
        [AC_LANG_PROGRAM(
           [[#include <stdint.h>
@@ -54,85 +59,154 @@ AC_DEFUN([gl_STDALIGN_H],
        [gl_cv_header_working_stdalign_h=$gl_working],
        [gl_cv_header_working_stdalign_h=no])
 
-      CFLAGS=$gl_save_CFLAGS
+      CFLAGS=$gl_saved_CFLAGS
       test "$gl_cv_header_working_stdalign_h" != no && break
      done])
 
-  GL_GENERATE_STDALIGN_H=false
   AS_CASE([$gl_cv_header_working_stdalign_h],
-    [no],
-      [GL_GENERATE_STDALIGN_H=true],
     [yes*keyword*],
       [AC_DEFINE([HAVE_C_ALIGNASOF], [1],
          [Define to 1 if the alignas and alignof keywords work.])])
 
-  AC_CHECK_HEADERS_ONCE([stdalign.h])
-
   dnl The "zz" puts this toward config.h's end, to avoid potential
   dnl collisions with other definitions.
   AH_VERBATIM([zzalignas],
-[#if !defined HAVE_C_ALIGNASOF && __cplusplus < 201103 && !defined alignof
-# if HAVE_STDALIGN_H
+[#if !defined HAVE_C_ALIGNASOF \
+    && !(defined __cplusplus && 201103 <= __cplusplus) \
+    && !defined alignof
+# if defined HAVE_STDALIGN_H
 #  include <stdalign.h>
-# else
-   /* Substitute.  Keep consistent with gnulib/lib/stdalign.in.h.  */
-#  ifndef _GL_STDALIGN_H
-#   define _GL_STDALIGN_H
-#   undef _Alignas
-#   undef _Alignof
-#   if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \
-        || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \
-            && !defined __clang__) \
-        || (defined __clang__ && __clang_major__ < 8))
-#    ifdef __cplusplus
-#     if (201103 <= __cplusplus || defined _MSC_VER)
-#      define _Alignof(type) alignof (type)
-#     else
-       template <class __t> struct __alignof_helper { char __a; __t __b; };
-#      define _Alignof(type) offsetof (__alignof_helper<type>, __b)
-#      define _GL_STDALIGN_NEEDS_STDDEF 1
-#     endif
+# endif
+
+/* ISO C23 alignas and alignof for platforms that lack it.
+
+   References:
+   ISO C23 (latest free draft
+   <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3096.pdf>)
+   sections 6.5.3.4, 6.7.5, 7.15.
+   C++11 (latest free draft
+   <https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf>)
+   section 18.10. */
+
+/* alignof (TYPE), also known as _Alignof (TYPE), yields the alignment
+   requirement of a structure member (i.e., slot or field) that is of
+   type TYPE, as an integer constant expression.
+
+   This differs from GCC's and clang's __alignof__ operator, which can
+   yield a better-performing alignment for an object of that type.  For
+   example, on x86 with GCC and on Linux/x86 with clang,
+   __alignof__ (double) and __alignof__ (long long) are 8, whereas
+   alignof (double) and alignof (long long) are 4 unless the option
+   '-malign-double' is used.
+
+   The result cannot be used as a value for an 'enum' constant, if you
+   want to be portable to HP-UX 10.20 cc and AIX 3.2.5 xlc.  */
+
+/* GCC releases before GCC 4.9 had a bug in _Alignof.  See GCC bug 52023
+   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>.
+   clang versions < 8.0.0 have the same bug.
+   IBM XL C V16.1.0 cc (non-clang) has the same bug.  */
+#  if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \
+       || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \
+           && !defined __clang__) \
+       || (defined __clang__ && __clang_major__ < 8) \
+       || defined __xlC__)
+#   undef/**/_Alignof
+#   ifdef __cplusplus
+#    if (201103 <= __cplusplus || defined _MSC_VER)
+#     define _Alignof(type) alignof (type)
 #    else
+      template <class __t> struct __alignof_helper { char __a; __t __b; };
 #     if (defined __GNUC__ && 4 <= __GNUC__) || defined __clang__
-#      define _Alignof(type) __builtin_offsetof (struct { char __a; type __b; }, __b)
+#      define _Alignof(type) __builtin_offsetof (__alignof_helper<type>, __b)
 #     else
-#      define _Alignof(type) offsetof (struct { char __a; type __b; }, __b)
-#      define _GL_STDALIGN_NEEDS_STDDEF 1
+#      define _Alignof(type) offsetof (__alignof_helper<type>, __b)
 #     endif
+#     define _GL_STDALIGN_NEEDS_STDDEF 1
 #    endif
-#   endif
-#   if ! (defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER))
-#    define alignof _Alignof
-#   endif
-#   define __alignof_is_defined 1
-#   if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112
-#    if defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER)
-#     define _Alignas(a) alignas (a)
-#    elif (!defined __attribute__ \
-           && ((defined __APPLE__ && defined __MACH__ \
-                ? 4 < __GNUC__ + (1 <= __GNUC_MINOR__) \
-                : __GNUC__ && !defined __ibmxl__) \
-               || (4 <= __clang_major__) \
-               || (__ia64 && (61200 <= __HP_cc || 61200 <= __HP_aCC)) \
-               || __ICC || 0x590 <= __SUNPRO_C || 0x0600 <= __xlC__))
-#     define _Alignas(a) __attribute__ ((__aligned__ (a)))
-#    elif 1300 <= _MSC_VER
-#     define _Alignas(a) __declspec (align (a))
+#   else
+#    if (defined __GNUC__ && 4 <= __GNUC__) || defined __clang__
+#     define _Alignof(type) __builtin_offsetof (struct { char __a; type __b; }, __b)
+#    else
+#     define _Alignof(type) offsetof (struct { char __a; type __b; }, __b)
+#     define _GL_STDALIGN_NEEDS_STDDEF 1
 #    endif
 #   endif
-#   if ((defined _Alignas \
-         && !(defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER))) \
-        || (defined __STDC_VERSION__ && 201112 <= __STDC_VERSION__))
-#    define alignas _Alignas
-#   endif
-#   if (defined alignas \
-        || (defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER)))
-#    define __alignas_is_defined 1
-#   endif
-#   if _GL_STDALIGN_NEEDS_STDDEF
-#    include <stddef.h>
-#   endif
-#  endif /* _GL_STDALIGN_H */
+#  endif
+#  if ! (defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER))
+#   undef/**/alignof
+#   define alignof _Alignof
+#  endif
+
+/* alignas (A), also known as _Alignas (A), aligns a variable or type
+   to the alignment A, where A is an integer constant expression.  For
+   example:
+
+      int alignas (8) foo;
+      struct s { int a; int alignas (8) bar; };
+
+   aligns the address of FOO and the offset of BAR to be multiples of 8.
+
+   A should be a power of two that is at least the type's alignment
+   and at most the implementation's alignment limit.  This limit is
+   2**28 on typical GNUish hosts, and 2**13 on MSVC.  To be portable
+   to MSVC through at least version 10.0, A should be an integer
+   constant, as MSVC does not support expressions such as 1 << 3.
+   To be portable to Sun C 5.11, do not align auto variables to
+   anything stricter than their default alignment.
+
+   The following C23 requirements are not supported here:
+
+     - If A is zero, alignas has no effect.
+     - alignas can be used multiple times; the strictest one wins.
+     - alignas (TYPE) is equivalent to alignas (alignof (TYPE)).
+
+   */
+# if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112
+#  if defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER)
+#   define _Alignas(a) alignas (a)
+#  elif (!defined __attribute__ \
+         && ((defined __APPLE__ && defined __MACH__ \
+              ? 4 < __GNUC__ + (1 <= __GNUC_MINOR__) \
+              : __GNUC__ && !defined __ibmxl__) \
+             || (4 <= __clang_major__) \
+             || (__ia64 && (61200 <= __HP_cc || 61200 <= __HP_aCC)) \
+             || __ICC || 0x590 <= __SUNPRO_C || 0x0600 <= __xlC__))
+#   define _Alignas(a) __attribute__ ((__aligned__ (a)))
+#  elif 1300 <= _MSC_VER
+#   define _Alignas(a) __declspec (align (a))
+#  endif
+# endif
+# if !defined HAVE_STDALIGN_H
+#  if ((defined _Alignas \
+        && !(defined __cplusplus \
+             && (201103 <= __cplusplus || defined _MSC_VER))) \
+       || (defined __STDC_VERSION__ && 201112 <= __STDC_VERSION__ \
+           && !defined __xlC__))
+#   define alignas _Alignas
+#  endif
+# endif
+
+# if defined _GL_STDALIGN_NEEDS_STDDEF
+#  include <stddef.h>
 # endif
 #endif])
 ])
+
+AC_DEFUN([gl_STDALIGN_H],
+[
+  AC_REQUIRE([gl_ALIGNASOF])
+  if test "$gl_cv_header_working_stdalign_h" = no; then
+    GL_GENERATE_STDALIGN_H=true
+  else
+    GL_GENERATE_STDALIGN_H=false
+  fi
+
+  gl_CHECK_NEXT_HEADERS([stdalign.h])
+  if test $ac_cv_header_stdalign_h = yes; then
+    HAVE_STDALIGN_H=1
+  else
+    HAVE_STDALIGN_H=0
+  fi
+  AC_SUBST([HAVE_STDALIGN_H])
+])
diff --git a/gl/m4/stdckdint_h.m4 b/gl/m4/stdckdint_h.m4
new file mode 100644
index 00000000..d269faa5
--- /dev/null
+++ b/gl/m4/stdckdint_h.m4
@@ -0,0 +1,136 @@
+# stdckdint_h.m4
+# serial 1
+dnl Copyright 2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl Written by Collin Funk.
+
+AC_DEFUN_ONCE([gl_STDCKDINT_H],
+[
+  gl_CHECK_NEXT_HEADERS([stdckdint.h])
+  if test $ac_cv_header_stdckdint_h = yes; then
+    HAVE_STDCKDINT_H=1
+  else
+    HAVE_STDCKDINT_H=0
+  fi
+  AC_SUBST([HAVE_STDCKDINT_H])
+
+  if test $HAVE_STDCKDINT_H = 1; then
+    AC_CACHE_CHECK([whether stdckdint.h can be included in C],
+      [gl_cv_header_c_stdckdint_h],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <stdckdint.h>
+            ]])],
+         [gl_cv_header_c_stdckdint_h=yes],
+         [gl_cv_header_c_stdckdint_h=no])])
+    if test $gl_cv_header_c_stdckdint_h = yes; then
+      HAVE_C_STDCKDINT_H=1
+      AC_CACHE_CHECK([checking for an ISO C23 compliant stdckdint.h in C],
+        [gl_cv_header_c_stdckdint_h_works],
+        [AC_COMPILE_IFELSE(
+           [AC_LANG_PROGRAM(
+              [[#include <stdckdint.h>
+              ]],
+              [[int r;
+                int a = 1;
+                int b = 1;
+                return !!(ckd_add (&r, a, b) || ckd_sub (&r, a, b)
+                          || ckd_mul (&r, a, b));
+              ]])],
+           [gl_cv_header_c_stdckdint_h_works=yes],
+           [gl_cv_header_c_stdckdint_h_works=no])])
+      if test $gl_cv_header_c_stdckdint_h_works = yes; then
+        HAVE_WORKING_C_STDCKDINT_H=1
+      else
+        HAVE_WORKING_C_STDCKDINT_H=0
+      fi
+    else
+      HAVE_C_STDCKDINT_H=0
+      HAVE_WORKING_C_STDCKDINT_H=0
+    fi
+    if test "$CXX" != no; then
+      AC_CACHE_CHECK([whether stdckdint.h can be included in C++],
+        [gl_cv_header_cxx_stdckdint_h],
+        [dnl We can't use AC_LANG_PUSH([C++]) and AC_LANG_POP([C++]) here, due to
+         dnl an autoconf bug <https://savannah.gnu.org/support/?110294>.
+         cat > conftest.cpp <<\EOF
+#include <stdckdint.h>
+EOF
+         gl_command="$CXX $CXXFLAGS $CPPFLAGS -c conftest.cpp"
+         if AC_TRY_EVAL([gl_command]); then
+           gl_cv_header_cxx_stdckdint_h=yes
+         else
+           gl_cv_header_cxx_stdckdint_h=no
+         fi
+         rm -fr conftest*
+        ])
+      if test $gl_cv_header_cxx_stdckdint_h = yes; then
+        HAVE_CXX_STDCKDINT_H=1
+        AC_CACHE_CHECK([checking for an ISO C++26 compliant stdckdint.h in C++],
+          [gl_cv_header_cxx_stdckdint_h_works],
+          [dnl We can't use AC_LANG_PUSH([C++]) and AC_LANG_POP([C++]) here, due to
+           dnl an autoconf bug <https://savannah.gnu.org/support/?110294>.
+           cat > conftest.cpp <<\EOF
+#include <stdckdint.h>
+int
+main (void)
+{
+  int r;
+  int a = 1;
+  int b = 1;
+  return !!(ckd_add (&r, a, b) || ckd_sub (&r, a, b) || ckd_mul (&r, a, b));
+}
+EOF
+           gl_command="$CXX $CXXFLAGS $CPPFLAGS -c conftest.cpp"
+           if AC_TRY_EVAL([gl_command]); then
+             gl_cv_header_cxx_stdckdint_h_works=yes
+           else
+             gl_cv_header_cxx_stdckdint_h_works=no
+           fi
+           rm -fr conftest*
+          ])
+        if test $gl_cv_header_cxx_stdckdint_h_works = yes; then
+          HAVE_WORKING_CXX_STDCKDINT_H=1
+        else
+          HAVE_WORKING_CXX_STDCKDINT_H=0
+        fi
+      else
+        HAVE_CXX_STDCKDINT_H=0
+        HAVE_WORKING_CXX_STDCKDINT_H=0
+      fi
+    fi
+  else
+    HAVE_C_STDCKDINT_H=0
+    HAVE_WORKING_C_STDCKDINT_H=0
+    HAVE_CXX_STDCKDINT_H=0
+    HAVE_WORKING_CXX_STDCKDINT_H=0
+  fi
+  AC_SUBST([HAVE_C_STDCKDINT_H])
+  AC_SUBST([HAVE_WORKING_C_STDCKDINT_H])
+  AC_SUBST([HAVE_CXX_STDCKDINT_H])
+  AC_SUBST([HAVE_WORKING_CXX_STDCKDINT_H])
+
+  if test "$CXX" != no; then
+    dnl We might need the header for C or C++.
+    if test $HAVE_C_STDCKDINT_H = 1 \
+       && test $HAVE_WORKING_C_STDCKDINT_H = 1 \
+       && test $HAVE_CXX_STDCKDINT_H = 1 \
+       && test $HAVE_WORKING_CXX_STDCKDINT_H = 1; then
+      GL_GENERATE_STDCKDINT_H=false
+    else
+      GL_GENERATE_STDCKDINT_H=true
+    fi
+  else
+    dnl We don't care about C++ here.
+    if test $HAVE_C_STDCKDINT_H = 1 \
+       && test $HAVE_WORKING_C_STDCKDINT_H = 1; then
+      GL_GENERATE_STDCKDINT_H=false
+    else
+      GL_GENERATE_STDCKDINT_H=true
+    fi
+  fi
+])
diff --git a/gl/m4/stddef_h.m4 b/gl/m4/stddef_h.m4
index a2322ebb..127ec05b 100644
--- a/gl/m4/stddef_h.m4
+++ b/gl/m4/stddef_h.m4
@@ -1,15 +1,16 @@
-# stddef_h.m4 serial 13
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# stddef_h.m4
+# serial 23
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl A placeholder for <stddef.h>, for platforms that have issues.
 
 AC_DEFUN_ONCE([gl_STDDEF_H],
 [
   AC_REQUIRE([gl_STDDEF_H_DEFAULTS])
-  AC_REQUIRE([gt_TYPE_WCHAR_T])
 
   dnl Persuade OpenBSD <stddef.h> to declare max_align_t.
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
@@ -51,11 +52,6 @@ AC_DEFUN_ONCE([gl_STDDEF_H],
     GL_GENERATE_STDDEF_H=true
   fi
 
-  if test $gt_cv_c_wchar_t = no; then
-    HAVE_WCHAR_T=0
-    GL_GENERATE_STDDEF_H=true
-  fi
-
   AC_CACHE_CHECK([whether NULL can be used in arbitrary expressions],
     [gl_cv_decl_null_works],
     [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stddef.h>
@@ -68,6 +64,60 @@ AC_DEFUN_ONCE([gl_STDDEF_H],
     GL_GENERATE_STDDEF_H=true
   fi
 
+  AC_CACHE_CHECK([for unreachable in C],
+    [gl_cv_c_func_unreachable],
+    [AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stddef.h>
+          ]],
+          [[unreachable ();
+          ]])],
+       [gl_cv_c_func_unreachable=yes],
+       [gl_cv_c_func_unreachable=no])
+    ])
+  if test $gl_cv_c_func_unreachable = no; then
+    GL_GENERATE_STDDEF_H=true
+    HAVE_C_UNREACHABLE=0
+  else
+    HAVE_C_UNREACHABLE=1
+  fi
+  AC_SUBST([HAVE_C_UNREACHABLE])
+  dnl Provide gl_unreachable() unconditionally.
+  GL_GENERATE_STDDEF_H=true
+
+  dnl https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114869
+  AC_CACHE_CHECK([whether nullptr_t needs <stddef.h>],
+    [gl_cv_nullptr_t_needs_stddef],
+    [AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[nullptr_t x;]],
+       [gl_cv_nullptr_t_needs_stddef=no],
+       [gl_cv_nullptr_t_needs_stddef=yes])])
+  if test "$gl_cv_nullptr_t_needs_stddef" = no; then
+    NULLPTR_T_NEEDS_STDDEF=0
+    GL_GENERATE_STDDEF_H=true
+  fi
+
+  dnl https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114870
+  dnl affects GCC 13.3 and 14.2.
+  AC_CACHE_CHECK([whether <stddef.h> is idempotent],
+    [gl_cv_stddef_idempotent],
+    [AC_COMPILE_IFELSE([AC_LANG_SOURCE(
+       [[
+       #if \
+           ((__GNUC__ == 13 && __GNUC_MINOR__ <= 3) \
+            || (__GNUC__ == 14 && __GNUC_MINOR__ <= 2))
+        #error "bug 114870 is present"
+       #endif
+       ]])],
+       [gl_cv_stddef_idempotent="guessing yes"],
+       [gl_cv_stddef_idempotent="guessing no"])
+    ])
+  case "$gl_cv_stddef_idempotent" in
+    *yes) ;;
+    *) STDDEF_NOT_IDEMPOTENT=1
+       GL_GENERATE_STDDEF_H=true
+       ;;
+  esac
+
   if $GL_GENERATE_STDDEF_H; then
     gl_NEXT_HEADERS([stddef.h])
   fi
@@ -98,7 +148,8 @@ AC_DEFUN([gl_STDDEF_H_REQUIRE_DEFAULTS],
 AC_DEFUN([gl_STDDEF_H_DEFAULTS],
 [
   dnl Assume proper GNU behavior unless another module says otherwise.
+  NULLPTR_T_NEEDS_STDDEF=1;      AC_SUBST([NULLPTR_T_NEEDS_STDDEF])
+  STDDEF_NOT_IDEMPOTENT=0;       AC_SUBST([STDDEF_NOT_IDEMPOTENT])
   REPLACE_NULL=0;                AC_SUBST([REPLACE_NULL])
   HAVE_MAX_ALIGN_T=1;            AC_SUBST([HAVE_MAX_ALIGN_T])
-  HAVE_WCHAR_T=1;                AC_SUBST([HAVE_WCHAR_T])
 ])
diff --git a/gl/m4/stdint.m4 b/gl/m4/stdint.m4
index d6961b09..2d69088b 100644
--- a/gl/m4/stdint.m4
+++ b/gl/m4/stdint.m4
@@ -1,8 +1,10 @@
-# stdint.m4 serial 61
-dnl Copyright (C) 2001-2023 Free Software Foundation, Inc.
+# stdint.m4
+# serial 64
+dnl Copyright (C) 2001-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Paul Eggert and Bruno Haible.
 dnl Test whether <stdint.h> is supported or must be substituted.
@@ -150,10 +152,13 @@ intmax_t i = INTMAX_MAX;
 uintmax_t j = UINTMAX_MAX;
 
 /* Check that SIZE_MAX has the correct type, if possible.  */
-#if 201112 <= __STDC_VERSION__
+/* ISO C 11 mandates _Generic, but GCC versions < 4.9 lack it.  */
+#if 201112 <= __STDC_VERSION__ \
+    && (!defined __GNUC__ || 4 < __GNUC__ + (9 <= __GNUC_MINOR__) \
+        || defined __clang__)
 int k = _Generic (SIZE_MAX, size_t: 0);
 #elif (2 <= __GNUC__ || 4 <= __clang_major__ || defined __IBM__TYPEOF__ \
-       || (0x5110 <= __SUNPRO_C && !__STDC__))
+       || (0x5110 <= __SUNPRO_C && !__STDC__) || 1939 <= _MSC_VER)
 extern size_t k;
 extern __typeof__ (SIZE_MAX) k;
 #endif
@@ -283,10 +288,10 @@ static const char *macro_values[] =
               [gl_cv_header_working_stdint_h=yes],
               [],
               [case "$host_os" in
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_header_working_stdint_h="guessing yes" ;;
-                         # In general, assume it works.
-                 *)      gl_cv_header_working_stdint_h="guessing yes" ;;
+                                    # Guess yes on native Windows.
+                 mingw* | windows*) gl_cv_header_working_stdint_h="guessing yes" ;;
+                                    # In general, assume it works.
+                 *)                 gl_cv_header_working_stdint_h="guessing yes" ;;
                esac
               ])
          ])
diff --git a/gl/m4/stdint_h.m4 b/gl/m4/stdint_h.m4
index 70349f6c..d4f1acdd 100644
--- a/gl/m4/stdint_h.m4
+++ b/gl/m4/stdint_h.m4
@@ -1,8 +1,10 @@
-# stdint_h.m4 serial 9
-dnl Copyright (C) 1997-2004, 2006, 2008-2023 Free Software Foundation, Inc.
+# stdint_h.m4
+# serial 9
+dnl Copyright (C) 1997-2004, 2006, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Paul Eggert.
 
