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-rw-r--r--gnulib_m4/stddef_h.m4104
1 files changed, 104 insertions, 0 deletions
diff --git a/gnulib_m4/stddef_h.m4 b/gnulib_m4/stddef_h.m4
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+# stddef_h.m4 serial 13
+dnl Copyright (C) 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.
+
+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])
+
+ GL_GENERATE_STDDEF_H=false
+
+ dnl Test whether the type max_align_t exists and whether its alignment
+ dnl "is as great as is supported by the implementation in all contexts".
+ AC_CACHE_CHECK([for good max_align_t],
+ [gl_cv_type_max_align_t],
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[/* On FreeBSD 12.0/x86, max_align_t defined by <stddef.h> has
+ the correct alignment with the default (wrong) definition of
+ _Alignof, but a wrong alignment as soon as we activate an
+ ISO C compliant _Alignof definition. */
+ #if ((defined __GNUC__ && 4 <= __GNUC__) || defined __clang__) && !defined __cplusplus
+ #define _Alignof(type) __builtin_offsetof (struct { char __a; type __b; }, __b)
+ #endif
+ #include <stddef.h>
+ unsigned int s = sizeof (max_align_t);
+ #if defined __GNUC__ || defined __clang__ || defined __IBM__ALIGNOF__
+ int check1[2 * (__alignof__ (double) <= __alignof__ (max_align_t)) - 1];
+ int check2[2 * (__alignof__ (long double) <= __alignof__ (max_align_t)) - 1];
+ #endif
+ typedef struct { char a; max_align_t b; } max_helper;
+ typedef struct { char a; long b; } long_helper;
+ typedef struct { char a; double b; } double_helper;
+ typedef struct { char a; long double b; } long_double_helper;
+ int check3[2 * (offsetof (long_helper, b) <= offsetof (max_helper, b)) - 1];
+ int check4[2 * (offsetof (double_helper, b) <= offsetof (max_helper, b)) - 1];
+ int check5[2 * (offsetof (long_double_helper, b) <= offsetof (max_helper, b)) - 1];
+ ]])],
+ [gl_cv_type_max_align_t=yes],
+ [gl_cv_type_max_align_t=no])
+ ])
+ if test $gl_cv_type_max_align_t = no; then
+ HAVE_MAX_ALIGN_T=0
+ 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>
+ int test[2 * (sizeof NULL == sizeof (void *)) -1];
+]])],
+ [gl_cv_decl_null_works=yes],
+ [gl_cv_decl_null_works=no])])
+ if test $gl_cv_decl_null_works = no; then
+ REPLACE_NULL=1
+ GL_GENERATE_STDDEF_H=true
+ fi
+
+ if $GL_GENERATE_STDDEF_H; then
+ gl_NEXT_HEADERS([stddef.h])
+ fi
+])
+
+# gl_STDDEF_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_STDDEF_MODULE_INDICATOR],
+[
+ dnl Ensure to expand the default settings once only.
+ gl_STDDEF_H_REQUIRE_DEFAULTS
+ gl_MODULE_INDICATOR_SET_VARIABLE([$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_STDDEF_H_REQUIRE_DEFAULTS],
+[
+ m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDDEF_H_MODULE_INDICATOR_DEFAULTS], [
+ ])
+ m4_require(GL_MODULE_INDICATOR_PREFIX[_STDDEF_H_MODULE_INDICATOR_DEFAULTS])
+ AC_REQUIRE([gl_STDDEF_H_DEFAULTS])
+])
+
+AC_DEFUN([gl_STDDEF_H_DEFAULTS],
+[
+ dnl Assume proper GNU behavior unless another module says otherwise.
+ 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])
+])