1 files changed, 73 insertions, 0 deletions
diff --git a/m4/assert_h.m4 b/m4/assert_h.m4
new file mode 100644
index 0000000..d255855
--- /dev/null
+++ b/m4/assert_h.m4
@@ -0,0 +1,73 @@
+# assert-h.m4
+dnl Copyright (C) 2011-2023 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 Paul Eggert.
+
+AC_DEFUN([gl_ASSERT_H],
+[
+  AC_CACHE_CHECK([for static_assert], [gl_cv_static_assert],
+    [gl_save_CFLAGS=$CFLAGS
+     for gl_working in "yes, a keyword" "yes, an <assert.h> macro"; do
+      AS_CASE([$gl_working],
+        [*assert.h*], [CFLAGS="$gl_save_CFLAGS -DINCLUDE_ASSERT_H"])
+
+      AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#if defined __clang__ && __STDC_VERSION__ < 202311
+             #pragma clang diagnostic error "-Wc2x-extensions"
+             #pragma clang diagnostic error "-Wc++1z-extensions"
+            #endif
+            #ifdef INCLUDE_ASSERT_H
+             #include <assert.h>
+            #endif
+            static_assert (2 + 2 == 4, "arithmetic does not work");
+            static_assert (2 + 2 == 4);
+          ]],
+          [[
+            static_assert (sizeof (char) == 1, "sizeof does not work");
+            static_assert (sizeof (char) == 1);
+          ]])],
+       [gl_cv_static_assert=$gl_working],
+       [gl_cv_static_assert=no])
+      CFLAGS=$gl_save_CFLAGS
+      test "$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 #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 \
+     && (!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
+  #undef/**/static_assert
+  #define static_assert _Static_assert
+ #endif
+#endif])
+])