mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-12-11 09:20:51 +00:00
98 lines
3.6 KiB
Plaintext
98 lines
3.6 KiB
Plaintext
# stddef_h.m4 serial 12
|
|
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(
|
|
[[#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])
|
|
])
|