diff --git a/gl/m4/stdio_h.m4 b/gl/m4/stdio_h.m4
index 94271e11..71d86180 100644
--- a/gl/m4/stdio_h.m4
+++ b/gl/m4/stdio_h.m4
@@ -1,12 +1,24 @@
-# stdio_h.m4 serial 59
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# stdio_h.m4
+# serial 75
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-AC_DEFUN_ONCE([gl_STDIO_H],
+AC_DEFUN([gl_STDIO_H_EARLY],
 [
-  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  dnl Defining __USE_MINGW_ANSI_STDIO to 1 must be done early, because
+  dnl the results of several configure tests depend on it: The tests
+  dnl   - checking whether snprintf returns a byte count as in C99...
+  dnl   - checking whether snprintf truncates the result as in C99...
+  dnl   - checking whether printf supports the 'F' directive...
+  dnl   - checking whether printf supports the grouping flag...
+  dnl   - checking whether printf supports the zero flag correctly...
+  dnl   - checking whether printf supports infinite 'double' arguments...
+  dnl   - checking whether printf supports large precisions...
+  dnl report 'yes' if __USE_MINGW_ANSI_STDIO is 1 but 'no' if
+  dnl __USE_MINGW_ANSI_STDIO is not set.
   AH_VERBATIM([MINGW_ANSI_STDIO],
 [/* Use GNU style printf and scanf.  */
 #ifndef __USE_MINGW_ANSI_STDIO
@@ -14,6 +26,11 @@ AC_DEFUN_ONCE([gl_STDIO_H],
 #endif
 ])
   AC_DEFINE([__USE_MINGW_ANSI_STDIO])
+])
+
+AC_DEFUN_ONCE([gl_STDIO_H],
+[
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
   gl_NEXT_HEADERS([stdio.h])
 
   dnl Determine whether __USE_MINGW_ANSI_STDIO makes printf and
@@ -40,6 +57,9 @@ AC_DEFUN_ONCE([gl_STDIO_H],
        attribute "__gnu_printf__" instead of "__printf__"])
   fi
 
+  dnl For defining _PRINTF_NAN_LEN_MAX.
+  gl_MUSL_LIBC
+
   dnl This ifdef is an optimization, to avoid performing a configure check whose
   dnl result is not used. But it does not make the test of
   dnl GNULIB_STDIO_H_NONBLOCKING or GNULIB_NONBLOCKING redundant.
@@ -82,6 +102,16 @@ AC_DEFUN_ONCE([gl_STDIO_H],
   if test $ac_cv_have_decl_fcloseall = no; then
     HAVE_DECL_FCLOSEALL=0
   fi
+
+  AC_CHECK_DECLS_ONCE([getw])
+  if test $ac_cv_have_decl_getw = no; then
+    HAVE_DECL_GETW=0
+  fi
+
+  AC_CHECK_DECLS_ONCE([putw])
+  if test $ac_cv_have_decl_putw = no; then
+    HAVE_DECL_PUTW=0
+  fi
 ])
 
 # gl_STDIO_MODULE_INDICATOR([modulename])
@@ -104,6 +134,7 @@ AC_DEFUN([gl_STDIO_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDIO_H_MODULE_INDICATOR_DEFAULTS], [
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_DZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FCLOSE])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FDOPEN])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FFLUSH])
@@ -124,12 +155,14 @@ AC_DEFUN([gl_STDIO_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FTELL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FTELLO])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FWRITE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETC])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETCHAR])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETDELIM])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETLINE])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OBSTACK_PRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OBSTACK_PRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_OBSTACK_ZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PCLOSE])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PERROR])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_POPEN])
@@ -143,20 +176,29 @@ AC_DEFUN([gl_STDIO_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RENAMEAT])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SCANF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SNPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SNZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SPRINTF_POSIX])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STDIO_H_NONBLOCKING])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STDIO_H_SIGPIPE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TMPFILE])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VASPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VASZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VFSCANF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VSCANF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VDPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VDZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VFPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VFPRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VFZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VPRINTF_POSIX])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VSNPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VSNZPRINTF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VSPRINTF_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VSZPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_VZPRINTF])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ZPRINTF])
     dnl Support Microsoft deprecated alias function names by default.
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_FCLOSEALL], [1])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_FDOPEN], [1])
@@ -178,7 +220,9 @@ AC_DEFUN([gl_STDIO_H_DEFAULTS],
   HAVE_DECL_FTELLO=1;            AC_SUBST([HAVE_DECL_FTELLO])
   HAVE_DECL_GETDELIM=1;          AC_SUBST([HAVE_DECL_GETDELIM])
   HAVE_DECL_GETLINE=1;           AC_SUBST([HAVE_DECL_GETLINE])
+  HAVE_DECL_GETW=1;              AC_SUBST([HAVE_DECL_GETW])
   HAVE_DECL_OBSTACK_PRINTF=1;    AC_SUBST([HAVE_DECL_OBSTACK_PRINTF])
+  HAVE_DECL_PUTW=1;              AC_SUBST([HAVE_DECL_PUTW])
   HAVE_DECL_SNPRINTF=1;          AC_SUBST([HAVE_DECL_SNPRINTF])
   HAVE_DECL_VSNPRINTF=1;         AC_SUBST([HAVE_DECL_VSNPRINTF])
   HAVE_DPRINTF=1;                AC_SUBST([HAVE_DPRINTF])
diff --git a/gl/m4/stdlib_h.m4 b/gl/m4/stdlib_h.m4
index e96be22f..2d25da37 100644
--- a/gl/m4/stdlib_h.m4
+++ b/gl/m4/stdlib_h.m4
@@ -1,8 +1,10 @@
-# stdlib_h.m4 serial 66
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# stdlib_h.m4
+# serial 84
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_STDLIB_H],
 [
@@ -23,15 +25,65 @@ AC_DEFUN_ONCE([gl_STDLIB_H],
 # include <random.h>
 #endif
     ]], [_Exit aligned_alloc atoll canonicalize_file_name free
-    getloadavg getsubopt grantpt
-    initstate initstate_r mbtowc mkdtemp mkostemp mkostemps mkstemp mkstemps
-    posix_memalign posix_openpt ptsname ptsname_r qsort_r
+    getloadavg getprogname getsubopt grantpt
+    initstate initstate_r mbstowcs mbtowc mkdtemp mkostemp mkostemps mkstemp
+    mkstemps posix_memalign posix_openpt ptsname ptsname_r qsort_r
     random random_r reallocarray realpath rpmatch secure_getenv setenv
     setstate setstate_r srandom srandom_r
     strtod strtol strtold strtoll strtoul strtoull unlockpt unsetenv])
 
   AC_REQUIRE([AC_C_RESTRICT])
 
+  dnl Test whether MB_CUR_MAX needs to be overridden.
+  dnl On Solaris 10, in UTF-8 locales, its value is 3 but needs to be 4.
+  dnl Fortunately, we can do this because on this platform MB_LEN_MAX is 5.
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gt_LOCALE_EN_UTF8])
+  AC_CACHE_CHECK([whether MB_CUR_MAX is correct],
+    [gl_cv_macro_MB_CUR_MAX_good],
+    [AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM([[#include <stdlib.h>
+                        ]],
+                        [[return !!MB_CUR_MAX;]])
+       ],
+       [dnl Initial guess, used when cross-compiling or when no suitable locale
+        dnl is present.
+        # Guess no on Solaris and Haiku, yes otherwise.
+        AS_CASE([$host_os],
+          [solaris* | haiku*],
+            [gl_cv_macro_MB_CUR_MAX_good="guessing no"],
+            [gl_cv_macro_MB_CUR_MAX_good="guessing yes"])
+        if test "$LOCALE_EN_UTF8" != none; then
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdlib.h>
+int main ()
+{
+  int result = 0;
+  if (setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
+    {
+      if (MB_CUR_MAX < 4)
+        result |= 1;
+    }
+  return result;
+}]])],
+            [gl_cv_macro_MB_CUR_MAX_good=yes],
+            [gl_cv_macro_MB_CUR_MAX_good=no],
+            [:])
+        fi
+       ],
+       [gl_cv_macro_MB_CUR_MAX_good="link failed - so no"])
+    ])
+  AS_CASE([$gl_cv_macro_MB_CUR_MAX_good],
+    [*yes],
+      [],
+    ["link failed - so no"],
+      [# 4 suffices as a workaround in Android NDK 16,
+       # the only known platform with the bug.
+       REPLACE_MB_CUR_MAX=4],
+      [REPLACE_MB_CUR_MAX="(-1)"])
+
   AC_CHECK_DECLS_ONCE([ecvt])
   if test $ac_cv_have_decl_ecvt = no; then
     HAVE_DECL_ECVT=0
@@ -66,6 +118,7 @@ AC_DEFUN([gl_STDLIB_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDLIB_H_MODULE_INDICATOR_DEFAULTS], [
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB__EXIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ABORT_DEBUG])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ALIGNED_ALLOC])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ATOLL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CALLOC_GNU])
@@ -73,10 +126,12 @@ AC_DEFUN([gl_STDLIB_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_CANONICALIZE_FILE_NAME])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FREE_POSIX])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETLOADAVG])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETPROGNAME])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GETSUBOPT])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_GRANTPT])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MALLOC_GNU])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MALLOC_POSIX])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSTOWCS])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBTOWC])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKDTEMP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MKOSTEMP])
@@ -89,16 +144,18 @@ AC_DEFUN([gl_STDLIB_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PTSNAME_R])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PUTENV])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_QSORT_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RAND])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RANDOM])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RANDOM_R])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REALLOCARRAY])
-    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REALLOC_GNU])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REALLOC_POSIX])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_REALPATH])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_RPMATCH])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SECURE_GETENV])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SETENV])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STACK_TRACE])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOD])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOF])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOLD])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOLL])
@@ -130,6 +187,8 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   HAVE_DECL_FCVT=1;          AC_SUBST([HAVE_DECL_FCVT])
   HAVE_DECL_GCVT=1;          AC_SUBST([HAVE_DECL_GCVT])
   HAVE_DECL_GETLOADAVG=1;    AC_SUBST([HAVE_DECL_GETLOADAVG])
+  HAVE_DECL_PROGRAM_INVOCATION_NAME=1; AC_SUBST([HAVE_DECL_PROGRAM_INVOCATION_NAME])
+  HAVE_GETPROGNAME=1;        AC_SUBST([HAVE_GETPROGNAME])
   HAVE_GETSUBOPT=1;          AC_SUBST([HAVE_GETSUBOPT])
   HAVE_GRANTPT=1;            AC_SUBST([HAVE_GRANTPT])
   HAVE_INITSTATE=1;          AC_SUBST([HAVE_INITSTATE])
@@ -157,6 +216,7 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   HAVE_SETSTATE=1;           AC_SUBST([HAVE_SETSTATE])
   HAVE_DECL_SETSTATE=1;      AC_SUBST([HAVE_DECL_SETSTATE])
   HAVE_STRTOD=1;             AC_SUBST([HAVE_STRTOD])
+  HAVE_STRTOF=1;             AC_SUBST([HAVE_STRTOF])
   HAVE_STRTOL=1;             AC_SUBST([HAVE_STRTOL])
   HAVE_STRTOLD=1;            AC_SUBST([HAVE_STRTOLD])
   HAVE_STRTOLL=1;            AC_SUBST([HAVE_STRTOLL])
@@ -166,30 +226,41 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   HAVE_SYS_LOADAVG_H=0;      AC_SUBST([HAVE_SYS_LOADAVG_H])
   HAVE_UNLOCKPT=1;           AC_SUBST([HAVE_UNLOCKPT])
   HAVE_DECL_UNSETENV=1;      AC_SUBST([HAVE_DECL_UNSETENV])
+  REPLACE__EXIT=0;           AC_SUBST([REPLACE__EXIT])
+  REPLACE_ABORT=0;           AC_SUBST([REPLACE_ABORT])
   REPLACE_ALIGNED_ALLOC=0;   AC_SUBST([REPLACE_ALIGNED_ALLOC])
   REPLACE_CALLOC_FOR_CALLOC_GNU=0;    AC_SUBST([REPLACE_CALLOC_FOR_CALLOC_GNU])
   REPLACE_CALLOC_FOR_CALLOC_POSIX=0;  AC_SUBST([REPLACE_CALLOC_FOR_CALLOC_POSIX])
   REPLACE_CANONICALIZE_FILE_NAME=0;  AC_SUBST([REPLACE_CANONICALIZE_FILE_NAME])
   REPLACE_FREE=0;            AC_SUBST([REPLACE_FREE])
+  REPLACE_GETLOADAVG=0;      AC_SUBST([REPLACE_GETLOADAVG])
+  REPLACE_GETPROGNAME=0;     AC_SUBST([REPLACE_GETPROGNAME])
+  REPLACE_GETSUBOPT=0;       AC_SUBST([REPLACE_GETSUBOPT])
   REPLACE_INITSTATE=0;       AC_SUBST([REPLACE_INITSTATE])
   REPLACE_MALLOC_FOR_MALLOC_GNU=0;    AC_SUBST([REPLACE_MALLOC_FOR_MALLOC_GNU])
   REPLACE_MALLOC_FOR_MALLOC_POSIX=0;  AC_SUBST([REPLACE_MALLOC_FOR_MALLOC_POSIX])
+  REPLACE_MB_CUR_MAX=0;      AC_SUBST([REPLACE_MB_CUR_MAX])
+  REPLACE_MBSTOWCS=0;        AC_SUBST([REPLACE_MBSTOWCS])
   REPLACE_MBTOWC=0;          AC_SUBST([REPLACE_MBTOWC])
+  REPLACE_MKOSTEMP=0;        AC_SUBST([REPLACE_MKOSTEMP])
+  REPLACE_MKOSTEMPS=0;       AC_SUBST([REPLACE_MKOSTEMPS])
   REPLACE_MKSTEMP=0;         AC_SUBST([REPLACE_MKSTEMP])
   REPLACE_POSIX_MEMALIGN=0;  AC_SUBST([REPLACE_POSIX_MEMALIGN])
+  REPLACE_POSIX_OPENPT=0;    AC_SUBST([REPLACE_POSIX_OPENPT])
   REPLACE_PTSNAME=0;         AC_SUBST([REPLACE_PTSNAME])
   REPLACE_PTSNAME_R=0;       AC_SUBST([REPLACE_PTSNAME_R])
   REPLACE_PUTENV=0;          AC_SUBST([REPLACE_PUTENV])
   REPLACE_QSORT_R=0;         AC_SUBST([REPLACE_QSORT_R])
+  REPLACE_RAND=0;            AC_SUBST([REPLACE_RAND])
   REPLACE_RANDOM=0;          AC_SUBST([REPLACE_RANDOM])
   REPLACE_RANDOM_R=0;        AC_SUBST([REPLACE_RANDOM_R])
-  REPLACE_REALLOC_FOR_REALLOC_GNU=0;    AC_SUBST([REPLACE_REALLOC_FOR_REALLOC_GNU])
   REPLACE_REALLOC_FOR_REALLOC_POSIX=0;  AC_SUBST([REPLACE_REALLOC_FOR_REALLOC_POSIX])
   REPLACE_REALLOCARRAY=0;    AC_SUBST([REPLACE_REALLOCARRAY])
   REPLACE_REALPATH=0;        AC_SUBST([REPLACE_REALPATH])
   REPLACE_SETENV=0;          AC_SUBST([REPLACE_SETENV])
   REPLACE_SETSTATE=0;        AC_SUBST([REPLACE_SETSTATE])
   REPLACE_STRTOD=0;          AC_SUBST([REPLACE_STRTOD])
+  REPLACE_STRTOF=0;          AC_SUBST([REPLACE_STRTOF])
   REPLACE_STRTOL=0;          AC_SUBST([REPLACE_STRTOL])
   REPLACE_STRTOLD=0;         AC_SUBST([REPLACE_STRTOLD])
   REPLACE_STRTOLL=0;         AC_SUBST([REPLACE_STRTOLL])
@@ -197,4 +268,5 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   REPLACE_STRTOULL=0;        AC_SUBST([REPLACE_STRTOULL])
   REPLACE_UNSETENV=0;        AC_SUBST([REPLACE_UNSETENV])
   REPLACE_WCTOMB=0;          AC_SUBST([REPLACE_WCTOMB])
+  CAN_PRINT_STACK_TRACE=0;   AC_SUBST([CAN_PRINT_STACK_TRACE])
 ])
diff --git a/gl/m4/strcasecmp.m4 b/gl/m4/strcasecmp.m4
new file mode 100644
index 00000000..eb4345d9
--- /dev/null
+++ b/gl/m4/strcasecmp.m4
@@ -0,0 +1,67 @@
+# strcasecmp.m4
+# serial 3
+dnl Copyright (C) 2002-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_STRCASECMP],
+[
+  AC_REQUIRE([gl_STRINGS_H_DEFAULTS])
+  AC_CHECK_FUNCS([strcasecmp])
+  if test $ac_cv_func_strcasecmp = yes; then
+    gl_STRCASECMP_WORKS
+    case "$gl_cv_func_strcasecmp_works" in
+      *yes) ;;
+      *) REPLACE_STRCASECMP=1 ;;
+    esac
+  else
+    HAVE_STRCASECMP=0
+  fi
+])
+
+AC_DEFUN([gl_STRCASECMP_WORKS],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_CACHE_CHECK([whether strcasecmp works],
+    [gl_cv_func_strcasecmp_works],
+    [dnl Prepare a guess, used when cross-compiling or when specific locales
+     dnl are not available.
+     case "$host_os" in
+       solaris* | cygwin*)
+         gl_cv_func_strcasecmp_works="guessing no" ;;
+       *)
+         gl_cv_func_strcasecmp_works="guessing yes" ;;
+     esac
+     AC_RUN_IFELSE(
+       [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+int main ()
+{
+  if (setlocale (LC_ALL, "fr_FR.ISO-8859-1") != NULL
+      || setlocale (LC_ALL, "fr_FR.ISO8859-1") != NULL)
+    {
+      int c1 = (unsigned char) '\311';
+      int c2 = (unsigned char) '\351';
+      if (tolower (c1) == c2 && toupper (c2) == c1)
+        return strcasecmp ("Fej\311r", "Fej\351r") != 0;
+    }
+  return 2;
+}]])],
+       [gl_cv_func_strcasecmp_works=yes],
+       [if test $? = 1; then
+          gl_cv_func_strcasecmp_works=no
+        fi
+       ],
+       [:])
+    ])
+])
+
+# Prerequisites of lib/strcasecmp.c.
+AC_DEFUN([gl_PREREQ_STRCASECMP], [
+  :
+])
diff --git a/gl/m4/strcasestr.m4 b/gl/m4/strcasestr.m4
index 971e0b23..eb2862f1 100644
--- a/gl/m4/strcasestr.m4
+++ b/gl/m4/strcasestr.m4
@@ -1,8 +1,10 @@
-# strcasestr.m4 serial 28
-dnl Copyright (C) 2005, 2007-2023 Free Software Foundation, Inc.
+# strcasestr.m4
+# serial 29
+dnl Copyright (C) 2005, 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Check that strcasestr is present and works.
 AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE],
@@ -97,7 +99,7 @@ static void quit (int sig) { _exit (sig + 128); }
     char *haystack = (char *) malloc (2 * m + 2);
     char *needle = (char *) malloc (m + 2);
     /* Failure to compile this test due to missing alarm is okay,
-       since all such platforms (mingw) also lack strcasestr.  */
+       since all such platforms (mingw, MSVC) also lack strcasestr.  */
     signal (SIGALRM, quit);
     alarm (5);
     /* Check for quadratic performance.  */
diff --git a/gl/m4/strerror.m4 b/gl/m4/strerror.m4
index 8879eb08..c8b3b207 100644
--- a/gl/m4/strerror.m4
+++ b/gl/m4/strerror.m4
@@ -1,8 +1,10 @@
-# strerror.m4 serial 23
-dnl Copyright (C) 2002, 2007-2023 Free Software Foundation, Inc.
+# strerror.m4
+# serial 25
+dnl Copyright (C) 2002, 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_STRERROR],
 [
@@ -24,12 +26,12 @@ AC_DEFUN([gl_FUNC_STRERROR],
         [gl_cv_func_working_strerror=yes],
         [gl_cv_func_working_strerror=no],
         [case "$host_os" in
-                          # Guess yes on glibc systems.
-           *-gnu* | gnu*) gl_cv_func_working_strerror="guessing yes" ;;
-                          # Guess yes on musl systems.
-           *-musl*)       gl_cv_func_working_strerror="guessing yes" ;;
-                          # If we don't know, obey --enable-cross-guesses.
-           *)             gl_cv_func_working_strerror="$gl_cross_guess_normal" ;;
+                               # Guess yes on glibc systems.
+           *-gnu* | gnu*)      gl_cv_func_working_strerror="guessing yes" ;;
+                               # Guess yes on musl systems.
+           *-musl* | midipix*) gl_cv_func_working_strerror="guessing yes" ;;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_working_strerror="$gl_cross_guess_normal" ;;
          esac
         ])
     ])
@@ -80,14 +82,14 @@ AC_DEFUN([gl_FUNC_STRERROR_0],
       [gl_cv_func_strerror_0_works=yes],
       [gl_cv_func_strerror_0_works=no],
       [case "$host_os" in
-                        # Guess yes on glibc systems.
-         *-gnu* | gnu*) gl_cv_func_strerror_0_works="guessing yes" ;;
-                        # Guess yes on musl systems.
-         *-musl*)       gl_cv_func_strerror_0_works="guessing yes" ;;
-                        # Guess yes on native Windows.
-         mingw*)        gl_cv_func_strerror_0_works="guessing yes" ;;
-                        # If we don't know, obey --enable-cross-guesses.
-         *)             gl_cv_func_strerror_0_works="$gl_cross_guess_normal" ;;
+                             # Guess yes on glibc systems.
+         *-gnu* | gnu*)      gl_cv_func_strerror_0_works="guessing yes" ;;
+                             # Guess yes on musl systems.
+         *-musl* | midipix*) gl_cv_func_strerror_0_works="guessing yes" ;;
+                             # Guess yes on native Windows.
+         mingw* | windows*)  gl_cv_func_strerror_0_works="guessing yes" ;;
+                             # If we don't know, obey --enable-cross-guesses.
+         *)                  gl_cv_func_strerror_0_works="$gl_cross_guess_normal" ;;
        esac
       ])
   ])
diff --git a/gl/m4/string_h.m4 b/gl/m4/string_h.m4
index 5da3cc25..fc73603a 100644
--- a/gl/m4/string_h.m4
+++ b/gl/m4/string_h.m4
@@ -1,11 +1,12 @@
-# Configure a GNU-like replacement for <string.h>.
-
-# Copyright (C) 2007-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# string_h.m4
+# serial 44.1
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# serial 35
+# Configure a GNU-like replacement for <string.h>.
 
