1dnl A placeholder for <stddef.h>, for platforms that have issues.
2# stddef_h.m4 serial 7
3dnl Copyright (C) 2009-2020 Free Software Foundation, Inc.
4dnl This file is free software; the Free Software Foundation
5dnl gives unlimited permission to copy and/or distribute it,
6dnl with or without modifications, as long as this notice is preserved.
7
8AC_DEFUN([gl_STDDEF_H],
9[
10  AC_REQUIRE([gl_STDDEF_H_DEFAULTS])
11  AC_REQUIRE([gt_TYPE_WCHAR_T])
12  STDDEF_H=
13
14  dnl Test whether the type max_align_t exists and whether its alignment
15  dnl "is as great as is supported by the implementation in all contexts".
16  AC_CACHE_CHECK([for good max_align_t],
17    [gl_cv_type_max_align_t],
18    [AC_COMPILE_IFELSE(
19       [AC_LANG_PROGRAM(
20          [[#include <stddef.h>
21            unsigned int s = sizeof (max_align_t);
22            #if defined __GNUC__ || defined __clang__ || defined __IBM__ALIGNOF__
23            int check1[2 * (__alignof__ (double) <= __alignof__ (max_align_t)) - 1];
24            int check2[2 * (__alignof__ (long double) <= __alignof__ (max_align_t)) - 1];
25            #endif
26          ]])],
27       [gl_cv_type_max_align_t=yes],
28       [gl_cv_type_max_align_t=no])
29    ])
30  if test $gl_cv_type_max_align_t = no; then
31    HAVE_MAX_ALIGN_T=0
32    STDDEF_H=stddef.h
33  fi
34
35  if test $gt_cv_c_wchar_t = no; then
36    HAVE_WCHAR_T=0
37    STDDEF_H=stddef.h
38  fi
39
40  AC_CACHE_CHECK([whether NULL can be used in arbitrary expressions],
41    [gl_cv_decl_null_works],
42    [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stddef.h>
43      int test[2 * (sizeof NULL == sizeof (void *)) -1];
44]])],
45      [gl_cv_decl_null_works=yes],
46      [gl_cv_decl_null_works=no])])
47  if test $gl_cv_decl_null_works = no; then
48    REPLACE_NULL=1
49    STDDEF_H=stddef.h
50  fi
51
52  AC_SUBST([STDDEF_H])
53  AM_CONDITIONAL([GL_GENERATE_STDDEF_H], [test -n "$STDDEF_H"])
54  if test -n "$STDDEF_H"; then
55    gl_NEXT_HEADERS([stddef.h])
56  fi
57])
58
59AC_DEFUN([gl_STDDEF_MODULE_INDICATOR],
60[
61  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
62  AC_REQUIRE([gl_STDDEF_H_DEFAULTS])
63  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
64])
65
66AC_DEFUN([gl_STDDEF_H_DEFAULTS],
67[
68  dnl Assume proper GNU behavior unless another module says otherwise.
69  REPLACE_NULL=0;                AC_SUBST([REPLACE_NULL])
70  HAVE_MAX_ALIGN_T=1;            AC_SUBST([HAVE_MAX_ALIGN_T])
71  HAVE_WCHAR_T=1;                AC_SUBST([HAVE_WCHAR_T])
72])
73