1 files changed, 35 insertions, 14 deletions

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])
 ])