 # Written by Paul Eggert.
 
@@ -23,8 +24,9 @@ AC_DEFUN_ONCE([gl_STRING_H],
     ]],
     [explicit_bzero ffsl ffsll memmem mempcpy memrchr memset_explicit
      rawmemchr stpcpy stpncpy strchrnul
-     strdup strncat strndup strnlen strpbrk strsep strcasestr strtok_r
-     strerror_r strerrorname_np sigabbrev_np sigdescr_np strsignal strverscmp])
+     strdup strncat strncpy strndup strnlen strpbrk strsep strcasestr strtok_r
+     strerror_l strerror_r strerrorname_np
+     sigabbrev_np sigdescr_np strsignal strverscmp])
 
   AC_REQUIRE([AC_C_RESTRICT])
 ])
@@ -62,6 +64,7 @@ AC_DEFUN([gl_STRING_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRCHRNUL])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRDUP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNCAT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNCPY])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNDUP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNLEN])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRPBRK])
@@ -69,6 +72,8 @@ AC_DEFUN([gl_STRING_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRSTR])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRCASESTR])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRTOK_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STR_STARTSWITH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STR_ENDSWITH])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSLEN])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSNLEN])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSCHR])
@@ -83,8 +88,11 @@ AC_DEFUN([gl_STRING_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSSPN])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSSEP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSTOK_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBS_STARTSWITH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBS_ENDSWITH])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRERROR])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRERROR_R])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRERROR_L])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRERRORNAME_NP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGABBREV_NP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SIGDESCR_NP])
@@ -123,6 +131,7 @@ AC_DEFUN([gl_STRING_H_DEFAULTS],
   HAVE_STRCASESTR=1;            AC_SUBST([HAVE_STRCASESTR])
   HAVE_DECL_STRTOK_R=1;         AC_SUBST([HAVE_DECL_STRTOK_R])
   HAVE_DECL_STRERROR_R=1;       AC_SUBST([HAVE_DECL_STRERROR_R])
+  HAVE_STRERROR_L=1;            AC_SUBST([HAVE_STRERROR_L])
   HAVE_STRERRORNAME_NP=1;       AC_SUBST([HAVE_STRERRORNAME_NP])
   HAVE_SIGABBREV_NP=1;          AC_SUBST([HAVE_SIGABBREV_NP])
   HAVE_SIGDESCR_NP=1;           AC_SUBST([HAVE_SIGDESCR_NP])
@@ -131,10 +140,14 @@ AC_DEFUN([gl_STRING_H_DEFAULTS],
   REPLACE_FFSLL=0;              AC_SUBST([REPLACE_FFSLL])
   REPLACE_MEMCHR=0;             AC_SUBST([REPLACE_MEMCHR])
   REPLACE_MEMMEM=0;             AC_SUBST([REPLACE_MEMMEM])
+  REPLACE_MEMPCPY=0;            AC_SUBST([REPLACE_MEMPCPY])
+  REPLACE_MEMSET_EXPLICIT=0;    AC_SUBST([REPLACE_MEMSET_EXPLICIT])
+  REPLACE_STPCPY=0;             AC_SUBST([REPLACE_STPCPY])
   REPLACE_STPNCPY=0;            AC_SUBST([REPLACE_STPNCPY])
   REPLACE_STRCHRNUL=0;          AC_SUBST([REPLACE_STRCHRNUL])
   REPLACE_STRDUP=0;             AC_SUBST([REPLACE_STRDUP])
   REPLACE_STRNCAT=0;            AC_SUBST([REPLACE_STRNCAT])
+  REPLACE_STRNCPY=0;            AC_SUBST([REPLACE_STRNCPY])
   REPLACE_STRNDUP=0;            AC_SUBST([REPLACE_STRNDUP])
   REPLACE_STRNLEN=0;            AC_SUBST([REPLACE_STRNLEN])
   REPLACE_STRSTR=0;             AC_SUBST([REPLACE_STRSTR])
@@ -142,7 +155,9 @@ AC_DEFUN([gl_STRING_H_DEFAULTS],
   REPLACE_STRTOK_R=0;           AC_SUBST([REPLACE_STRTOK_R])
   REPLACE_STRERROR=0;           AC_SUBST([REPLACE_STRERROR])
   REPLACE_STRERROR_R=0;         AC_SUBST([REPLACE_STRERROR_R])
+  REPLACE_STRERROR_L=0;         AC_SUBST([REPLACE_STRERROR_L])
   REPLACE_STRERRORNAME_NP=0;    AC_SUBST([REPLACE_STRERRORNAME_NP])
   REPLACE_STRSIGNAL=0;          AC_SUBST([REPLACE_STRSIGNAL])
+  REPLACE_STRVERSCMP=0;         AC_SUBST([REPLACE_STRVERSCMP])
   UNDEFINE_STRTOK_R=0;          AC_SUBST([UNDEFINE_STRTOK_R])
 ])
diff --git a/gl/m4/strings_h.m4 b/gl/m4/strings_h.m4
index 4c41221b..18f30d4a 100644
--- a/gl/m4/strings_h.m4
+++ b/gl/m4/strings_h.m4
@@ -1,10 +1,12 @@
-# Configure a replacement for <strings.h>.
-# serial 9
+# strings_h.m4
+# serial 14
+dnl Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# Configure a replacement for <strings.h>.
 
 AC_DEFUN_ONCE([gl_STRINGS_H],
 [
@@ -27,7 +29,7 @@ AC_DEFUN_ONCE([gl_STRINGS_H],
        <strings.h>.  */
     #include <sys/types.h>
     #include <strings.h>
-    ]], [ffs strcasecmp strncasecmp])
+    ]], [ffs strcasecmp strcasecmp_l strncasecmp strncasecmp_l])
 ])
 
 # gl_STRINGS_MODULE_INDICATOR([modulename])
@@ -48,6 +50,10 @@ AC_DEFUN([gl_STRINGS_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_STRINGS_H_MODULE_INDICATOR_DEFAULTS], [
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_FFS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRCASECMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRCASECMP_L])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNCASECMP])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRNCASECMP_L])
   ])
   m4_require(GL_MODULE_INDICATOR_PREFIX[_STRINGS_H_MODULE_INDICATOR_DEFAULTS])
   AC_REQUIRE([gl_STRINGS_H_DEFAULTS])
@@ -58,5 +64,12 @@ AC_DEFUN([gl_STRINGS_H_DEFAULTS],
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_FFS=1;              AC_SUBST([HAVE_FFS])
   HAVE_STRCASECMP=1;       AC_SUBST([HAVE_STRCASECMP])
+  HAVE_STRCASECMP_L=1;     AC_SUBST([HAVE_STRCASECMP_L])
+  HAVE_STRNCASECMP=1;      AC_SUBST([HAVE_STRNCASECMP])
+  HAVE_STRNCASECMP_L=1;    AC_SUBST([HAVE_STRNCASECMP_L])
   HAVE_DECL_STRNCASECMP=1; AC_SUBST([HAVE_DECL_STRNCASECMP])
+  REPLACE_STRCASECMP=0;    AC_SUBST([REPLACE_STRCASECMP])
+  REPLACE_STRCASECMP_L=0;  AC_SUBST([REPLACE_STRCASECMP_L])
+  REPLACE_STRNCASECMP=0;   AC_SUBST([REPLACE_STRNCASECMP])
+  REPLACE_STRNCASECMP_L=0; AC_SUBST([REPLACE_STRNCASECMP_L])
 ])
diff --git a/gl/m4/strcase.m4 b/gl/m4/strncasecmp.m4
index 3cf740d2..c7c8b240 100644
--- a/gl/m4/strcase.m4
+++ b/gl/m4/strncasecmp.m4
@@ -1,30 +1,22 @@
-# strcase.m4 serial 12
-dnl Copyright (C) 2002, 2005-2023 Free Software Foundation, Inc.
+# strncasecmp.m4
+# serial 2
+dnl Copyright (C) 2002-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
-
-AC_DEFUN([gl_STRCASE],
-[
-  gl_FUNC_STRCASECMP
-  gl_FUNC_STRNCASECMP
-])
-
-AC_DEFUN([gl_FUNC_STRCASECMP],
-[
-  AC_REQUIRE([gl_STRINGS_H_DEFAULTS])
-  AC_CHECK_FUNCS([strcasecmp])
-  if test $ac_cv_func_strcasecmp = no; then
-    HAVE_STRCASECMP=0
-  fi
-])
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_STRNCASECMP],
 [
   AC_REQUIRE([gl_STRINGS_H_DEFAULTS])
   AC_CHECK_FUNCS([strncasecmp])
   if test $ac_cv_func_strncasecmp = yes; then
-    HAVE_STRNCASECMP=1
+    dnl Assume that strncasecmp and strcasecmp share the same bugs.
+    gl_STRCASECMP_WORKS
+    case "$gl_cv_func_strcasecmp_works" in
+      *yes) ;;
+      *) REPLACE_STRNCASECMP=1 ;;
+    esac
   else
     HAVE_STRNCASECMP=0
   fi
@@ -34,11 +26,6 @@ AC_DEFUN([gl_FUNC_STRNCASECMP],
   fi
 ])
 
-# Prerequisites of lib/strcasecmp.c.
-AC_DEFUN([gl_PREREQ_STRCASECMP], [
-  :
-])
-
 # Prerequisites of lib/strncasecmp.c.
 AC_DEFUN([gl_PREREQ_STRNCASECMP], [
   :
diff --git a/gl/m4/strncpy.m4 b/gl/m4/strncpy.m4
new file mode 100644
index 00000000..57876171
--- /dev/null
+++ b/gl/m4/strncpy.m4
@@ -0,0 +1,94 @@
+# strncpy.m4
+# serial 1
+dnl Copyright (C) 2002-2004, 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_FUNC_STRNCPY],
+[
+  AC_REQUIRE([gl_STRING_H_DEFAULTS])
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  dnl Check for prerequisites for memory fence checks.
+  gl_FUNC_MMAP_ANON
+  AC_CHECK_HEADERS_ONCE([sys/mman.h])
+  AC_CHECK_FUNCS_ONCE([mprotect])
+
+  dnl Detect bug in FreeBSD 15.0 on x86_64:
+  dnl strncpy should not dereference more than n bytes, but always dereferences
+  dnl n+1 bytes if the first n bytes don't contain a NUL byte.
+  dnl Assume that strncpy works on platforms that lack mprotect.
+  AC_CACHE_CHECK([whether strncpy works], [gl_cv_func_strncpy_works],
+    [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <string.h>
+#if HAVE_SYS_MMAN_H
+# include <fcntl.h>
+# include <unistd.h>
+# include <sys/types.h>
+# include <sys/mman.h>
+#endif
+]GL_MDA_DEFINES],
+[[
+  char *fence = NULL;
+#if HAVE_SYS_MMAN_H && HAVE_MPROTECT
+  {
+    long int pagesize = sysconf (_SC_PAGESIZE);
+    char *two_pages =
+      (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE,
+                     MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+    if (two_pages != (char *)(-1)
+        && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0)
+      fence = two_pages + pagesize;
+  }
+#endif
+  if (fence)
+    {
+      char dest[8];
+
+      dest[0] = 'a';
+      dest[1] = 'b';
+      dest[2] = 'c';
+      dest[3] = 'd';
+      dest[4] = 'e';
+      dest[5] = 'f';
+      dest[6] = 'g';
+
+      *(fence - 3) = '7';
+      *(fence - 2) = '2';
+      *(fence - 1) = '9';
+
+      if (strncpy (dest + 1, fence - 3, 3) != dest + 1)
+        return 1;
+      if (dest[0] != 'a')
+        return 2;
+      if (dest[1] != '7' || dest[2] != '2' || dest[3] != '9')
+        return 3;
+      if (dest[4] != 'e')
+        return 4;
+    }
+  return 0;
+]])], [gl_cv_func_strncpy_works=yes], [gl_cv_func_strncpy_works=no],
+       [
+        case "$host_os" in
+                                 # Guess no on FreeBSD.
+          freebsd* | dragonfly*) gl_cv_func_strncpy_works="guessing no" ;;
+                                 # Guess yes on native Windows.
+          mingw* | windows*)     gl_cv_func_strncpy_works="guessing yes" ;;
+                                 # Guess yes otherwise.
+          *)                     gl_cv_func_strncpy_works="guessing yes" ;;
+        esac
+       ])
+    ])
+  case "$gl_cv_func_strncpy_works" in
+    *yes) ;;
+    *) REPLACE_STRNCPY=1 ;;
+  esac
+])
+
+# Prerequisites of lib/strncpy.c.
+AC_DEFUN([gl_PREREQ_STRNCPY], [
+  :
+])
diff --git a/gl/m4/strsep.m4 b/gl/m4/strsep.m4
index e0da09a3..b018ff88 100644
--- a/gl/m4/strsep.m4
+++ b/gl/m4/strsep.m4
@@ -1,8 +1,10 @@
-# strsep.m4 serial 11
-dnl Copyright (C) 2002-2004, 2007, 2009-2023 Free Software Foundation, Inc.
+# strsep.m4
+# serial 11
+dnl Copyright (C) 2002-2004, 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_STRSEP],
 [
diff --git a/gl/m4/strstr.m4 b/gl/m4/strstr.m4
index 7de203a7..1b5ef6c1 100644
--- a/gl/m4/strstr.m4
+++ b/gl/m4/strstr.m4
@@ -1,8 +1,10 @@
-# strstr.m4 serial 24
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# strstr.m4
+# serial 25
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Check that strstr works.
 AC_DEFUN([gl_FUNC_STRSTR_SIMPLE],
@@ -94,7 +96,7 @@ static void quit (int sig) { _exit (sig + 128); }
     char *haystack = (char *) malloc (2 * m + 2);
     char *needle = (char *) malloc (m + 2);
     /* Failure to compile this test due to missing alarm is okay,
-       since all such platforms (mingw) also have quadratic strstr.  */
+       since all such platforms (mingw, MSVC) also have quadratic strstr.  */
     signal (SIGALRM, quit);
     alarm (5);
     /* Check for quadratic performance.  */
diff --git a/gl/m4/sys_cdefs_h.m4 b/gl/m4/sys_cdefs_h.m4
new file mode 100644
index 00000000..d72796ca
--- /dev/null
+++ b/gl/m4/sys_cdefs_h.m4
@@ -0,0 +1,26 @@
+# sys_cdefs_h.m4 - Is <sys/cdefs.h> compatible enough with glibc?
+# serial 2
+dnl Copyright 2024-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl Written by Paul Eggert.
+
+AC_DEFUN_ONCE([gl_CHECK_HEADER_SYS_CDEFS_H],
+  [AC_CACHE_CHECK([for glibc-compatible sys/cdefs.h],
+     [gl_cv_header_sys_cdefs_h],
+     [AC_COMPILE_IFELSE(
+        [AC_LANG_DEFINES_PROVIDED
+         [#include <sys/cdefs.h>
+          enum { foo = __GNUC_PREREQ (14, 1) } bar;
+        ]],
+        [gl_cv_header_sys_cdefs_h=yes],
+        [gl_cv_header_sys_cdefs_h=no])])
+   if test "$gl_cv_header_sys_cdefs_h" = yes; then
+     HAVE_SYS_CDEFS_H=1
+   else
+     HAVE_SYS_CDEFS_H=0
+   fi
+   AC_SUBST([HAVE_SYS_CDEFS_H])])
diff --git a/gl/m4/sys_socket_h.m4 b/gl/m4/sys_socket_h.m4
index 98a10416..fb69209b 100644
--- a/gl/m4/sys_socket_h.m4
+++ b/gl/m4/sys_socket_h.m4
@@ -1,8 +1,10 @@
-# sys_socket_h.m4 serial 29
-dnl Copyright (C) 2005-2023 Free Software Foundation, Inc.
+# sys_socket_h.m4
+# serial 31
+dnl Copyright (C) 2005-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Simon Josefsson.
 
@@ -51,24 +53,10 @@ AC_DEFUN_ONCE([gl_SYS_SOCKET_H],
   fi
   # We need to check for ws2tcpip.h now.
   gl_PREREQ_SYS_H_SOCKET
-  AC_CHECK_TYPES([struct sockaddr_storage, sa_family_t],,,[
-  /* sys/types.h is not needed according to POSIX, but the
-     sys/socket.h in i386-unknown-freebsd4.10 and
-     powerpc-apple-darwin5.5 required it. */
-#include <sys/types.h>
-#ifdef HAVE_SYS_SOCKET_H
-#include <sys/socket.h>
-#endif
-#ifdef HAVE_WS2TCPIP_H
-#include <ws2tcpip.h>
-#endif
-])
+  gl_PREREQ_SYS_SA_FAMILY
   if test $ac_cv_type_struct_sockaddr_storage = no; then
     HAVE_STRUCT_SOCKADDR_STORAGE=0
   fi
-  if test $ac_cv_type_sa_family_t = no; then
-    HAVE_SA_FAMILY_T=0
-  fi
   if test $ac_cv_type_struct_sockaddr_storage != no; then
     AC_CHECK_MEMBERS([struct sockaddr_storage.ss_family],
       [],
@@ -157,6 +145,32 @@ AC_DEFUN([gl_PREREQ_SYS_H_WS2TCPIP],
   AC_SUBST([HAVE_WS2TCPIP_H])
 ])
 
+# Common prerequisites of the <sys/socket.h> replacement and of the <sys/un.h>
+# replacement.
+# Sets and substitutes HAVE_SA_FAMILY_T.
+AC_DEFUN([gl_PREREQ_SYS_SA_FAMILY],
+[
+  AC_REQUIRE([gl_CHECK_SOCKET_HEADERS])
+  AC_CHECK_TYPES([struct sockaddr_storage, sa_family_t],,,[
+  /* sys/types.h is not needed according to POSIX, but the
+     sys/socket.h in i386-unknown-freebsd4.10 and
+     powerpc-apple-darwin5.5 required it. */
+#include <sys/types.h>
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_WS2TCPIP_H
+#include <ws2tcpip.h>
+#endif
+])
+  if test $ac_cv_type_sa_family_t = yes; then
+    HAVE_SA_FAMILY_T=1
+  else
+    HAVE_SA_FAMILY_T=0
+  fi
+  AC_SUBST([HAVE_SA_FAMILY_T])
+])
+
 # gl_SYS_SOCKET_MODULE_INDICATOR([modulename])
 # sets the shell variable that indicates the presence of the given module
 # to a C preprocessor expression that will evaluate to 1.
@@ -201,6 +215,5 @@ AC_DEFUN([gl_SYS_SOCKET_H_DEFAULTS],
   HAVE_STRUCT_SOCKADDR_STORAGE=1; AC_SUBST([HAVE_STRUCT_SOCKADDR_STORAGE])
   HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY=1;
                         AC_SUBST([HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY])
-  HAVE_SA_FAMILY_T=1;   AC_SUBST([HAVE_SA_FAMILY_T])
   HAVE_ACCEPT4=1;       AC_SUBST([HAVE_ACCEPT4])
 ])
diff --git a/gl/m4/sys_stat_h.m4 b/gl/m4/sys_stat_h.m4
index ca57398a..fdcc8954 100644
--- a/gl/m4/sys_stat_h.m4
+++ b/gl/m4/sys_stat_h.m4
@@ -1,8 +1,10 @@
-# sys_stat_h.m4 serial 42   -*- Autoconf -*-
-dnl Copyright (C) 2006-2023 Free Software Foundation, Inc.
+# sys_stat_h.m4
+# serial 42   -*- Autoconf -*-
+dnl Copyright (C) 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Eric Blake.
 dnl Provide a GNU-like <sys/stat.h>.
diff --git a/gl/m4/sys_types_h.m4 b/gl/m4/sys_types_h.m4
index 627671fb..e99fdcc6 100644
--- a/gl/m4/sys_types_h.m4
+++ b/gl/m4/sys_types_h.m4
@@ -1,8 +1,10 @@
-# sys_types_h.m4 serial 13
-dnl Copyright (C) 2011-2023 Free Software Foundation, Inc.
+# sys_types_h.m4
+# serial 15
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_SYS_TYPES_H],
 [
@@ -22,6 +24,9 @@ AC_DEFUN_ONCE([gl_SYS_TYPES_H],
   dnl Whether to override the 'off_t' type.
   AC_REQUIRE([gl_TYPE_OFF_T])
 
