1 files changed, 59 insertions, 34 deletions

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