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# 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_saved_CFLAGS=$CFLAGS
for gl_working in "yes, a keyword" "yes, an <assert.h> macro"; do
AS_CASE([$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],
[yes*keyword*],
[AC_DEFINE([HAVE_C_STATIC_ASSERT], [1],
[Define to 1 if the static_assert keyword works.])],
[no],
[GL_GENERATE_ASSERT_H=true
gl_NEXT_HEADERS([assert.h])])
dnl The "zz" puts this toward config.h's end, to avoid potential
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 __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.
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
#endif])
])
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