+  dnl Whether to define the 'off64_t' type.
+  AC_REQUIRE([gl_TYPE_OFF64_T])
+
   dnl Whether to override the 'dev_t' and 'ino_t' types.
   m4_ifdef([gl_WINDOWS_STAT_INODES], [
     AC_REQUIRE([gl_WINDOWS_STAT_INODES])
@@ -29,6 +34,14 @@ AC_DEFUN_ONCE([gl_SYS_TYPES_H],
     WINDOWS_STAT_INODES=0
   ])
   AC_SUBST([WINDOWS_STAT_INODES])
+
+  dnl Test whether the 'blksize_t' type is defined.
+  AC_CHECK_TYPE([blksize_t], [HAVE_BLKSIZE_T=1], [HAVE_BLKSIZE_T=0])
+  AC_SUBST([HAVE_BLKSIZE_T])
+
+  dnl Test whether the 'blkcnt_t' type is defined.
+  AC_CHECK_TYPE([blkcnt_t], [HAVE_BLKCNT_T=1], [HAVE_BLKCNT_T=0])
+  AC_SUBST([HAVE_BLKCNT_T])
 ])
 
 # Initializes the default values for AC_SUBSTed shell variables.
diff --git a/gl/m4/sys_uio_h.m4 b/gl/m4/sys_uio_h.m4
index 93a65d26..eb0e8424 100644
--- a/gl/m4/sys_uio_h.m4
+++ b/gl/m4/sys_uio_h.m4
@@ -1,8 +1,10 @@
-# sys_uio_h.m4 serial 3
-dnl Copyright (C) 2011-2023 Free Software Foundation, Inc.
+# sys_uio_h.m4
+# serial 3
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_SYS_UIO_H],
 [
diff --git a/gl/m4/threadlib.m4 b/gl/m4/threadlib.m4
index b536b047..333c8fe0 100644
--- a/gl/m4/threadlib.m4
+++ b/gl/m4/threadlib.m4
@@ -1,8 +1,10 @@
-# threadlib.m4 serial 32a
-dnl Copyright (C) 2005-2023 Free Software Foundation, Inc.
+# threadlib.m4
+# serial 45.1
+dnl Copyright (C) 2005-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 
@@ -55,24 +57,22 @@ AC_DEFUN([gl_ANYTHREADLIB_EARLY],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
   if test -z "$gl_anythreadlib_early_done"; then
-    case "$host_os" in
-      osf*)
-        # On OSF/1, the compiler needs the flag -D_REENTRANT so that it
+    AS_CASE([$host_os],
+      [osf*],
+       [# On OSF/1, the compiler needs the flag -D_REENTRANT so that it
         # groks <pthread.h>. cc also understands the flag -pthread, but
-        # we don't use it because 1. gcc-2.95 doesn't understand -pthread,
+        # we do not use it because 1. gcc-2.95 does not understand -pthread,
         # 2. putting a flag into CPPFLAGS that has an effect on the linker
         # causes the AC_LINK_IFELSE test below to succeed unexpectedly,
         # leading to wrong values of LIBTHREAD and LTLIBTHREAD.
         CPPFLAGS="$CPPFLAGS -D_REENTRANT"
-        ;;
-    esac
+       ])
     # Some systems optimize for single-threaded programs by default, and
     # need special flags to disable these optimizations. For example, the
-    # definition of 'errno' in <errno.h>.
-    case "$host_os" in
-      aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;;
-      solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;;
-    esac
+    # definition of errno in <errno.h>.
+    AS_CASE([$host_os],
+      [aix* | freebsd*], [CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE"],
+      [hpux* | solaris*], [CPPFLAGS="$CPPFLAGS -D_REENTRANT"])
     gl_anythreadlib_early_done=done
   fi
 ])
@@ -84,23 +84,26 @@ AC_DEFUN([gl_WEAK_SYMBOLS],
   AC_REQUIRE([AC_CANONICAL_HOST])
   AC_CACHE_CHECK([whether imported symbols can be declared weak],
     [gl_cv_have_weak],
-    [case "$host_os" in
-       cygwin*)
-         dnl On Cygwin 3.2.0 with gcc 10.2, the test below would succeed, but
-         dnl programs that use pthread_in_use() with weak symbol references
-         dnl crash miserably at runtime.
+    [AS_CASE([$host_os],
+       [cygwin* | mingw* | windows*],
+        [
+         dnl On Cygwin 3.2.0 with gcc 10.2, and likewise on mingw 10.0.0 with
+         dnl gcc 11.3, the test below would succeed, but programs that use
+         dnl pthread_in_use() with weak symbol references crash miserably at
+         dnl runtime.
          gl_cv_have_weak="guessing no"
-         ;;
-       *)
+        ],
+        [
          gl_cv_have_weak=no
          dnl First, test whether the compiler accepts it syntactically.
          AC_LINK_IFELSE(
            [AC_LANG_PROGRAM(
               [[extern void xyzzy ();
-#pragma weak xyzzy]],
+#pragma weak xyzzy
+              ]],
               [[xyzzy();]])],
            [gl_cv_have_weak=maybe])
-         if test $gl_cv_have_weak = maybe; then
+         AS_IF([test $gl_cv_have_weak = maybe], [
            dnl Second, test whether it actually works. On Cygwin 1.7.2, with
            dnl gcc 4.3, symbols declared weak always evaluate to the address 0.
            AC_RUN_IFELSE(
@@ -123,20 +126,19 @@ int main ()
                 [gl_cv_have_weak="guessing yes"],
                 [gl_cv_have_weak="guessing no"])
              ])
-         fi
-         ;;
-     esac
-     dnl But when linking statically, weak symbols don't work.
-     case " $LDFLAGS " in
-       *" -static "*) gl_cv_have_weak=no ;;
-     esac
+         ])
+        ])
+     dnl But when linking statically, weak symbols do not work.
+     AS_CASE([" $LDFLAGS "],
+       [*" -static "*], [gl_cv_have_weak=no])
      dnl Test for a bug in FreeBSD 11: A link error occurs when using a weak
      dnl symbol and linking against a shared library that has a dependency on
      dnl the shared library that defines the symbol.
-     case "$gl_cv_have_weak" in
-       *yes)
-         case "$host_os" in
-           freebsd* | dragonfly* | midnightbsd*)
+     AS_CASE([$gl_cv_have_weak],
+       [*yes],
+        [AS_CASE([$host_os],
+           [freebsd* | dragonfly* | midnightbsd*],
+            [
              : > conftest1.c
              $CC $CPPFLAGS $CFLAGS $LDFLAGS -fPIC -shared -o libempty.so conftest1.c -lpthread >&AS_MESSAGE_LOG_FD 2>&1
              cat <<EOF > conftest2.c
@@ -150,17 +152,15 @@ EOF
              $CC $CPPFLAGS $CFLAGS $LDFLAGS -o conftest conftest2.c libempty.so >&AS_MESSAGE_LOG_FD 2>&1 \
                || gl_cv_have_weak=no
              rm -f conftest1.c libempty.so conftest2.c conftest
-             ;;
-         esac
-         ;;
-     esac
+            ])
+        ])
     ])
-  case "$gl_cv_have_weak" in
-    *yes)
+  AS_CASE([$gl_cv_have_weak],
+    [*yes],
+     [
       AC_DEFINE([HAVE_WEAK_SYMBOLS], [1],
         [Define to 1 if the compiler and linker support weak declarations of symbols.])
-      ;;
-  esac
+     ])
 ])
 
 dnl ============================================================================
@@ -174,7 +174,7 @@ dnl Sets the variable LIBPMULTITHREAD, for programs that really need
 dnl multithread functionality. The difference between LIBPTHREAD and
 dnl LIBPMULTITHREAD is that on platforms supporting weak symbols, typically
 dnl LIBPTHREAD is empty whereas LIBPMULTITHREAD is not.
-dnl Sets the variable LIB_SCHED_YIELD to the linker options needed to use the
+dnl Sets the variable SCHED_YIELD_LIB to the linker options needed to use the
 dnl sched_yield() function.
 dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
 dnl multithread-safe programs.
@@ -186,15 +186,15 @@ dnl The guts of gl_PTHREADLIB. Needs to be expanded only once.
 AC_DEFUN([gl_PTHREADLIB_BODY],
 [
   AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
-  if test -z "$gl_pthreadlib_body_done"; then
+  AS_IF([test -z "$gl_pthreadlib_body_done"], [
     gl_pthread_api=no
     LIBPTHREAD=
     LIBPMULTITHREAD=
     # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
-    # it groks <pthread.h>. It's added above, in gl_ANYTHREADLIB_EARLY.
+    # it groks <pthread.h>. It is added above, in gl_ANYTHREADLIB_EARLY.
     AC_CHECK_HEADER([pthread.h],
       [gl_have_pthread_h=yes], [gl_have_pthread_h=no])
-    if test "$gl_have_pthread_h" = yes; then
+    AS_IF([test "$gl_have_pthread_h" = yes], [
       # Other possible tests:
       #   -lpthreads (FSU threads, PCthreads)
       #   -lgthreads
@@ -205,8 +205,8 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
       # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04
       # needs -pthread for some reason.  See:
       # https://lists.gnu.org/r/bug-gnulib/2014-09/msg00023.html
-      save_LIBS=$LIBS
-      for gl_pthread in '' '-pthread'; do
+      saved_LIBS="$LIBS"
+      for gl_pthread in "" "-pthread"; do
         LIBS="$LIBS $gl_pthread"
         AC_LINK_IFELSE(
           [AC_LANG_PROGRAM(
@@ -219,7 +219,7 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
           [gl_pthread_api=yes
            LIBPTHREAD=$gl_pthread
            LIBPMULTITHREAD=$gl_pthread])
-        LIBS=$save_LIBS
+        LIBS="$saved_LIBS"
         test $gl_pthread_api = yes && break
       done
       echo "$as_me:__oline__: gl_pthread_api=$gl_pthread_api" >&AS_MESSAGE_LOG_FD
@@ -228,8 +228,9 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
       gl_pthread_in_glibc=no
       # On Linux with glibc >= 2.34, libc contains the fully functional
       # pthread functions.
-      case "$host_os" in
-        linux*)
+      AS_CASE([$host_os],
+        [linux*],
+         [
           AC_EGREP_CPP([Lucky user],
             [#include <features.h>
              #ifdef __GNU_LIBRARY__
@@ -240,19 +241,18 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
             ],
             [gl_pthread_in_glibc=yes],
             [])
-          ;;
-      esac
+         ])
       echo "$as_me:__oline__: gl_pthread_in_glibc=$gl_pthread_in_glibc" >&AS_MESSAGE_LOG_FD
 
       # Test for libpthread by looking for pthread_kill. (Not pthread_self,
       # since it is defined as a macro on OSF/1.)
-      if test $gl_pthread_api = yes && test -z "$LIBPTHREAD"; then
+      AS_IF([test $gl_pthread_api = yes && test -z "$LIBPTHREAD"], [
         # The program links fine without libpthread. But it may actually
         # need to link with libpthread in order to create multiple threads.
         AC_CHECK_LIB([pthread], [pthread_kill],
-          [if test $gl_pthread_in_glibc = yes; then
+          [AS_IF([test $gl_pthread_in_glibc = yes], [
              LIBPMULTITHREAD=
-           else
+           ], [
              LIBPMULTITHREAD=-lpthread
              # On Solaris and HP-UX, most pthread functions exist also in libc.
              # Therefore pthread_in_use() needs to actually try to create a
@@ -260,56 +260,68 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
              # pthread_create will actually create a thread.
              # On Solaris 10 or newer, this test is no longer needed, because
              # libc contains the fully functional pthread functions.
-             case "$host_os" in
-changequote(,)dnl
-               solaris | solaris2.[1-9] | solaris2.[1-9].* | hpux*)
-changequote([,])dnl
-                 AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
-                   [Define if the pthread_in_use() detection is hard.])
-             esac
-           fi
+             AS_CASE([$host_os],
+              [[solaris | solaris2.[1-9] | solaris2.[1-9].* | hpux*]],
+               [
+                AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
+                  [Define if the pthread_in_use() detection is hard.])
+               ])
+           ])
+          ],
+          [dnl This is needed on FreeBSD 5.2.1.
+           AC_CHECK_LIB([thr], [pthread_kill],
+             [if test $gl_pthread_in_glibc = yes; then
+                LIBPMULTITHREAD=
+              else
+                LIBPMULTITHREAD=-lthr
+              fi
+             ])
           ])
-      elif test $gl_pthread_api != yes; then
+      ], [test $gl_pthread_api != yes], [
         # Some library is needed. Try libpthread and libc_r.
         AC_CHECK_LIB([pthread], [pthread_kill],
           [gl_pthread_api=yes
            LIBPTHREAD=-lpthread
            LIBPMULTITHREAD=-lpthread])
-        if test $gl_pthread_api != yes; then
+        AS_IF([test $gl_pthread_api != yes], [
           # For FreeBSD 4.
           AC_CHECK_LIB([c_r], [pthread_kill],
             [gl_pthread_api=yes
              LIBPTHREAD=-lc_r
              LIBPMULTITHREAD=-lc_r])
-        fi
-      fi
+        ])
+      ])
       echo "$as_me:__oline__: LIBPMULTITHREAD=$LIBPMULTITHREAD" >&AS_MESSAGE_LOG_FD
-    fi
+    ])
     AC_MSG_CHECKING([whether POSIX threads API is available])
     AC_MSG_RESULT([$gl_pthread_api])
     AC_SUBST([LIBPTHREAD])
     AC_SUBST([LIBPMULTITHREAD])
-    if test $gl_pthread_api = yes; then
+    AS_IF([test $gl_pthread_api = yes], [
       AC_DEFINE([HAVE_PTHREAD_API], [1],
         [Define if you have the <pthread.h> header and the POSIX threads API.])
-    fi
+    ])
 
     dnl On some systems, sched_yield is in librt, rather than in libpthread.
     AC_LINK_IFELSE(
       [AC_LANG_PROGRAM(
-         [[#include <sched.h>]],
+         [[#include <sched.h>
+         ]],
          [[sched_yield ();]])],
-      [LIB_SCHED_YIELD=
+      [SCHED_YIELD_LIB=
       ],
       [dnl Solaris 7...10 has sched_yield in librt, not in libpthread or libc.
-       AC_CHECK_LIB([rt], [sched_yield], [LIB_SCHED_YIELD=-lrt],
+       AC_CHECK_LIB([rt], [sched_yield], [SCHED_YIELD_LIB=-lrt],
          [dnl Solaris 2.5.1, 2.6 has sched_yield in libposix4, not librt.
-          AC_CHECK_LIB([posix4], [sched_yield], [LIB_SCHED_YIELD=-lposix4])])
+          AC_CHECK_LIB([posix4], [sched_yield], [SCHED_YIELD_LIB=-lposix4])])
       ])
+    AC_SUBST([SCHED_YIELD_LIB])
+    dnl For backward compatibility.
+    LIB_SCHED_YIELD="$SCHED_YIELD_LIB"
     AC_SUBST([LIB_SCHED_YIELD])
 
     gl_pthreadlib_body_done=done
-  fi
+  ])
 ])
 
 AC_DEFUN([gl_PTHREADLIB],
@@ -336,44 +348,45 @@ AC_DEFUN([gl_STDTHREADLIB_BODY],
 [
   AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
   AC_REQUIRE([AC_CANONICAL_HOST])
-  if test -z "$gl_stdthreadlib_body_done"; then
+  AS_IF([test -z "$gl_stdthreadlib_body_done"], [
     AC_CHECK_HEADERS_ONCE([threads.h])
 
-    case "$host_os" in
-      mingw*)
+    AS_CASE([$host_os],
+      [mingw* | windows*],
+       [
         LIBSTDTHREAD=
-        ;;
-      *)
+       ],
+       [
         gl_PTHREADLIB_BODY
-        if test $ac_cv_header_threads_h = yes; then
+        AS_IF([test $ac_cv_header_threads_h = yes], [
           dnl glibc >= 2.29 has thrd_create in libpthread.
           dnl FreeBSD >= 10 has thrd_create in libstdthreads; this library depends
-          dnl on libpthread (for the symbol 'pthread_mutexattr_gettype').
+          dnl on libpthread (for the symbol pthread_mutexattr_gettype).
           dnl glibc >= 2.34, AIX >= 7.1, and Solaris >= 11.4 have thrd_create in
           dnl libc.
-          AC_CHECK_FUNCS([thrd_create])
-          if test $ac_cv_func_thrd_create = yes; then
+          gl_CHECK_FUNCS_ANDROID([thrd_create], [[#include <threads.h>
+                                                ]])
+          AS_IF([test $ac_cv_func_thrd_create = yes], [
             LIBSTDTHREAD=
-          else
+          ], [
             AC_CHECK_LIB([stdthreads], [thrd_create], [
-              LIBSTDTHREAD='-lstdthreads -lpthread'
+              LIBSTDTHREAD="-lstdthreads -lpthread"
             ], [
               dnl Guess that thrd_create is in libpthread.
               LIBSTDTHREAD="$LIBPMULTITHREAD"
             ])
-          fi
-        else
+          ])
+        ], [
           dnl Libraries needed by thrd.c, mtx.c, cnd.c, tss.c.
-          LIBSTDTHREAD="$LIBPMULTITHREAD $LIB_SCHED_YIELD"
-        fi
-        ;;
-    esac
+          LIBSTDTHREAD="$LIBPMULTITHREAD $SCHED_YIELD_LIB"
+        ])
+       ])
     AC_SUBST([LIBSTDTHREAD])
 
     AC_MSG_CHECKING([whether ISO C threads API is available])
     AC_MSG_RESULT([$ac_cv_header_threads_h])
     gl_stdthreadlib_body_done=done
-  fi
+  ])
 ])
 
