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mirror of https://git.savannah.gnu.org/git/emacs.git synced 2024-11-30 08:09:04 +00:00
emacs/m4/stddef_h.m4
Eli Zaretskii dcd76bd48d Merge from origin/emacs-28
836be7a112 ; * etc/refcards/ru-refcard.tex: Update Copyright year.
86cbc6ee4a * lisp/net/tramp-sh.el: Adapt copyright year
ebe8772f65 ; Minor fixes related to copyright years
23c1ee6989 ; * test/manual/etags/ETAGS.good_N: Adjust to copyright ye...
8d3fc7ec89 * src/xfaces.c (face_for_font): Make 'hash' be uintptr_t.
19dcb237b5 ; Add 2022 to copyright years.

# Conflicts:
#	etc/NEWS
#	etc/refcards/ru-refcard.tex
#	lib/cdefs.h
#	lisp/erc/erc-dcc.el
#	lisp/erc/erc-imenu.el
#	lisp/erc/erc-replace.el
#	lisp/image-dired.el
#	lisp/progmodes/xref.el
#	m4/alloca.m4
#	m4/byteswap.m4
#	m4/errno_h.m4
#	m4/getopt.m4
#	m4/gnulib-common.m4
#	m4/inttypes.m4
#	m4/stddef_h.m4
#	m4/stdint.m4
#	m4/sys_socket_h.m4
2022-01-01 07:03:03 -05:00

98 lines
3.6 KiB
Plaintext

# stddef_h.m4 serial 12
dnl Copyright (C) 2009-2022 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])
])