1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
# stddef_h.m4
# serial 17
dnl Copyright (C) 2009-2024 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])
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
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
AC_CACHE_CHECK([for unreachable],
[gl_cv_func_unreachable],
[AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#include <stddef.h>
]],
[[unreachable ();
]])],
[gl_cv_func_unreachable=yes],
[gl_cv_func_unreachable=no])
])
if test $gl_cv_func_unreachable = no; then
GL_GENERATE_STDDEF_H=true
fi
dnl https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114869
AC_CACHE_CHECK([whether nullptr_t needs <stddef.h>],
[gl_cv_nullptr_t_needs_stddef],
[AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[nullptr_t x;]],
[gl_cv_nullptr_t_needs_stddef=no],
[gl_cv_nullptr_t_needs_stddef=yes])])
if test "$gl_cv_nullptr_t_needs_stddef" = no; then
NULLPTR_T_NEEDS_STDDEF=0
GL_GENERATE_STDDEF_H=true
fi
AC_CACHE_CHECK([for clean definition of __STDC_VERSION_STDDEF_H__],
[gl_cv_clean_version_stddef],
[AC_PREPROC_IFELSE(
[AC_LANG_SOURCE(
[[/* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114870 */
#include <stddef.h>
#undef __STDC_VERSION_STDDEF_H__
#include <time.h>
#ifdef __STDC_VERSION_STDDEF_H__
# error "<time.h> defines __STDC_VERSION_STDDEF_H__"
#endif
]])],
[gl_cv_clean_version_stddef=yes],
[gl_cv_clean_version_stddef=no])])
if test "$gl_cv_clean_version_stddef" = no; then
STDDEF_NOT_IDEMPOTENT=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.
NULLPTR_T_NEEDS_STDDEF=1; AC_SUBST([NULLPTR_T_NEEDS_STDDEF])
STDDEF_NOT_IDEMPOTENT=0; AC_SUBST([STDDEF_NOT_IDEMPOTENT])
REPLACE_NULL=0; AC_SUBST([REPLACE_NULL])
HAVE_MAX_ALIGN_T=1; AC_SUBST([HAVE_MAX_ALIGN_T])
])
|