 AC_DEFUN([gl_STDTHREADLIB],
@@ -390,7 +403,7 @@ dnl ------------
 dnl Tests for a multithreading library to be used.
 dnl If the configure.ac contains a definition of the gl_THREADLIB_DEFAULT_NO
 dnl (it must be placed before the invocation of gl_THREADLIB_EARLY!), then the
-dnl default is 'no', otherwise it is system dependent. In both cases, the user
+dnl default is "no", otherwise it is system dependent. In both cases, the user
 dnl can change the choice through the options --enable-threads=choice or
 dnl --disable-threads.
 dnl Defines at most one of the macros USE_ISOC_THREADS, USE_POSIX_THREADS,
@@ -435,49 +448,45 @@ AC_DEFUN([gl_THREADLIB_EARLY_BODY],
   m4_ifdef([gl_THREADLIB_DEFAULT_NO],
     [m4_divert_text([DEFAULTS], [gl_use_threads_default=no])],
     [m4_divert_text([DEFAULTS], [gl_use_threads_default=])])
-  m4_divert_text([DEFAULTS], [gl_use_winpthreads_default=])
+  dnl gl_use_winpthreads_default defaults to "no", because in mingw 10, like
+  dnl in mingw 5, the use of libwinpthread still makes test-pthread-tss crash.
+  m4_divert_text([DEFAULTS], [gl_use_winpthreads_default=no])
   AC_ARG_ENABLE([threads],
-AS_HELP_STRING([--enable-threads={isoc|posix|isoc+posix|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
-AS_HELP_STRING([--disable-threads], [build without multithread safety])]),
+AS_HELP_STRING([[--enable-threads={isoc|posix|isoc+posix|windows}]], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
+AS_HELP_STRING([[--disable-threads]], [build without multithread safety])]),
     [gl_use_threads=$enableval],
     [if test -n "$gl_use_threads_default"; then
        gl_use_threads="$gl_use_threads_default"
      else
-changequote(,)dnl
-       case "$host_os" in
+       AS_CASE([$host_os],
          dnl Disable multithreading by default on OSF/1, because it interferes
          dnl with fork()/exec(): When msgexec is linked with -lpthread, its
          dnl child process gets an endless segmentation fault inside execvp().
-         osf*) gl_use_threads=no ;;
+         [osf*], [gl_use_threads=no],
          dnl Disable multithreading by default on Cygwin 1.5.x, because it has
          dnl bugs that lead to endless loops or crashes. See
          dnl <https://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
-         cygwin*)
-               case `uname -r` in
-                 1.[0-5].*) gl_use_threads=no ;;
-                 *)         gl_use_threads=yes ;;
-               esac
-               ;;
+         [cygwin*],
+          [AS_CASE([$(uname -r)],
+             [[1.[0-5].*]], [gl_use_threads=no],
+                            [gl_use_threads=yes])
+          ],
          dnl Obey gl_AVOID_WINPTHREAD on mingw.
-         mingw*)
-               case "$gl_use_winpthreads_default" in
-                 yes) gl_use_threads=posix ;;
-                 no)  gl_use_threads=windows ;;
-                 *)   gl_use_threads=yes ;;
-               esac
-               ;;
-         *)    gl_use_threads=yes ;;
-       esac
-changequote([,])dnl
+         [mingw* | windows*],
+          [AS_CASE([$gl_use_winpthreads_default],
+             [yes], [gl_use_threads=posix],
+             [no],  [gl_use_threads=windows],
+                    [gl_use_threads=yes])
+          ],
+          [gl_use_threads=yes])
      fi
     ])
-  if test "$gl_use_threads" = yes \
-     || test "$gl_use_threads" = isoc \
-     || test "$gl_use_threads" = posix \
-     || test "$gl_use_threads" = isoc+posix; then
-    # For using <threads.h> or <pthread.h>:
-    gl_ANYTHREADLIB_EARLY
-  fi
+  AS_CASE([$gl_use_threads],
+    [yes | isoc | posix | isoc+posix],
+     [
+      # For using <threads.h> or <pthread.h>:
+      gl_ANYTHREADLIB_EARLY
+     ])
 ])
 
 dnl The guts of gl_THREADLIB. Needs to be expanded only once.
@@ -490,86 +499,95 @@ AC_DEFUN([gl_THREADLIB_BODY],
   LTLIBTHREAD=
   LIBMULTITHREAD=
   LTLIBMULTITHREAD=
-  if test "$gl_use_threads" != no; then
+  AS_IF([test "$gl_use_threads" = no],
+   [AC_DEFINE([AVOID_ANY_THREADS], [1],
+      [Define if no multithread safety and no multithreading is desired.])],
+   [
     dnl Check whether the compiler and linker support weak declarations.
     gl_WEAK_SYMBOLS
-    if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
-      dnl If we use weak symbols to implement pthread_in_use / pth_in_use /
-      dnl thread_in_use, we also need to test whether the ISO C 11 thrd_create
-      dnl facility is in use.
-      AC_CHECK_HEADERS_ONCE([threads.h])
-      :
-    fi
-    if test "$gl_use_threads" = isoc || test "$gl_use_threads" = isoc+posix; then
-      AC_CHECK_HEADERS_ONCE([threads.h])
-      gl_have_isoc_threads="$ac_cv_header_threads_h"
-    fi
-    if test "$gl_use_threads" = yes \
-       || test "$gl_use_threads" = posix \
-       || test "$gl_use_threads" = isoc+posix; then
-      gl_PTHREADLIB_BODY
-      LIBTHREAD=$LIBPTHREAD LTLIBTHREAD=$LIBPTHREAD
-      LIBMULTITHREAD=$LIBPMULTITHREAD LTLIBMULTITHREAD=$LIBPMULTITHREAD
-      if test $gl_pthread_api = yes; then
-        if test "$gl_use_threads" = isoc+posix && test "$gl_have_isoc_threads" = yes; then
-          gl_threads_api='isoc+posix'
-          AC_DEFINE([USE_ISOC_AND_POSIX_THREADS], [1],
-            [Define if the combination of the ISO C and POSIX multithreading APIs can be used.])
-          LIBTHREAD= LTLIBTHREAD=
-        else
-          gl_threads_api=posix
-          AC_DEFINE([USE_POSIX_THREADS], [1],
-            [Define if the POSIX multithreading library can be used.])
-          if test -z "$LIBMULTITHREAD" && test -z "$LTLIBMULTITHREAD"; then
-            AC_DEFINE([USE_POSIX_THREADS_FROM_LIBC], [1],
-              [Define if references to the POSIX multithreading library are satisfied by libc.])
-          else
-            if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
-              AC_DEFINE([USE_POSIX_THREADS_WEAK], [1],
-                [Define if references to the POSIX multithreading library should be made weak.])
-              LIBTHREAD= LTLIBTHREAD=
-            else
-              case "$host_os" in
-                freebsd* | dragonfly* | midnightbsd*)
-                  if test "x$LIBTHREAD" != "x$LIBMULTITHREAD"; then
-                    dnl If weak symbols can't tell whether pthread_create(), pthread_key_create()
-                    dnl etc. will succeed, we need a runtime test.
-                    AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
-                      [Define if the pthread_in_use() detection is hard.])
-                  fi
-                  ;;
-              esac
-            fi
-          fi
-        fi
-      fi
-    fi
-    if test $gl_threads_api = none; then
-      if test "$gl_use_threads" = isoc && test "$gl_have_isoc_threads" = yes; then
+    AS_CASE([$gl_cv_have_weak],
+      [*yes],
+       [
+        dnl If we use weak symbols to implement pthread_in_use / pth_in_use /
+        dnl thread_in_use, we also need to test whether the ISO C 11 thrd_create
+        dnl facility is in use.
+        AC_CHECK_HEADERS_ONCE([threads.h])
+        :
+       ])
+    AS_CASE([$gl_use_threads],
+      [isoc | isoc+posix],
+       [
+        AC_CHECK_HEADERS_ONCE([threads.h])
+        gl_have_isoc_threads="$ac_cv_header_threads_h"
+       ])
+    AS_CASE([$gl_use_threads],
+      [yes | posix | isoc+posix],
+       [
+        gl_PTHREADLIB_BODY
+        LIBTHREAD=$LIBPTHREAD LTLIBTHREAD=$LIBPTHREAD
+        LIBMULTITHREAD=$LIBPMULTITHREAD LTLIBMULTITHREAD=$LIBPMULTITHREAD
+        AS_IF([test $gl_pthread_api = yes], [
+          AS_IF([test "$gl_use_threads" = isoc+posix &&
+                 test "$gl_have_isoc_threads" = yes], [
+            gl_threads_api="isoc+posix"
+            AC_DEFINE([USE_ISOC_AND_POSIX_THREADS], [1],
+              [Define if the combination of the ISO C and POSIX multithreading APIs can be used.])
+            LIBTHREAD= LTLIBTHREAD=
+          ], [
+            gl_threads_api=posix
+            AC_DEFINE([USE_POSIX_THREADS], [1],
+              [Define if the POSIX multithreading library can be used.])
+            AS_IF([test -z "$LIBMULTITHREAD" && test -z "$LTLIBMULTITHREAD"], [
+              AC_DEFINE([USE_POSIX_THREADS_FROM_LIBC], [1],
+                [Define if references to the POSIX multithreading library are satisfied by libc.])
+            ], [
+              AS_CASE([$gl_cv_have_weak],
+                [*yes],
+                 [
+                  AC_DEFINE([USE_POSIX_THREADS_WEAK], [1],
+                    [Define if references to the POSIX multithreading library should be made weak.])
+                  LIBTHREAD= LTLIBTHREAD=
+                 ],
+                 [AS_CASE([$host_os],
+                    [freebsd* | dragonfly* | midnightbsd*],
+                     [
+                      AS_IF([test "x$LIBTHREAD" != "x$LIBMULTITHREAD"], [
+                        dnl If weak symbols cannot tell whether
+                        dnl pthread_create(), dnl pthread_key_create()
+                        dnl etc. will succeed, we need a runtime test.
+                        AC_DEFINE([PTHREAD_IN_USE_DETECTION_HARD], [1],
+                          [Define if the pthread_in_use() detection is hard.])
+                      ])
+                     ])
+                 ])
+            ])
+          ])
+        ])
+       ])
+    AS_IF([test $gl_threads_api = none], [
+      AS_IF([test "$gl_use_threads" = isoc && test "$gl_have_isoc_threads" = yes], [
         gl_STDTHREADLIB_BODY
         LIBTHREAD=$LIBSTDTHREAD LTLIBTHREAD=$LIBSTDTHREAD
         LIBMULTITHREAD=$LIBSTDTHREAD LTLIBMULTITHREAD=$LIBSTDTHREAD
         gl_threads_api=isoc
         AC_DEFINE([USE_ISOC_THREADS], [1],
           [Define if the ISO C multithreading library can be used.])
-      fi
-    fi
-    if test $gl_threads_api = none; then
-      case "$gl_use_threads" in
-        yes | windows | win32) # The 'win32' is for backward compatibility.
-          if { case "$host_os" in
-                 mingw*) true;;
-                 *) false;;
-               esac
-             }; then
-            gl_threads_api=windows
-            AC_DEFINE([USE_WINDOWS_THREADS], [1],
-              [Define if the native Windows multithreading API can be used.])
-          fi
-          ;;
-      esac
-    fi
-  fi
+      ])
+    ])
+    AS_IF([test $gl_threads_api = none], [
+      # The "win32" is for backward compatibility.
+      AS_CASE([$gl_use_threads],
+        [yes | windows | win32],
+         [AS_CASE([$host_os],
+            [mingw* | windows*],
+             [
+              gl_threads_api=windows
+              AC_DEFINE([USE_WINDOWS_THREADS], [1],
+                [Define if the native Windows multithreading API can be used.])
+             ])
+         ])
+    ])
+   ])
   AC_MSG_CHECKING([for multithread API to use])
   AC_MSG_RESULT([$gl_threads_api])
   AC_SUBST([LIBTHREAD])
@@ -589,7 +607,7 @@ dnl gl_DISABLE_THREADS
 dnl ------------------
 dnl Sets the gl_THREADLIB default so that threads are not used by default.
 dnl The user can still override it at installation time, by using the
-dnl configure option '--enable-threads'.
+dnl configure option "--enable-threads".
 
 AC_DEFUN([gl_DISABLE_THREADS], [
   m4_divert_text([INIT_PREPARE], [gl_use_threads_default=no])
@@ -601,7 +619,8 @@ dnl -------------------
 dnl Sets the gl_THREADLIB default so that on mingw, a dependency to the
 dnl libwinpthread DLL (mingw-w64 winpthreads library) is avoided.
 dnl The user can still override it at installation time, by using the
-dnl configure option '--enable-threads'.
+dnl configure option "--enable-threads=posix".
+dnl As of 2023, this is now the default.
 
 AC_DEFUN([gl_AVOID_WINPTHREAD], [
   m4_divert_text([INIT_PREPARE], [gl_use_winpthreads_default=no])
diff --git a/gl/m4/time_h.m4 b/gl/m4/time_h.m4
index f6bf3a4f..f4d8e20f 100644
--- a/gl/m4/time_h.m4
+++ b/gl/m4/time_h.m4
@@ -1,12 +1,13 @@
-# Configure a more-standard replacement for <time.h>.
-
-# Copyright (C) 2000-2001, 2003-2007, 2009-2023 Free Software Foundation, Inc.
-
-# serial 20
+# time_h.m4
+# serial 27
+dnl Copyright (C) 2000-2001, 2003-2007, 2009-2025 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# Configure a more-standard replacement for <time.h>.
 
 # Written by Paul Eggert and Jim Meyering.
 
@@ -23,7 +24,10 @@ AC_DEFUN_ONCE([gl_TIME_H],
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[
 #include <time.h>
-    ]], [asctime_r ctime_r])
+    ]], [
+      asctime asctime_r ctime ctime_r gmtime_r localtime localtime_r mktime
+      nanosleep strftime strptime time timegm timespec_get timespec_getres tzset
+    ])
 
   AC_REQUIRE([AC_C_RESTRICT])
 
@@ -137,11 +141,13 @@ AC_DEFUN([gl_TIME_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_NANOSLEEP])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRFTIME])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_STRPTIME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIME])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIMEGM])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIMESPEC_GET])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIMESPEC_GETRES])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIME_R])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TIME_RZ])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TZNAME])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_TZSET])
     dnl Support Microsoft deprecated alias function names by default.
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_TZSET], [1])
@@ -159,25 +165,21 @@ AC_DEFUN([gl_TIME_H_DEFAULTS],
   HAVE_TIMEGM=1;                         AC_SUBST([HAVE_TIMEGM])
   HAVE_TIMESPEC_GET=1;                   AC_SUBST([HAVE_TIMESPEC_GET])
   HAVE_TIMESPEC_GETRES=1;                AC_SUBST([HAVE_TIMESPEC_GETRES])
-  dnl Even GNU libc does not have timezone_t yet.
+  dnl Even GNU libc does not have timezone_t and tzalloc() yet.
   HAVE_TIMEZONE_T=0;                     AC_SUBST([HAVE_TIMEZONE_T])
-  dnl If another module says to replace or to not replace, do that.
-  dnl Otherwise, replace only if someone compiles with -DGNULIB_PORTCHECK;
-  dnl this lets maintainers check for portability.
-  REPLACE_CTIME=GNULIB_PORTCHECK;        AC_SUBST([REPLACE_CTIME])
-  REPLACE_LOCALTIME_R=GNULIB_PORTCHECK;  AC_SUBST([REPLACE_LOCALTIME_R])
-  REPLACE_MKTIME=GNULIB_PORTCHECK;       AC_SUBST([REPLACE_MKTIME])
-  REPLACE_NANOSLEEP=GNULIB_PORTCHECK;    AC_SUBST([REPLACE_NANOSLEEP])
-  REPLACE_STRFTIME=GNULIB_PORTCHECK;     AC_SUBST([REPLACE_STRFTIME])
-  REPLACE_TIMEGM=GNULIB_PORTCHECK;       AC_SUBST([REPLACE_TIMEGM])
-  REPLACE_TZSET=GNULIB_PORTCHECK;        AC_SUBST([REPLACE_TZSET])
-
-  dnl Hack so that the time module doesn't depend on the sys_time module.
-  dnl First, default GNULIB_GETTIMEOFDAY to 0 if sys_time is absent.
-  : ${GNULIB_GETTIMEOFDAY=0};            AC_SUBST([GNULIB_GETTIMEOFDAY])
-  dnl Second, it's OK to not use GNULIB_PORTCHECK for REPLACE_GMTIME
-  dnl and REPLACE_LOCALTIME, as portability to Solaris 2.6 and earlier
-  dnl is no longer a big deal.
+  HAVE_TZALLOC=0;                        AC_SUBST([HAVE_TZALLOC])
+  REPLACE_CTIME=0;                       AC_SUBST([REPLACE_CTIME])
   REPLACE_GMTIME=0;                      AC_SUBST([REPLACE_GMTIME])
   REPLACE_LOCALTIME=0;                   AC_SUBST([REPLACE_LOCALTIME])
+  REPLACE_LOCALTIME_R=0;                 AC_SUBST([REPLACE_LOCALTIME_R])
+  REPLACE_LOCALTIME_RZ=0;                AC_SUBST([REPLACE_LOCALTIME_RZ])
+  REPLACE_MKTIME=0;                      AC_SUBST([REPLACE_MKTIME])
+  REPLACE_MKTIME_Z=0;                    AC_SUBST([REPLACE_MKTIME_Z])
+  REPLACE_NANOSLEEP=0;                   AC_SUBST([REPLACE_NANOSLEEP])
+  REPLACE_STRFTIME=0;                    AC_SUBST([REPLACE_STRFTIME])
+  REPLACE_TIME=0;                        AC_SUBST([REPLACE_TIME])
+  REPLACE_TIMEGM=0;                      AC_SUBST([REPLACE_TIMEGM])
+  REPLACE_TIMESPEC_GET=0;                AC_SUBST([REPLACE_TIMESPEC_GET])
+  REPLACE_TIMESPEC_GETRES=0;             AC_SUBST([REPLACE_TIMESPEC_GETRES])
+  REPLACE_TZSET=0;                       AC_SUBST([REPLACE_TZSET])
 ])
diff --git a/gl/m4/time_r.m4 b/gl/m4/time_r.m4
index adce438a..96f5c5b5 100644
--- a/gl/m4/time_r.m4
+++ b/gl/m4/time_r.m4
@@ -1,9 +1,12 @@
-dnl Reentrant time functions: localtime_r, gmtime_r.
-
-dnl Copyright (C) 2003, 2006-2023 Free Software Foundation, Inc.
+# time_r.m4
+# serial 1
+dnl Copyright (C) 2003, 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl Reentrant time functions: localtime_r, gmtime_r.
 
 dnl Written by Paul Eggert.
 
@@ -57,9 +60,7 @@ AC_DEFUN([gl_TIME_R],
          [gl_cv_time_r_posix=yes],
          [gl_cv_time_r_posix=no])
       ])
-    if test $gl_cv_time_r_posix = yes; then
-      REPLACE_LOCALTIME_R=0
-    else
+    if test $gl_cv_time_r_posix != yes; then
       REPLACE_LOCALTIME_R=1
     fi
   else
diff --git a/gl/m4/timegm.m4 b/gl/m4/timegm.m4
index 6079f1a3..cb6da6da 100644
--- a/gl/m4/timegm.m4
+++ b/gl/m4/timegm.m4
@@ -1,15 +1,16 @@
-# timegm.m4 serial 13
-dnl Copyright (C) 2003, 2007, 2009-2023 Free Software Foundation, Inc.
+# timegm.m4
+# serial 16
+dnl Copyright (C) 2003, 2007, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_TIMEGM],
 [
   AC_REQUIRE([gl_TIME_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_MKTIME_WORKS])
-  REPLACE_TIMEGM=0
-  AC_CHECK_FUNCS_ONCE([timegm])
+  gl_CHECK_FUNCS_ANDROID([timegm], [[#include <time.h>]])
   if test $ac_cv_func_timegm = yes; then
     if test "$gl_cv_func_working_mktime" != yes; then
       # Assume that timegm is buggy if mktime is.
@@ -17,6 +18,9 @@ AC_DEFUN([gl_FUNC_TIMEGM],
     fi
   else
     HAVE_TIMEGM=0
+    case "$gl_cv_onwards_func_timegm" in
+      future*) REPLACE_TIMEGM=1 ;;
+    esac
   fi
 ])
 
diff --git a/gl/m4/uchar_h.m4 b/gl/m4/uchar_h.m4
new file mode 100644
index 00000000..b2309385
--- /dev/null
+++ b/gl/m4/uchar_h.m4
@@ -0,0 +1,279 @@
+# uchar_h.m4
+# serial 32
+dnl Copyright (C) 2019-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl From Bruno Haible.
+dnl Prepare the overridden <uchar.h>.
+
+AC_DEFUN_ONCE([gl_UCHAR_H],
+[
+  AC_REQUIRE([gl_UCHAR_H_DEFAULTS])
+
+  gl_CHECK_NEXT_HEADERS([uchar.h])
+  if test $ac_cv_header_uchar_h = yes; then
+    HAVE_UCHAR_H=1
+  else
+    HAVE_UCHAR_H=0
+  fi
+  AC_SUBST([HAVE_UCHAR_H])
+
+  dnl On macOS 15, in C mode, <uchar.h> does not exist. But in C++ mode,
+  dnl it exists, and we need to #include_next it, otherwise we get an error
+  dnl "<cuchar> tried including <uchar.h> but didn't find libc++'s <uchar.h>
+  dnl  header."
+  m4_ifdef([gl_ANSI_CXX], [AC_REQUIRE([gl_ANSI_CXX])])
+  CXX_HAVE_UCHAR_H=0
+  if test "$CXX" != no; then
+    AC_CACHE_CHECK([whether the C++ compiler has <uchar.h>],
+      [gl_cv_cxx_have_uchar_h],
+      [dnl We can't use AC_LANG_PUSH([C++]) and AC_LANG_POP([C++]) here, due to
+       dnl an autoconf bug <https://savannah.gnu.org/support/?110294>.
+       cat > conftest.cpp <<\EOF
+#include <uchar.h>
+EOF
+       gl_command="$CXX $CXXFLAGS $CPPFLAGS -c conftest.cpp"
+       if AC_TRY_EVAL([gl_command]); then
+         gl_cv_cxx_have_uchar_h=yes
+       else
+         gl_cv_cxx_have_uchar_h=no
+       fi
+       rm -fr conftest*
+      ])
+    if test $gl_cv_cxx_have_uchar_h = yes; then
+      CXX_HAVE_UCHAR_H=1
+    fi
+  fi
+  AC_SUBST([CXX_HAVE_UCHAR_H])
+
+  gl_TYPE_CHAR8_T
+  gl_TYPE_CHAR16_T
+  gl_TYPE_CHAR32_T
+
+  dnl In C++ mode, clang defines 'char16_t' and 'char32_t' as built-in types
+  dnl on some platforms (e.g. OpenBSD 6.7), and as types defined by many
+  dnl header files (<limits.h>, <stddef.h>, <stdint.h>, <stdio.h>, <stdlib.h>
+  dnl and others) on some platforms (e.g. Mac OS X 10.13).
+  dnl The same thing may also happen for 'char8_t'; so, be prepared for it.
+  m4_ifdef([gl_ANSI_CXX], [AC_REQUIRE([gl_ANSI_CXX])])
+  CXX_HAS_UCHAR_TYPES=0
+  if test $HAVE_UCHAR_H = 0; then
+    if test "$CXX" != no; then
+      AC_CACHE_CHECK([whether the C++ compiler predefines the <uchar.h> types],
+        [gl_cv_cxx_has_uchar_types],
+        [dnl We can't use AC_LANG_PUSH([C++]) and AC_LANG_POP([C++]) here, due to
+         dnl an autoconf bug <https://savannah.gnu.org/support/?110294>.
+         cat > conftest.cpp <<\EOF
+#include <stddef.h>
+char16_t a;
+char32_t b;
+EOF
+         gl_command="$CXX $CXXFLAGS $CPPFLAGS -c conftest.cpp"
+         if AC_TRY_EVAL([gl_command]); then
+           gl_cv_cxx_has_uchar_types=yes
+         else
+           gl_cv_cxx_has_uchar_types=no
+         fi
+         rm -fr conftest*
+        ])
+      if test $gl_cv_cxx_has_uchar_types = yes; then
+        CXX_HAS_UCHAR_TYPES=1
+      fi
+    fi
+  fi
+  AC_SUBST([CXX_HAS_UCHAR_TYPES])
+  CXX_HAS_CHAR8_TYPE=0
+  if test $HAVE_UCHAR_H = 0; then
+    if test "$CXX" != no; then
+      AC_CACHE_CHECK([whether the C++ compiler predefines the char8_t type],
+        [gl_cv_cxx_has_char8_type],
+        [dnl We can't use AC_LANG_PUSH([C++]) and AC_LANG_POP([C++]) here, due to
+         dnl an autoconf bug <https://savannah.gnu.org/support/?110294>.
+         cat > conftest.cpp <<\EOF
+#include <stddef.h>
+char8_t a;
+EOF
+         gl_command="$CXX $CXXFLAGS $CPPFLAGS -c conftest.cpp"
+         if AC_TRY_EVAL([gl_command]); then
+           gl_cv_cxx_has_char8_type=yes
+         else
+           gl_cv_cxx_has_char8_type=no
+         fi
+         rm -fr conftest*
+        ])
+      if test $gl_cv_cxx_has_char8_type = yes; then
+        CXX_HAS_CHAR8_TYPE=1
+      fi
+    fi
+  fi
+  AC_SUBST([CXX_HAS_CHAR8_TYPE])
+
+  dnl Test whether a 'char32_t' can hold more characters than a 'wchar_t'.
+  gl_STDINT_BITSIZEOF([wchar_t], [gl_STDINT_INCLUDES])
+  if test $BITSIZEOF_WCHAR_T -lt 32; then
+    SMALL_WCHAR_T=1
+  else
+    SMALL_WCHAR_T=0
+  fi
+  dnl SMALL_WCHAR_T is expected to be 1 on 32-bit AIX, Cygwin, native Windows.
+  AC_SUBST([SMALL_WCHAR_T])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use, and which is not
+  dnl guaranteed by C11.
+  gl_WARN_ON_USE_PREPARE([[
+      #ifdef __HAIKU__
+       #include <stdint.h>
+      #endif
+      #include <uchar.h>
+    ]], [c32rtomb mbrtoc16 mbrtoc32])
+])
+
+AC_DEFUN_ONCE([gl_TYPE_CHAR8_T],
+[
+  dnl Determine whether gnulib's <uchar.h> would, if present, override char8_t.
+  AC_CACHE_CHECK([whether char8_t is correctly defined],
+    [gl_cv_type_char8_t_works],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[
+          #ifdef __HAIKU__
+           #include <stdint.h>
+          #endif
+          #include <uchar.h>
+          int verify[(char8_t)(-1) >= 0 && sizeof (char8_t) == sizeof (unsigned char) ? 1 : -1];
+          ]])
+       ],
+       [gl_cv_type_char8_t_works=yes],
+       [gl_cv_type_char8_t_works=no])
+    ])
+  if test $gl_cv_type_char8_t_works = no; then
+    GNULIBHEADERS_OVERRIDE_CHAR8_T=1
+  else
+    GNULIBHEADERS_OVERRIDE_CHAR8_T=0
+  fi
+  AC_SUBST([GNULIBHEADERS_OVERRIDE_CHAR8_T])
+])
+
+dnl On Haiku 2020, char16_t and char32_t are incorrectly defined.
+dnl See <https://dev.haiku-os.org/ticket/15990>.
+AC_DEFUN_ONCE([gl_TYPE_CHAR16_T],
+[
+  dnl Determine whether gnulib's <uchar.h> would, if present, override char16_t.
+  AC_CACHE_CHECK([whether char16_t is correctly defined],
+    [gl_cv_type_char16_t_works],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[
+          #ifdef __HAIKU__
+           #include <stdint.h>
+          #endif
+          #include <uchar.h>
+          /* For simplicity, assume that uint16_least_t is equivalent to
+             'unsigned short'.  */
+          int verify[(char16_t)(-1) >= 0 && sizeof (char16_t) == sizeof (unsigned short) ? 1 : -1];
+          ]])
+       ],
+       [gl_cv_type_char16_t_works=yes],
+       [gl_cv_type_char16_t_works=no])
+    ])
+  if test $gl_cv_type_char16_t_works = no; then
+    GNULIBHEADERS_OVERRIDE_CHAR16_T=1
+  else
+    GNULIBHEADERS_OVERRIDE_CHAR16_T=0
+  fi
+  AC_SUBST([GNULIBHEADERS_OVERRIDE_CHAR16_T])
+])
+AC_DEFUN_ONCE([gl_TYPE_CHAR32_T],
+[
+  dnl Determine whether gnulib's <uchar.h> would, if present, override char32_t.
+  AC_CACHE_CHECK([whether char32_t is correctly defined],
+    [gl_cv_type_char32_t_works],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[
+          #ifdef __HAIKU__
+           #include <stdint.h>
+          #endif
+          #include <uchar.h>
+          /* For simplicity, assume that uint32_least_t is equivalent to
+             'unsigned int'.  */
+          int verify[(char32_t)(-1) >= 0 && sizeof (char32_t) == sizeof (unsigned int) ? 1 : -1];
+          ]])
+       ],
+       [gl_cv_type_char32_t_works=yes],
+       [gl_cv_type_char32_t_works=no])
+    ])
+  if test $gl_cv_type_char32_t_works = no; then
+    GNULIBHEADERS_OVERRIDE_CHAR32_T=1
+  else
+    GNULIBHEADERS_OVERRIDE_CHAR32_T=0
+  fi
+  AC_SUBST([GNULIBHEADERS_OVERRIDE_CHAR32_T])
+])
+
+# gl_UCHAR_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
+AC_DEFUN([gl_UCHAR_MODULE_INDICATOR],
+[
+  dnl Ensure to expand the default settings once only.
+  gl_UCHAR_H_REQUIRE_DEFAULTS
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_UCHAR_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_UCHAR_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_BTOC32])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISALNUM])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISALPHA])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISBLANK])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISCNTRL])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISDIGIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISGRAPH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISLOWER])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISPRINT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISPUNCT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISSPACE])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISUPPER])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32ISXDIGIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32TOLOWER])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32TOUPPER])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32WIDTH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32RTOMB])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32SNRTOMBS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32SRTOMBS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32STOMBS])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32SWIDTH])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32TOB])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32_APPLY_MAPPING])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32_APPLY_TYPE_TEST])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32_GET_MAPPING])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_C32_GET_TYPE_TEST])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBRTOC16])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBRTOC32])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSNRTOC32S])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSRTOC32S])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSTOC32S])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_UCHAR_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_UCHAR_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_UCHAR_H_DEFAULTS],
+[
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_C32RTOMB=1;             AC_SUBST([HAVE_C32RTOMB])
+  HAVE_MBRTOC16=1;             AC_SUBST([HAVE_MBRTOC16])
+  HAVE_MBRTOC32=1;             AC_SUBST([HAVE_MBRTOC32])
+  REPLACE_C32RTOMB=0;          AC_SUBST([REPLACE_C32RTOMB])
+  REPLACE_MBRTOC16=0;          AC_SUBST([REPLACE_MBRTOC16])
+  REPLACE_MBRTOC32=0;          AC_SUBST([REPLACE_MBRTOC32])
+])
diff --git a/gl/m4/ungetc.m4 b/gl/m4/ungetc.m4
index 8977a346..969b60e8 100644
--- a/gl/m4/ungetc.m4
+++ b/gl/m4/ungetc.m4
@@ -1,8 +1,10 @@
-# ungetc.m4 serial 10
-dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+# ungetc.m4
+# serial 12
+dnl Copyright (C) 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN_ONCE([gl_FUNC_UNGETC_WORKS],
 [
@@ -42,16 +44,16 @@ AC_DEFUN_ONCE([gl_FUNC_UNGETC_WORKS],
           ]])],
         [gl_cv_func_ungetc_works=yes], [gl_cv_func_ungetc_works=no],
         [case "$host_os" in
-                          # Guess yes on glibc systems.
-           *-gnu* | gnu*) gl_cv_func_ungetc_works="guessing yes" ;;
-                          # Guess yes on musl systems.
-           *-musl*)       gl_cv_func_ungetc_works="guessing yes" ;;
-                          # Guess yes on bionic systems.
-           *-android*)    gl_cv_func_ungetc_works="guessing yes" ;;
-                          # Guess yes on native Windows.
-           mingw*)        gl_cv_func_ungetc_works="guessing yes" ;;
-                          # If we don't know, obey --enable-cross-guesses.
-           *)             gl_cv_func_ungetc_works="$gl_cross_guess_normal" ;;
+                               # Guess yes on glibc systems.
+           *-gnu* | gnu*)      gl_cv_func_ungetc_works="guessing yes" ;;
+                               # Guess yes on musl systems.
+           *-musl* | midipix*) gl_cv_func_ungetc_works="guessing yes" ;;
+                               # Guess yes on bionic systems.
+           *-android*)         gl_cv_func_ungetc_works="guessing yes" ;;
+                               # Guess yes on native Windows.
+           mingw* | windows*)  gl_cv_func_ungetc_works="guessing yes" ;;
+                               # If we don't know, obey --enable-cross-guesses.
+           *)                  gl_cv_func_ungetc_works="$gl_cross_guess_normal" ;;
          esac
         ])
     ])
diff --git a/gl/m4/unicase_h.m4 b/gl/m4/unicase_h.m4
new file mode 100644
index 00000000..bf5d4c2e
--- /dev/null
+++ b/gl/m4/unicase_h.m4
@@ -0,0 +1,45 @@
+# unicase_h.m4
+# serial 1
+dnl Copyright (C) 2023-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_UNICASE_H],
+[
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
+  AC_REQUIRE([gl_UNICASE_H_DEFAULTS])
+])
+
+# gl_UNICASE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
+AC_DEFUN([gl_UNICASE_MODULE_INDICATOR],
+[
+  dnl Ensure to expand the default settings once only.
+  gl_UNICASE_H_REQUIRE_DEFAULTS
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_UNICASE_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_UNICASE_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICASE_EMPTY_PREFIX_CONTEXT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICASE_EMPTY_SUFFIX_CONTEXT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_UNICASE_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_UNICASE_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_UNICASE_H_DEFAULTS],
+[
+  dnl Assume proper GNU behavior unless another module says otherwise.
+])
diff --git a/gl/m4/unictype_h.m4 b/gl/m4/unictype_h.m4
new file mode 100644
index 00000000..68ddaf6c
--- /dev/null
+++ b/gl/m4/unictype_h.m4
@@ -0,0 +1,179 @@
+# unictype_h.m4
+# serial 4
+dnl Copyright (C) 2023-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_UNICTYPE_H],
+[
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
+  AC_REQUIRE([gl_UNICTYPE_H_DEFAULTS])
+])
+
+# gl_UNICTYPE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
+AC_DEFUN([gl_UNICTYPE_MODULE_INDICATOR],
+[
+  dnl Ensure to expand the default settings once only.
+  gl_UNICTYPE_H_REQUIRE_DEFAULTS
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_UNICTYPE_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_UNICTYPE_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_L_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_LC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_LU_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_LL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_LT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_LM_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_LO_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_M_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_MN_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_MC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_ME_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_N_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_ND_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_NL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_NO_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_P_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_PC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_PD_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_PS_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_PE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_PI_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_PF_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_PO_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_S_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_SM_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_SC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_SK_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_SO_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_Z_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_ZS_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_ZL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_ZP_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_C_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_CC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_CF_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_CS_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_CO_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_CATEGORY_CN_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_WHITE_SPACE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_ALPHABETIC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_OTHER_ALPHABETIC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_NOT_A_CHARACTER_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_DEFAULT_IGNORABLE_CODE_POINT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_OTHER_DEFAULT_IGNORABLE_CODE_POINT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_DEPRECATED_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_LOGICAL_ORDER_EXCEPTION_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_VARIATION_SELECTOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_PRIVATE_USE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_UNASSIGNED_CODE_VALUE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_UPPERCASE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_OTHER_UPPERCASE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_LOWERCASE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_OTHER_LOWERCASE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_TITLECASE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_CASED_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_CASE_IGNORABLE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_CHANGES_WHEN_LOWERCASED_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_CHANGES_WHEN_UPPERCASED_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_CHANGES_WHEN_TITLECASED_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_CHANGES_WHEN_CASEFOLDED_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_CHANGES_WHEN_CASEMAPPED_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_SOFT_DOTTED_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_ID_START_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_OTHER_ID_START_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_ID_CONTINUE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_OTHER_ID_CONTINUE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_XID_START_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_XID_CONTINUE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_ID_COMPAT_MATH_START_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_ID_COMPAT_MATH_CONTINUE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_PATTERN_WHITE_SPACE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_PATTERN_SYNTAX_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_JOIN_CONTROL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_GRAPHEME_BASE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_GRAPHEME_EXTEND_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_OTHER_GRAPHEME_EXTEND_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_GRAPHEME_LINK_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_MODIFIER_COMBINING_MARK_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_CONTROL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_LEFT_TO_RIGHT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_HEBREW_RIGHT_TO_LEFT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_ARABIC_RIGHT_TO_LEFT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_EUROPEAN_DIGIT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_EUR_NUM_SEPARATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_EUR_NUM_TERMINATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_ARABIC_DIGIT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_COMMON_SEPARATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_BLOCK_SEPARATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_SEGMENT_SEPARATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_WHITESPACE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_NON_SPACING_MARK_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_BOUNDARY_NEUTRAL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_PDF_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_EMBEDDING_OR_OVERRIDE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_BIDI_OTHER_NEUTRAL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_HEX_DIGIT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_ASCII_HEX_DIGIT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_IDEOGRAPHIC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_UNIFIED_IDEOGRAPH_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_RADICAL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_IDS_UNARY_OPERATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_IDS_BINARY_OPERATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_IDS_TRINARY_OPERATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_EMOJI_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_EMOJI_PRESENTATION_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_EMOJI_MODIFIER_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_EMOJI_MODIFIER_BASE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_EMOJI_COMPONENT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_EXTENDED_PICTOGRAPHIC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_ZERO_WIDTH_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_SPACE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_NON_BREAK_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_ISO_CONTROL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_FORMAT_CONTROL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_PREPENDED_CONCATENATION_MARK_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_DASH_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_HYPHEN_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_PUNCTUATION_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_LINE_SEPARATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_PARAGRAPH_SEPARATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_QUOTATION_MARK_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_SENTENCE_TERMINAL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_TERMINAL_PUNCTUATION_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_CURRENCY_SYMBOL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_MATH_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_OTHER_MATH_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_PAIRED_PUNCTUATION_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_LEFT_OF_PAIR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_COMBINING_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_COMPOSITE_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_DECIMAL_DIGIT_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_NUMERIC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_DIACRITIC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_EXTENDER_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_IGNORABLE_CONTROL_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNICTYPE_PROPERTY_REGIONAL_INDICATOR_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_UNICTYPE_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_UNICTYPE_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_UNICTYPE_H_DEFAULTS],
+[
+  dnl Assume proper GNU behavior unless another module says otherwise.
+])
diff --git a/gl/m4/uninorm_h.m4 b/gl/m4/uninorm_h.m4
new file mode 100644
index 00000000..d416f73b
--- /dev/null
+++ b/gl/m4/uninorm_h.m4
@@ -0,0 +1,47 @@
+# uninorm_h.m4
+# serial 1
+dnl Copyright (C) 2023-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_UNINORM_H],
+[
+  dnl Ensure to expand the default settings once only, before all statements
+  dnl that occur in other macros.
+  AC_REQUIRE([gl_UNINORM_H_DEFAULTS])
+])
+
+# gl_UNINORM_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
+AC_DEFUN([gl_UNINORM_MODULE_INDICATOR],
+[
+  dnl Ensure to expand the default settings once only.
+  gl_UNINORM_H_REQUIRE_DEFAULTS
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
+AC_DEFUN([gl_UNINORM_H_REQUIRE_DEFAULTS],
+[
+  m4_defun(GL_MODULE_INDICATOR_PREFIX[_UNINORM_H_MODULE_INDICATOR_DEFAULTS], [
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNINORM_NFD_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNINORM_NFC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNINORM_NFKD_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_UNINORM_NFKC_DLL_VARIABLE], ['LIBUNISTRING_DLL_VARIABLE'])
+  ])
+  m4_require(GL_MODULE_INDICATOR_PREFIX[_UNINORM_H_MODULE_INDICATOR_DEFAULTS])
+  AC_REQUIRE([gl_UNINORM_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_UNINORM_H_DEFAULTS],
+[
+  dnl Assume proper GNU behavior unless another module says otherwise.
+])
diff --git a/gl/m4/unistd_h.m4 b/gl/m4/unistd_h.m4
index f4384027..6ec16286 100644
--- a/gl/m4/unistd_h.m4
+++ b/gl/m4/unistd_h.m4
@@ -1,8 +1,10 @@
-# unistd_h.m4 serial 90
-dnl Copyright (C) 2006-2023 Free Software Foundation, Inc.
+# unistd_h.m4
+# serial 97
+dnl Copyright (C) 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Written by Simon Josefsson, Bruno Haible.
 
@@ -225,6 +227,7 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   REPLACE_COPY_FILE_RANGE=0;         AC_SUBST([REPLACE_COPY_FILE_RANGE])
   REPLACE_DUP=0;                     AC_SUBST([REPLACE_DUP])
   REPLACE_DUP2=0;                    AC_SUBST([REPLACE_DUP2])
+  REPLACE_DUP3=0;                    AC_SUBST([REPLACE_DUP3])
   REPLACE_EXECL=0;                   AC_SUBST([REPLACE_EXECL])
   REPLACE_EXECLE=0;                  AC_SUBST([REPLACE_EXECLE])
   REPLACE_EXECLP=0;                  AC_SUBST([REPLACE_EXECLP])
@@ -233,27 +236,34 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   REPLACE_EXECVP=0;                  AC_SUBST([REPLACE_EXECVP])
   REPLACE_EXECVPE=0;                 AC_SUBST([REPLACE_EXECVPE])
   REPLACE_FACCESSAT=0;               AC_SUBST([REPLACE_FACCESSAT])
+  REPLACE_FCHDIR=0;                  AC_SUBST([REPLACE_FCHDIR])
   REPLACE_FCHOWNAT=0;                AC_SUBST([REPLACE_FCHOWNAT])
+  REPLACE_FDATASYNC=0;               AC_SUBST([REPLACE_FDATASYNC])
   REPLACE_FTRUNCATE=0;               AC_SUBST([REPLACE_FTRUNCATE])
   REPLACE_GETCWD=0;                  AC_SUBST([REPLACE_GETCWD])
   REPLACE_GETDOMAINNAME=0;           AC_SUBST([REPLACE_GETDOMAINNAME])
   REPLACE_GETDTABLESIZE=0;           AC_SUBST([REPLACE_GETDTABLESIZE])
+  REPLACE_GETENTROPY=0;              AC_SUBST([REPLACE_GETENTROPY])
+  REPLACE_GETLOGIN=0;                AC_SUBST([REPLACE_GETLOGIN])
   REPLACE_GETLOGIN_R=0;              AC_SUBST([REPLACE_GETLOGIN_R])
   REPLACE_GETGROUPS=0;               AC_SUBST([REPLACE_GETGROUPS])
   REPLACE_GETPAGESIZE=0;             AC_SUBST([REPLACE_GETPAGESIZE])
   REPLACE_GETPASS=0;                 AC_SUBST([REPLACE_GETPASS])
   REPLACE_GETPASS_FOR_GETPASS_GNU=0; AC_SUBST([REPLACE_GETPASS_FOR_GETPASS_GNU])
+  REPLACE_GETUSERSHELL=0;            AC_SUBST([REPLACE_GETUSERSHELL])
   REPLACE_ISATTY=0;                  AC_SUBST([REPLACE_ISATTY])
   REPLACE_LCHOWN=0;                  AC_SUBST([REPLACE_LCHOWN])
   REPLACE_LINK=0;                    AC_SUBST([REPLACE_LINK])
   REPLACE_LINKAT=0;                  AC_SUBST([REPLACE_LINKAT])
   REPLACE_LSEEK=0;                   AC_SUBST([REPLACE_LSEEK])
+  REPLACE_PIPE2=0;                   AC_SUBST([REPLACE_PIPE2])
   REPLACE_PREAD=0;                   AC_SUBST([REPLACE_PREAD])
   REPLACE_PWRITE=0;                  AC_SUBST([REPLACE_PWRITE])
   REPLACE_READ=0;                    AC_SUBST([REPLACE_READ])
   REPLACE_READLINK=0;                AC_SUBST([REPLACE_READLINK])
   REPLACE_READLINKAT=0;              AC_SUBST([REPLACE_READLINKAT])
   REPLACE_RMDIR=0;                   AC_SUBST([REPLACE_RMDIR])
+  REPLACE_SETHOSTNAME=0;             AC_SUBST([REPLACE_SETHOSTNAME])
   REPLACE_SLEEP=0;                   AC_SUBST([REPLACE_SLEEP])
   REPLACE_SYMLINK=0;                 AC_SUBST([REPLACE_SYMLINK])
   REPLACE_SYMLINKAT=0;               AC_SUBST([REPLACE_SYMLINKAT])
diff --git a/gl/m4/unitypes_h.m4 b/gl/m4/unitypes_h.m4
new file mode 100644
index 00000000..264e61be
--- /dev/null
+++ b/gl/m4/unitypes_h.m4
@@ -0,0 +1,26 @@
+# unitypes_h.m4
+# serial 1
+dnl Copyright (C) 2021-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_UNITYPES_H],
+[
+  AH_VERBATIM([unitypes_restrict], [
+/* This definition is a duplicate of the one in unitypes.h.
+   It is here so that we can cope with an older version of unitypes.h
+   that does not contain this definition and that is pre-installed among
+   the public header files.  */
+# if defined __restrict \
+     || 2 < __GNUC__ + (95 <= __GNUC_MINOR__) \
+     || __clang_major__ >= 3
+#  define _UC_RESTRICT __restrict
+# elif 199901L <= __STDC_VERSION__ || defined restrict
+#  define _UC_RESTRICT restrict
+# else
+#  define _UC_RESTRICT
+# endif
+])
+])
diff --git a/gl/m4/unlocked-io.m4 b/gl/m4/unlocked-io.m4
index 407c0bac..97f43f4b 100644
--- a/gl/m4/unlocked-io.m4
+++ b/gl/m4/unlocked-io.m4
@@ -1,10 +1,10 @@
-# unlocked-io.m4 serial 16
-
-# Copyright (C) 1998-2006, 2009-2023 Free Software Foundation, Inc.
-#
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# unlocked-io.m4
+# serial 16
+dnl Copyright (C) 1998-2006, 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Jim Meyering.
 dnl
diff --git a/gl/m4/vararrays.m4 b/gl/m4/vararrays.m4
index fd6230c2..086e409f 100644
--- a/gl/m4/vararrays.m4
+++ b/gl/m4/vararrays.m4
@@ -1,13 +1,14 @@
-# Check for variable-length arrays.
-
+# vararrays.m4
 # serial 6
+dnl Copyright (C) 2001, 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-# From Paul Eggert
+# Check for variable-length arrays.
 
-# Copyright (C) 2001, 2009-2023 Free Software Foundation, Inc.
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
+# From Paul Eggert
 
 m4_version_prereq([2.70], [], [
 
diff --git a/gl/m4/vasnprintf.m4 b/gl/m4/vasnprintf.m4
index 6361c843..1d040d6e 100644
--- a/gl/m4/vasnprintf.m4
+++ b/gl/m4/vasnprintf.m4
@@ -1,13 +1,47 @@
-# vasnprintf.m4 serial 38
-dnl Copyright (C) 2002-2004, 2006-2023 Free Software Foundation, Inc.
+# vasnprintf.m4
+# serial 56
+dnl Copyright (C) 2002-2004, 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_VASNPRINTF],
 [
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_CHECK_FUNCS_ONCE([vasnprintf])
-  if test $ac_cv_func_vasnprintf = no; then
+  if test $ac_cv_func_vasnprintf = yes; then
+    dnl On Cygwin, in directives with a huge width, the width is ignored, and
+    dnl the function returns a wrong result.
+    AC_CACHE_CHECK([whether vasnprintf works],
+      [gl_cv_func_vasnprintf_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE(
+            [[#include <stdio.h>
+            ]],
+            [[size_t len;
+              char *res = vasnprintf (NULL, &len, "x%03000000000dy\n", -17);
+              /* On Cygwin 3.4.6, res is "x-17y\n" and len == 6: wrong.  */
+              return (res != NULL && len < 10);
+            ]])
+         ],
+         [gl_cv_func_vasnprintf_works=yes],
+         [gl_cv_func_vasnprintf_works=no],
+         [case "$host_os" in
+                     # Guess no on Cygwin.
+            cygwin*) gl_cv_func_vasnprintf_works="guessing no";;
+                     # If we don't know, obey --enable-cross-guesses.
+            *)       gl_cv_func_vasnprintf_works="$gl_cross_guess_normal";;
+          esac
+         ])
+      ])
+  fi
+  if test $ac_cv_func_vasnprintf != yes \
+     || case "$gl_cv_func_vasnprintf_works" in
+          *yes) false;;
+          *)    true;;
+        esac
+  then
     gl_REPLACE_VASNPRINTF
   fi
 ])
@@ -29,18 +63,26 @@ AC_DEFUN([gl_REPLACE_VASNPRINTF],
   gl_PREREQ_ASNPRINTF
 ])
 
+AC_DEFUN([gl_FUNC_VASNWPRINTF],
+[
+  AC_LIBOBJ([printf-args])
+  gl_PREREQ_PRINTF_ARGS
+  gl_PREREQ_PRINTF_PARSE
+  gl_PREREQ_VASNWPRINTF
+  gl_PREREQ_ASNPRINTF
+])
+
 # Prerequisites of lib/printf-args.h, lib/printf-args.c.
 AC_DEFUN([gl_PREREQ_PRINTF_ARGS],
 [
-  AC_REQUIRE([gt_TYPE_WCHAR_T])
   AC_REQUIRE([gt_TYPE_WINT_T])
 ])
 
 # Prerequisites of lib/printf-parse.h, lib/printf-parse.c.
+# Prerequisites of lib/wprintf-parse.h, lib/wprintf-parse.c.
 AC_DEFUN([gl_PREREQ_PRINTF_PARSE],
 [
   AC_REQUIRE([gl_FEATURES_H])
-  AC_REQUIRE([gt_TYPE_WCHAR_T])
   AC_REQUIRE([gt_TYPE_WINT_T])
   AC_REQUIRE([AC_TYPE_SIZE_T])
   AC_CHECK_TYPE([ptrdiff_t], ,
@@ -50,19 +92,13 @@ AC_DEFUN([gl_PREREQ_PRINTF_PARSE],
   AC_REQUIRE([gt_AC_TYPE_INTMAX_T])
 ])
 
-# Prerequisites of lib/vasnprintf.c.
+# Prerequisites of lib/vasnprintf.c if !WIDE_CHAR_VERSION.
 AC_DEFUN_ONCE([gl_PREREQ_VASNPRINTF],
 [
-  AC_REQUIRE([AC_FUNC_ALLOCA])
-  AC_REQUIRE([gt_TYPE_WCHAR_T])
-  AC_REQUIRE([gt_TYPE_WINT_T])
-  AC_CHECK_FUNCS([snprintf strnlen wcslen wcsnlen mbrtowc wcrtomb])
+  AC_CHECK_FUNCS([snprintf strnlen wcrtomb])
   dnl Use the _snprintf function only if it is declared (because on NetBSD it
   dnl is defined as a weak alias of snprintf; we prefer to use the latter).
   AC_CHECK_DECLS([_snprintf], , , [[#include <stdio.h>]])
-  dnl Knowing DBL_EXPBIT0_WORD and DBL_EXPBIT0_BIT enables an optimization
-  dnl in the code for NEED_PRINTF_LONG_DOUBLE || NEED_PRINTF_DOUBLE.
-  AC_REQUIRE([gl_DOUBLE_EXPONENT_LOCATION])
   dnl We can avoid a lot of code by assuming that snprintf's return value
   dnl conforms to ISO C99. So check that.
   AC_REQUIRE([gl_SNPRINTF_RETVAL_C99])
@@ -84,6 +120,107 @@ AC_DEFUN_ONCE([gl_PREREQ_VASNPRINTF],
          terminated.])
       ;;
   esac
+  gl_PREREQ_VASNXPRINTF
+])
+
+# Prerequisites of lib/vasnwprintf.c.
+AC_DEFUN_ONCE([gl_PREREQ_VASNWPRINTF],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_FUNCS_ONCE([swprintf wcsnlen mbrtowc])
+  AC_CHECK_DECLS([_snwprintf], , , [[#include <stdio.h>]])
+  AC_CHECK_DECLS([wcsnlen], , , [[#include <wchar.h>]])
+  gl_SWPRINTF_WORKS
+  case "$gl_cv_func_swprintf_works" in
+    *yes)
+      AC_DEFINE([HAVE_WORKING_SWPRINTF], [1],
+        [Define if the swprintf function works correctly when it produces output
+         that contains null wide characters.])
+      ;;
+  esac
+  gl_MBRTOWC_C_LOCALE
+  case "$gl_cv_func_mbrtowc_C_locale_sans_EILSEQ" in
+    *yes)
+      AC_CACHE_CHECK([whether swprintf in the C locale is free of encoding errors],
+        [gl_cv_func_swprintf_C_locale_sans_EILSEQ],
+        [
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#ifndef __USE_MINGW_ANSI_STDIO
+# define __USE_MINGW_ANSI_STDIO 1
+#endif
+#include <stdio.h>
+#include <wchar.h>
+int main()
+{
+  int result = 0;
+  { /* This test fails on glibc 2.35, musl libc 1.2.4, FreeBSD 13.2, NetBSD 9.3,
+       OpenBSD 7.2, Cygwin 2.9.0.
+       Reported at <https://www.openwall.com/lists/musl/2023/06/12/2>.  */
+    wchar_t buf[12];
+    int ret = swprintf (buf, 12, L"%c", '\377');
+    if (ret < 0)
+      result |= 1;
+  }
+  return result;
+}]])],
+            [gl_cv_func_swprintf_C_locale_sans_EILSEQ=yes],
+            [gl_cv_func_swprintf_C_locale_sans_EILSEQ=no],
+            [case "$host_os" in
+                                   # Guess no on glibc systems.
+               *-gnu* | gnu*)      gl_cv_func_swprintf_C_locale_sans_EILSEQ="guessing yes";;
+                                   # Guess no on musl systems.
+               *-musl* | midipix*) gl_cv_func_swprintf_C_locale_sans_EILSEQ="guessing no";;
+                                   # If we don't know, obey --enable-cross-guesses.
+               *)                  gl_cv_func_swprintf_C_locale_sans_EILSEQ="$gl_cross_guess_normal";;
+             esac
+            ])
+        ])
+      ;;
+  esac
+  if case "$gl_cv_func_mbrtowc_C_locale_sans_EILSEQ" in
+       *yes) false ;;
+       *) true ;;
+     esac \
+     || case "$gl_cv_func_swprintf_C_locale_sans_EILSEQ" in
+          *yes) false ;;
+          *) true ;;
+        esac; then
+    AC_DEFINE([NEED_WPRINTF_DIRECTIVE_C], [1],
+      [Define if the vasnwprintf implementation needs special code for
+       the 'c' directive.])
+  fi
+  gl_SWPRINTF_DIRECTIVE_LA
+  case "$gl_cv_func_swprintf_directive_la" in
+    *yes) ;;
+    *)
+      AC_DEFINE([NEED_WPRINTF_DIRECTIVE_LA], [1],
+        [Define if the vasnwprintf implementation needs special code for
+         the 'a' directive with 'long double' arguments.])
+      ;;
+  esac
+  gl_SWPRINTF_DIRECTIVE_LC
+  case "$gl_cv_func_swprintf_directive_lc" in
+    *yes) ;;
+    *)
+      AC_DEFINE([NEED_WPRINTF_DIRECTIVE_LC], [1],
+        [Define if the vasnwprintf implementation needs special code for
+         the 'lc' directive.])
+      ;;
+  esac
+  gl_MUSL_LIBC
+  gl_PREREQ_VASNXPRINTF
+])
+
+# Common prerequisites of lib/vasnprintf.c and lib/vasnwprintf.c.
+AC_DEFUN_ONCE([gl_PREREQ_VASNXPRINTF],
+[
+  AC_REQUIRE([AC_FUNC_ALLOCA])
+  AC_REQUIRE([gt_TYPE_WINT_T])
+  AC_CHECK_FUNCS([wcslen])
+  dnl Knowing DBL_EXPBIT0_WORD and DBL_EXPBIT0_BIT enables an optimization
+  dnl in the code for NEED_PRINTF_LONG_DOUBLE || NEED_PRINTF_DOUBLE.
+  AC_REQUIRE([gl_DOUBLE_EXPONENT_LOCATION])
 ])
 
 # Extra prerequisites of lib/vasnprintf.c for supporting 'long double'
@@ -152,7 +289,22 @@ AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_A],
       AC_DEFINE([NEED_PRINTF_DIRECTIVE_A], [1],
         [Define if the vasnprintf implementation needs special code for
          the 'a' and 'A' directives.])
-      AC_CHECK_FUNCS([nl_langinfo])
+      gl_CHECK_FUNCS_ANDROID([nl_langinfo], [[#include <langinfo.h>]])
+      ;;
+  esac
+])
+
+# Extra prerequisites of lib/vasnprintf.c for supporting the 'b' directive.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_B],
+[
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_B])
+  case "$gl_cv_func_printf_directive_b" in
+    *yes)
+      ;;
+    *)
+      AC_DEFINE([NEED_PRINTF_DIRECTIVE_B], [1],
+        [Define if the vasnprintf implementation needs special code for
+         the 'b' directive.])
       ;;
   esac
 ])
@@ -187,18 +339,57 @@ AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_LS],
   esac
 ])
 
-# Extra prerequisites of lib/vasnprintf.c for supporting the ' flag.
-AC_DEFUN([gl_PREREQ_VASNPRINTF_FLAG_GROUPING],
+# Extra prerequisites of lib/vasnprintf.c for supporting the 'lc' directive.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_LC],
 [
-  AC_REQUIRE([gl_PRINTF_FLAG_GROUPING])
-  case "$gl_cv_func_printf_flag_grouping" in
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_LC])
+  case "$gl_cv_func_printf_directive_lc" in
     *yes)
       ;;
     *)
+      AC_DEFINE([NEED_PRINTF_DIRECTIVE_LC], [1],
+        [Define if the vasnprintf implementation needs special code for
+         the 'lc' directive.])
+      ;;
+  esac
+])
+
+# Extra prerequisites of lib/vasnprintf.c for supporting the ' flag.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_FLAG_GROUPING],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_PRINTF_FLAG_GROUPING])
+  AC_REQUIRE([gl_PRINTF_FLAG_GROUPING_INT_PRECISION])
+  AC_REQUIRE([gl_PRINTF_FLAG_GROUPING_MULTIBYTE])
+  case "$host_os" in
+    mingw* | windows*)
+      dnl MSVC does not support the ' flag at all.
+      dnl mingw does not support it, unless __USE_MINGW_ANSI_STDIO is defined.
+      dnl mingw also has other bugs regarding the ' flag.
       AC_DEFINE([NEED_PRINTF_FLAG_GROUPING], [1],
         [Define if the vasnprintf implementation needs special code for the
          ' flag.])
       ;;
+    *)
+      case "$gl_cv_func_printf_flag_grouping,$gl_cv_func_printf_flag_grouping_multibyte" in
+        *yes,*yes)
+          case "$gl_cv_func_printf_flag_grouping_int_precision" in
+            *yes)
+              ;;
+            *)
+              AC_DEFINE([NEED_PRINTF_FLAG_GROUPING_INT], [1],
+                [Define if the vasnprintf implementation needs special code for the
+                 ' flag, for integer directives only.])
+              ;;
+          esac
+          ;;
+        *)
+          AC_DEFINE([NEED_PRINTF_FLAG_GROUPING], [1],
+            [Define if the vasnprintf implementation needs special code for the
+             ' flag.])
+          ;;
+      esac
+      ;;
   esac
 ])
 
@@ -232,6 +423,22 @@ AC_DEFUN([gl_PREREQ_VASNPRINTF_FLAG_ZERO],
   esac
 ])
 
+# Extra prerequisites of lib/vasnprintf.c for supporting the # flag with a
+# zero precision and a zero value in the 'x' and 'X' directives.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_FLAG_ALT_PRECISION_ZERO],
+[
+  AC_REQUIRE([gl_PRINTF_FLAG_ALT_PRECISION_ZERO])
+  case "$gl_cv_func_printf_flag_alt_precision_zero" in
+    *yes)
+      ;;
+    *)
+      AC_DEFINE([NEED_PRINTF_FLAG_ALT_PRECISION_ZERO], [1],
+        [Define if the vasnprintf implementation needs special code for the
+         # flag with a zero precision and a zero value in the 'x' and 'X' directives.])
+      ;;
+  esac
+])
+
 # Extra prerequisites of lib/vasnprintf.c for supporting large precisions.
 AC_DEFUN([gl_PREREQ_VASNPRINTF_PRECISION],
 [
@@ -276,23 +483,53 @@ AC_DEFUN([gl_PREREQ_VASNPRINTF_ENOMEM],
 ])
 
 # Prerequisites of lib/vasnprintf.c including all extras for POSIX compliance.
-AC_DEFUN([gl_PREREQ_VASNPRINTF_WITH_EXTRAS],
+AC_DEFUN([gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS],
 [
   AC_REQUIRE([gl_PREREQ_VASNPRINTF])
   gl_PREREQ_VASNPRINTF_LONG_DOUBLE
   gl_PREREQ_VASNPRINTF_INFINITE_DOUBLE
   gl_PREREQ_VASNPRINTF_INFINITE_LONG_DOUBLE
   gl_PREREQ_VASNPRINTF_DIRECTIVE_A
+  gl_PREREQ_VASNPRINTF_DIRECTIVE_B
   gl_PREREQ_VASNPRINTF_DIRECTIVE_F
   gl_PREREQ_VASNPRINTF_DIRECTIVE_LS
+  gl_PREREQ_VASNPRINTF_DIRECTIVE_LC
   gl_PREREQ_VASNPRINTF_FLAG_GROUPING
   gl_PREREQ_VASNPRINTF_FLAG_LEFTADJUST
   gl_PREREQ_VASNPRINTF_FLAG_ZERO
+  gl_PREREQ_VASNPRINTF_FLAG_ALT_PRECISION_ZERO
   gl_PREREQ_VASNPRINTF_PRECISION
   gl_PREREQ_VASNPRINTF_ENOMEM
 ])
 
+# Extra prerequisites of lib/vasnprintf.c for supporting the 'B' directive.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_DIRECTIVE_UPPERCASE_B],
+[
+  AC_REQUIRE([gl_PRINTF_DIRECTIVE_UPPERCASE_B])
+  case "$gl_cv_func_printf_directive_uppercase_b" in
+    *yes)
+      ;;
+    *)
+      AC_DEFINE([NEED_PRINTF_DIRECTIVE_UPPERCASE_B], [1],
+        [Define if the vasnprintf implementation needs special code for
+         the 'B' directive.])
+      ;;
+  esac
+])
+
+# Prerequisites of lib/vasnprintf.c including all extras for POSIX compliance
+# and GNU compatibility.
+AC_DEFUN([gl_PREREQ_VASNPRINTF_WITH_GNU_EXTRAS],
+[
+  gl_PREREQ_VASNPRINTF_WITH_POSIX_EXTRAS
+  AC_DEFINE([SUPPORT_GNU_PRINTF_DIRECTIVES], [1],
+    [Define if the vasnprintf implementation should support GNU compatible
+     printf directives.])
+  gl_PREREQ_VASNPRINTF_DIRECTIVE_UPPERCASE_B
+])
+
 # Prerequisites of lib/asnprintf.c.
+# Prerequisites of lib/asnwprintf.c.
 AC_DEFUN([gl_PREREQ_ASNPRINTF],
 [
 ])
diff --git a/gl/m4/vasprintf.m4 b/gl/m4/vasprintf.m4
index 6e6156a7..6ea602bd 100644
--- a/gl/m4/vasprintf.m4
+++ b/gl/m4/vasprintf.m4
@@ -1,9 +1,11 @@
-# vasprintf.m4 serial 6
-dnl Copyright (C) 2002-2003, 2006-2007, 2009-2023 Free Software Foundation,
+# vasprintf.m4
+# serial 6
+dnl Copyright (C) 2002-2003, 2006-2007, 2009-2025 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_VASPRINTF],
 [
diff --git a/gl/m4/visibility.m4 b/gl/m4/visibility.m4
index f0468e89..c2cd38d0 100644
--- a/gl/m4/visibility.m4
+++ b/gl/m4/visibility.m4
@@ -1,8 +1,10 @@
-# visibility.m4 serial 8
-dnl Copyright (C) 2005, 2008, 2010-2023 Free Software Foundation, Inc.
+# visibility.m4
+# serial 9
+dnl Copyright (C) 2005, 2008, 2010-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 
@@ -31,18 +33,18 @@ AC_DEFUN([gl_VISIBILITY],
     dnl user has put into $CC $CFLAGS $CPPFLAGS.
     AC_CACHE_CHECK([whether the -Werror option is usable],
       [gl_cv_cc_vis_werror],
-      [gl_save_CFLAGS="$CFLAGS"
+      [gl_saved_CFLAGS="$CFLAGS"
        CFLAGS="$CFLAGS -Werror"
        AC_COMPILE_IFELSE(
          [AC_LANG_PROGRAM([[]], [[]])],
          [gl_cv_cc_vis_werror=yes],
          [gl_cv_cc_vis_werror=no])
-       CFLAGS="$gl_save_CFLAGS"
+       CFLAGS="$gl_saved_CFLAGS"
       ])
     dnl Now check whether visibility declarations are supported.
     AC_CACHE_CHECK([for simple visibility declarations],
       [gl_cv_cc_visibility],
-      [gl_save_CFLAGS="$CFLAGS"
+      [gl_saved_CFLAGS="$CFLAGS"
        CFLAGS="$CFLAGS -fvisibility=hidden"
        dnl We use the option -Werror and a function dummyfunc, because on some
        dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning
@@ -68,7 +70,7 @@ AC_DEFUN([gl_VISIBILITY],
             [[]])],
          [gl_cv_cc_visibility=yes],
          [gl_cv_cc_visibility=no])
-       CFLAGS="$gl_save_CFLAGS"
+       CFLAGS="$gl_saved_CFLAGS"
       ])
     if test $gl_cv_cc_visibility = yes; then
       CFLAG_VISIBILITY="-fvisibility=hidden"
diff --git a/gl/m4/vsnprintf.m4 b/gl/m4/vsnprintf.m4
index 7fbb11c4..68ab757d 100644
--- a/gl/m4/vsnprintf.m4
+++ b/gl/m4/vsnprintf.m4
@@ -1,8 +1,10 @@
-# vsnprintf.m4 serial 7
-dnl Copyright (C) 2002-2004, 2007-2023 Free Software Foundation, Inc.
+# vsnprintf.m4
+# serial 7
+dnl Copyright (C) 2002-2004, 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Libintl 0.17 will replace vsnprintf only if it does not support %1$s,
 dnl but defers to any gnulib vsnprintf replacements.  Therefore, gnulib
diff --git a/gl/m4/warn-on-use.m4 b/gl/m4/warn-on-use.m4
index 10649c5c..73cf16fb 100644
--- a/gl/m4/warn-on-use.m4
+++ b/gl/m4/warn-on-use.m4
@@ -1,8 +1,10 @@
-# warn-on-use.m4 serial 10
-dnl Copyright (C) 2010-2023 Free Software Foundation, Inc.
+# warn-on-use.m4
+# serial 11
+dnl Copyright (C) 2010-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 # gl_WARN_ON_USE_PREPARE(INCLUDES, NAMES)
 # ---------------------------------------
@@ -36,7 +38,7 @@ AC_DEFUN([gl_WARN_ON_USE_PREPARE],
        dnl clang (e.g. strndup), reference ac_compile_for_check_decl instead
        dnl of ac_compile.  If, for whatever reason, the override of AC_PROG_CC
        dnl in zzgnulib.m4 is inactive, use the original ac_compile.
-       ac_save_ac_compile="$ac_compile"
+       ac_saved_ac_compile="$ac_compile"
        if test -n "$ac_compile_for_check_decl"; then
          ac_compile="$ac_compile_for_check_decl"
        fi
@@ -46,7 +48,7 @@ AC_DEFUN([gl_WARN_ON_USE_PREPARE],
 [[#undef $gl_func
   (void) $gl_func;]])],
            [AS_VAR_SET([gl_Symbol], [yes])], [AS_VAR_SET([gl_Symbol], [no])])])
-       ac_compile="$ac_save_ac_compile"
+       ac_compile="$ac_saved_ac_compile"
        AS_VAR_IF([gl_Symbol], [yes],
          [AC_DEFINE_UNQUOTED(AS_TR_CPP([HAVE_RAW_DECL_$gl_func]), [1])
           dnl Shortcut for an AC_CHECK_DECL invocation that may come later:
diff --git a/gl/m4/wchar_h.m4 b/gl/m4/wchar_h.m4
index 8ec66193..722fcfc2 100644
--- a/gl/m4/wchar_h.m4
+++ b/gl/m4/wchar_h.m4
@@ -1,13 +1,14 @@
-dnl A placeholder for ISO C99 <wchar.h>, for platforms that have issues.
-
-dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
+# wchar_h.m4
+# serial 65
+dnl Copyright (C) 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
-dnl Written by Eric Blake.
+dnl A placeholder for ISO C99 <wchar.h>, for platforms that have issues.
 
-# wchar_h.m4 serial 55
+dnl Written by Eric Blake.
 
 AC_DEFUN_ONCE([gl_WCHAR_H],
 [
@@ -86,8 +87,8 @@ AC_DEFUN([gl_WCHAR_H_INLINE_OK],
          dnl z/OS when using the XPLINK object format (due to duplicate
          dnl CSECT names). Instead, temporarily redefine $ac_compile so
          dnl that the object file has the latter name from the start.
-         save_ac_compile="$ac_compile"
-         ac_compile=`echo "$save_ac_compile" | sed s/conftest/conftest1/`
+         saved_ac_compile="$ac_compile"
+         ac_compile=`echo "$saved_ac_compile" | sed s/conftest/conftest1/`
          if echo '#include "conftest.c"' >conftest1.c \
             && AC_TRY_EVAL([ac_compile]); then
            AC_LANG_CONFTEST([
@@ -97,7 +98,7 @@ AC_DEFUN([gl_WCHAR_H_INLINE_OK],
                int zero (void) { return 0; }
              ]])])
            dnl See note above about renaming object files.
-           ac_compile=`echo "$save_ac_compile" | sed s/conftest/conftest2/`
+           ac_compile=`echo "$saved_ac_compile" | sed s/conftest/conftest2/`
            if echo '#include "conftest.c"' >conftest2.c \
               && AC_TRY_EVAL([ac_compile]); then
              if $CC -o conftest$ac_exeext $CFLAGS $LDFLAGS conftest1.$ac_objext conftest2.$ac_objext $LIBS >&AS_MESSAGE_LOG_FD 2>&1; then
@@ -107,7 +108,7 @@ AC_DEFUN([gl_WCHAR_H_INLINE_OK],
              fi
            fi
          fi
-         ac_compile="$save_ac_compile"
+         ac_compile="$saved_ac_compile"
          rm -f conftest[12].c conftest[12].$ac_objext conftest$ac_exeext
          ;;
      esac
@@ -147,6 +148,7 @@ AC_DEFUN([gl_WCHAR_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_BTOWC])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCTOB])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSINIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSZERO])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBRTOWC])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBRLEN])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MBSRTOWCS])
@@ -185,6 +187,7 @@ AC_DEFUN([gl_WCHAR_H_REQUIRE_DEFAULTS],
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSTOK])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSWIDTH])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCSFTIME])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WGETCWD])
     dnl Support Microsoft deprecated alias function names by default.
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_MDA_WCSDUP], [1])
   ])
@@ -253,5 +256,11 @@ AC_DEFUN([gl_WCHAR_H_DEFAULTS],
   REPLACE_WCWIDTH=0;    AC_SUBST([REPLACE_WCWIDTH])
   REPLACE_WCSWIDTH=0;   AC_SUBST([REPLACE_WCSWIDTH])
   REPLACE_WCSFTIME=0;   AC_SUBST([REPLACE_WCSFTIME])
+  REPLACE_WCSCMP=0;     AC_SUBST([REPLACE_WCSCMP])
+  REPLACE_WCSNCAT=0;    AC_SUBST([REPLACE_WCSNCAT])
+  REPLACE_WCSNCMP=0;    AC_SUBST([REPLACE_WCSNCMP])
+  REPLACE_WCSSTR=0;     AC_SUBST([REPLACE_WCSSTR])
   REPLACE_WCSTOK=0;     AC_SUBST([REPLACE_WCSTOK])
+  REPLACE_WMEMCMP=0;    AC_SUBST([REPLACE_WMEMCMP])
+  REPLACE_WMEMPCPY=0;   AC_SUBST([REPLACE_WMEMPCPY])
 ])
diff --git a/gl/m4/wchar_t.m4 b/gl/m4/wchar_t.m4
deleted file mode 100644
index 50bde08a..00000000
--- a/gl/m4/wchar_t.m4
+++ /dev/null
@@ -1,24 +0,0 @@
-# wchar_t.m4 serial 4 (gettext-0.18.2)
-dnl Copyright (C) 2002-2003, 2008-2023 Free Software Foundation, Inc.
-dnl This file is free software; the Free Software Foundation
-dnl gives unlimited permission to copy and/or distribute it,
-dnl with or without modifications, as long as this notice is preserved.
-
-dnl From Bruno Haible.
-dnl Test whether <stddef.h> has the 'wchar_t' type.
-dnl Prerequisite: AC_PROG_CC
-
-AC_DEFUN([gt_TYPE_WCHAR_T],
-[
-  AC_CACHE_CHECK([for wchar_t], [gt_cv_c_wchar_t],
-    [AC_COMPILE_IFELSE(
-       [AC_LANG_PROGRAM(
-          [[#include <stddef.h>
-            wchar_t foo = (wchar_t)'\0';]],
-          [[]])],
-       [gt_cv_c_wchar_t=yes],
-       [gt_cv_c_wchar_t=no])])
-  if test $gt_cv_c_wchar_t = yes; then
-    AC_DEFINE([HAVE_WCHAR_T], [1], [Define if you have the 'wchar_t' type.])
-  fi
-])
diff --git a/gl/m4/wcrtomb.m4 b/gl/m4/wcrtomb.m4
index d51b36e1..91530176 100644
--- a/gl/m4/wcrtomb.m4
+++ b/gl/m4/wcrtomb.m4
@@ -1,8 +1,10 @@
-# wcrtomb.m4 serial 17
-dnl Copyright (C) 2008-2023 Free Software Foundation, Inc.
+# wcrtomb.m4
+# serial 21
+dnl Copyright (C) 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_WCRTOMB],
 [
@@ -35,7 +37,7 @@ AC_DEFUN([gl_FUNC_WCRTOMB],
       dnl sometimes returns 0 instead of 1.
       AC_REQUIRE([AC_PROG_CC])
       AC_REQUIRE([gt_LOCALE_FR])
-      AC_REQUIRE([gt_LOCALE_FR_UTF8])
+      AC_REQUIRE([gt_LOCALE_EN_UTF8])
       AC_REQUIRE([gt_LOCALE_JA])
       AC_REQUIRE([gt_LOCALE_ZH_CN])
       AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
@@ -82,12 +84,14 @@ int main ()
 changequote(,)dnl
           case "$host_os" in
             # Guess no on AIX 4, OSF/1, Solaris, native Windows.
-            aix4* | osf* | solaris* | mingw*) gl_cv_func_wcrtomb_retval="guessing no" ;;
+            aix4* | osf* | solaris* | mingw* | windows*)
+              gl_cv_func_wcrtomb_retval="guessing no" ;;
             # Guess yes otherwise.
-            *)                                gl_cv_func_wcrtomb_retval="guessing yes" ;;
+            *)
+              gl_cv_func_wcrtomb_retval="guessing yes" ;;
           esac
 changequote([,])dnl
-          if test $LOCALE_FR != none || test $LOCALE_FR_UTF8 != none || test $LOCALE_JA != none || test $LOCALE_ZH_CN != none; then
+          if test $LOCALE_FR != none || test "$LOCALE_EN_UTF8" != none || test $LOCALE_JA != none || test $LOCALE_ZH_CN != none; then
             AC_RUN_IFELSE(
               [AC_LANG_SOURCE([[
 #include <locale.h>
@@ -97,12 +101,14 @@ changequote([,])dnl
 int main ()
 {
   int result = 0;
-  if (setlocale (LC_ALL, "$LOCALE_FR") != NULL)
+  if (strcmp ("$LOCALE_FR", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_FR") != NULL)
     {
       if (wcrtomb (NULL, 0, NULL) != 1)
         result |= 1;
     }
-  if (setlocale (LC_ALL, "$LOCALE_FR_UTF8") != NULL)
+  if (strcmp ("$LOCALE_EN_UTF8", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_EN_UTF8") != NULL)
     {
       if (wcrtomb (NULL, 0, NULL) != 1)
         result |= 2;
@@ -113,12 +119,14 @@ int main ()
             result |= 2;
       }
     }
-  if (setlocale (LC_ALL, "$LOCALE_JA") != NULL)
+  if (strcmp ("$LOCALE_JA", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_JA") != NULL)
     {
       if (wcrtomb (NULL, 0, NULL) != 1)
         result |= 4;
     }
-  if (setlocale (LC_ALL, "$LOCALE_ZH_CN") != NULL)
+  if (strcmp ("$LOCALE_ZH_CN", "none") != 0
+      && setlocale (LC_ALL, "$LOCALE_ZH_CN") != NULL)
     {
       if (wcrtomb (NULL, 0, NULL) != 1)
         result |= 8;
diff --git a/gl/m4/wctype.m4 b/gl/m4/wctype.m4
new file mode 100644
index 00000000..56593cd5
--- /dev/null
+++ b/gl/m4/wctype.m4
@@ -0,0 +1,53 @@
+# wctype.m4
+# serial 6
+dnl Copyright (C) 2011-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_FUNC_WCTYPE],
+[
+  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
+  AC_REQUIRE([gl_WCTYPE_H])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  HAVE_WCTYPE=$HAVE_WCTYPE_T
+  if test $HAVE_WCTYPE = 1; then
+    AC_CACHE_CHECK([whether wctype supports the "blank" and "punct" character classes],
+      [gl_cv_func_wctype_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE([[
+            #include <ctype.h>
+            #include <wchar.h>
+            #include <wctype.h>
+            int main ()
+            {
+              /* This test fails on mingw.  */
+              if (wctype ("blank") == (wctype_t)0)
+                return 1;
+              /* This test fails on MSVC 14.  */
+              if ((! iswctype ('\t', wctype ("blank"))) != (! iswblank ('\t')))
+                return 2;
+              /* This test fails on Android 11.  */
+              if ((! iswctype ('\`', wctype ("punct"))) != (! ispunct ('\`')))
+                return 4;
+              return 0;
+            }
+         ]])],
+         [gl_cv_func_wctype_works=yes], [gl_cv_func_wctype_works=no],
+         [case "$host_os" in
+                               # Guess no on native Windows.
+            mingw* | windows*) gl_cv_func_wctype_works="guessing no" ;;
+                               # Guess no on Android.
+            android*)          gl_cv_func_wctype_works="guessing no" ;;
+                               # Guess yes otherwise.
+            *)                 gl_cv_func_wctype_works="guessing yes" ;;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_wctype_works" in
+      *yes) ;;
+      *) REPLACE_WCTYPE=1 ;;
+    esac
+  fi
+])
diff --git a/gl/m4/wctype_h.m4 b/gl/m4/wctype_h.m4
index 6856a735..8e54678d 100644
--- a/gl/m4/wctype_h.m4
+++ b/gl/m4/wctype_h.m4
@@ -1,11 +1,13 @@
-# wctype_h.m4 serial 30
+# wctype_h.m4
+# serial 33
 
 dnl A placeholder for ISO C99 <wctype.h>, for platforms that lack it.
 
-dnl Copyright (C) 2006-2023 Free Software Foundation, Inc.
+dnl Copyright (C) 2006-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl Written by Paul Eggert.
 
@@ -178,6 +180,7 @@ AC_DEFUN([gl_WCTYPE_H_REQUIRE_DEFAULTS],
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_WCTYPE_H_MODULE_INDICATOR_DEFAULTS], [
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWBLANK])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWDIGIT])
+    gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWPUNCT])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWXDIGIT])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_WCTYPE])
     gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_ISWCTYPE])
@@ -196,5 +199,8 @@ AC_DEFUN([gl_WCTYPE_H_DEFAULTS],
   HAVE_WCTRANS_T=1;     AC_SUBST([HAVE_WCTRANS_T])
   REPLACE_ISWBLANK=0;   AC_SUBST([REPLACE_ISWBLANK])
   REPLACE_ISWDIGIT=0;   AC_SUBST([REPLACE_ISWDIGIT])
+  REPLACE_ISWPUNCT=0;   AC_SUBST([REPLACE_ISWPUNCT])
   REPLACE_ISWXDIGIT=0;  AC_SUBST([REPLACE_ISWXDIGIT])
+  REPLACE_WCTRANS=0;    AC_SUBST([REPLACE_WCTRANS])
+  REPLACE_WCTYPE=0;     AC_SUBST([REPLACE_WCTYPE])
 ])
diff --git a/gl/m4/wcwidth.m4 b/gl/m4/wcwidth.m4
new file mode 100644
index 00000000..2cc6ebb1
--- /dev/null
+++ b/gl/m4/wcwidth.m4
@@ -0,0 +1,116 @@
+# wcwidth.m4
+# serial 38
+dnl Copyright (C) 2006-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_WCWIDTH],
+[
+  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  dnl Persuade glibc <wchar.h> to declare wcwidth().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_REQUIRE([gt_TYPE_WINT_T])
+
+  AC_CHECK_HEADERS_ONCE([wchar.h])
+  AC_CHECK_FUNCS_ONCE([wcwidth])
+
+  AC_CHECK_DECLS([wcwidth], [], [], [[
+    #include <wchar.h>
+  ]])
+  if test $ac_cv_have_decl_wcwidth != yes; then
+    HAVE_DECL_WCWIDTH=0
+  fi
+
+  if test $ac_cv_func_wcwidth != yes; then
+    AC_CACHE_CHECK([whether wcwidth is a macro],
+      [gl_cv_func_wcwidth_macro],
+      [AC_EGREP_CPP([wchar_header_defines_wcwidth], [
+#include <wchar.h>
+#ifdef wcwidth
+ wchar_header_defines_wcwidth
+#endif],
+         [gl_cv_func_wcwidth_macro=yes],
+         [gl_cv_func_wcwidth_macro=no])
+      ])
+  fi
+
+  if test $ac_cv_func_wcwidth = yes || test $gl_cv_func_wcwidth_macro = yes; then
+    HAVE_WCWIDTH=1
+    dnl On Mac OS X 10.3, wcwidth(0x0301) (COMBINING ACUTE ACCENT) returns 1.
+    dnl On macOS 12.5, NetBSD 9.3, OpenBSD 5.0, MidnightBSD 1.1,
+    dnl wcwidth(0x05B0) (HEBREW POINT SHEVA) returns 1.
+    dnl On macOS 12.5, NetBSD 9.3, MidnightBSD 1.1, OSF/1 5.1,
+    dnl wcwidth(0x200B) (ZERO WIDTH SPACE) returns 1.
+    dnl On OpenBSD 5.8, wcwidth(0xFF1A) (FULLWIDTH COLON) returns 0.
+    dnl This leads to bugs in 'ls' (coreutils).
+    dnl On Solaris 11.4, wcwidth(0x2202) (PARTIAL DIFFERENTIAL) returns 2,
+    dnl even in Western locales.
+    AC_CACHE_CHECK([whether wcwidth works reasonably in UTF-8 locales],
+      [gl_cv_func_wcwidth_works],
+      [
+        AC_RUN_IFELSE(
+          [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <wchar.h>
+#if !HAVE_DECL_WCWIDTH
+extern
+# ifdef __cplusplus
+"C"
+# endif
+int wcwidth (int);
+#endif
+int main ()
+{
+  int result = 0;
+  if (setlocale (LC_ALL, "en_US.UTF-8") != NULL)
+    {
+      if (wcwidth (0x0301) > 0)
+        result |= 1;
+      if (wcwidth (0x05B0) > 0)
+        result |= 2;
+      if (wcwidth (0x200B) > 0)
+        result |= 4;
+      if (wcwidth (0xFF1A) == 0)
+        result |= 8;
+      if (wcwidth (0x2202) > 1)
+        result |= 16;
+    }
+  return result;
+}]])],
+          [gl_cv_func_wcwidth_works=yes],
+          [gl_cv_func_wcwidth_works=no],
+          [
+changequote(,)dnl
+           case "$host_os" in
+                                 # Guess yes on glibc systems.
+             *-gnu* | gnu*)      gl_cv_func_wcwidth_works="guessing yes";;
+                                 # Guess yes on musl systems.
+             *-musl* | midipix*) gl_cv_func_wcwidth_works="guessing yes";;
+                                 # Guess yes on AIX 7 systems.
+             aix[7-9]*)          gl_cv_func_wcwidth_works="guessing yes";;
+             *)                  gl_cv_func_wcwidth_works="$gl_cross_guess_normal";;
+           esac
+changequote([,])dnl
+          ])
+      ])
+    case "$gl_cv_func_wcwidth_works" in
+      *yes) ;;
+      *no) REPLACE_WCWIDTH=1 ;;
+    esac
+  else
+    HAVE_WCWIDTH=0
+  fi
+  dnl We don't substitute HAVE_WCWIDTH. We assume that if the system does not
+  dnl have the wcwidth function, then it does not declare it.
+])
+
+# Prerequisites of lib/wcwidth.c.
+AC_DEFUN([gl_PREREQ_WCWIDTH], [
+  AC_REQUIRE([AC_C_INLINE])
+  :
+])
diff --git a/gl/m4/wint_t.m4 b/gl/m4/wint_t.m4
index dfd743b3..8a3c7944 100644
--- a/gl/m4/wint_t.m4
+++ b/gl/m4/wint_t.m4
@@ -1,8 +1,10 @@
-# wint_t.m4 serial 11
-dnl Copyright (C) 2003, 2007-2023 Free Software Foundation, Inc.
+# wint_t.m4
+# serial 11
+dnl Copyright (C) 2003, 2007-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl From Bruno Haible.
 dnl Test whether <wchar.h> has the 'wint_t' type and whether gnulib's
diff --git a/gl/m4/xalloc.m4 b/gl/m4/xalloc.m4
index fc56f59a..c10c4189 100644
--- a/gl/m4/xalloc.m4
+++ b/gl/m4/xalloc.m4
@@ -1,7 +1,9 @@
-# xalloc.m4 serial 18
-dnl Copyright (C) 2002-2006, 2009-2023 Free Software Foundation, Inc.
+# xalloc.m4
+# serial 18
+dnl Copyright (C) 2002-2006, 2009-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_XALLOC], [:])
diff --git a/gl/m4/xsize.m4 b/gl/m4/xsize.m4
index 649db9c5..157d635c 100644
--- a/gl/m4/xsize.m4
+++ b/gl/m4/xsize.m4
@@ -1,8 +1,10 @@
-# xsize.m4 serial 5
-dnl Copyright (C) 2003-2004, 2008-2023 Free Software Foundation, Inc.
+# xsize.m4
+# serial 5
+dnl Copyright (C) 2003-2004, 2008-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_XSIZE],
 [
diff --git a/gl/m4/zzgnulib.m4 b/gl/m4/zzgnulib.m4
index 362102b6..343bda5c 100644
--- a/gl/m4/zzgnulib.m4
+++ b/gl/m4/zzgnulib.m4
@@ -1,8 +1,10 @@
-# zzgnulib.m4 serial 1
-dnl Copyright (C) 2020-2023 Free Software Foundation, Inc.
+# zzgnulib.m4
+# serial 1
+dnl Copyright (C) 2020-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 dnl This file must be named something that sorts after all other
 dnl package- or gnulib-provided .m4 files - at least for those packages