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emacs/lib/stddef.in.h

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/* A substitute for POSIX 2008 <stddef.h>, for platforms that have issues.
Copyright (C) 2009-2024 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Eric Blake. */
/*
* POSIX 2008 and ISO C 23 <stddef.h> for platforms that have issues.
* <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stddef.h.html>
*/
#if __GNUC__ >= 3
@PRAGMA_SYSTEM_HEADER@
#endif
@PRAGMA_COLUMNS@
#if (defined __need_wchar_t || defined __need_size_t \
|| defined __need_ptrdiff_t || defined __need_NULL \
|| defined __need_wint_t) \
/* Avoid warning triggered by "gcc -std=gnu23 -Wsystem-headers" \
in Fedora 40 with gcc 14.0.1. \
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114870>. */ \
&& !@STDDEF_NOT_IDEMPOTENT@
/* Special invocation convention inside gcc header files. In
particular, <stddef.h> in some ancient versions of GCC blindly
redefined NULL when __need_wint_t was defined, even though wint_t
is not normally provided by <stddef.h>.
(FIXME: It's not clear what GCC versions those were - perhaps so
ancient that we can stop worrying about this?)
Although glibc 2.26 (2017) and later do not use __need_wint_t,
for portability to macOS, Cygwin, Haiku, and older Glibc + GCC,
remember if special invocation has ever been used to obtain wint_t,
in which case we need to clean up NULL yet again. */
# if !(defined _@GUARD_PREFIX@_STDDEF_H && defined _@GUARD_PREFIX@_STDDEF_WINT_T)
# ifdef __need_wint_t
# define _@GUARD_PREFIX@_STDDEF_WINT_T
# endif
# @INCLUDE_NEXT@ @NEXT_STDDEF_H@
/* On TinyCC, make sure that the macros that indicate the special invocation
convention get undefined. */
# undef __need_wchar_t
# undef __need_size_t
# undef __need_ptrdiff_t
# undef __need_NULL
# undef __need_wint_t
# endif
#else
/* For @STDDEF_NOT_IDEMPOTENT@. */
# undef __need_wchar_t
# undef __need_size_t
# undef __need_ptrdiff_t
# undef __need_NULL
# undef __need_wint_t
/* Normal invocation convention. */
# ifndef _@GUARD_PREFIX@_STDDEF_H
/* On AIX 7.2, with xlc in 64-bit mode, <stddef.h> defines max_align_t to a
type with alignment 4, but 'long' has alignment 8. */
# if defined _AIX && defined __LP64__ && !@HAVE_MAX_ALIGN_T@
# if !GNULIB_defined_max_align_t
# ifdef _MAX_ALIGN_T
/* /usr/include/stddef.h has already defined max_align_t. Override it. */
typedef long rpl_max_align_t;
# define max_align_t rpl_max_align_t
# else
/* Prevent /usr/include/stddef.h from defining max_align_t. */
typedef long max_align_t;
# define _MAX_ALIGN_T
# endif
# define __CLANG_MAX_ALIGN_T_DEFINED
# define GNULIB_defined_max_align_t 1
# endif
# endif
# if !defined _GCC_NULLPTR_T && !@NULLPTR_T_NEEDS_STDDEF@
/* Suppress unwanted nullptr_t typedef. See
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114869>. */
# define _GCC_NULLPTR_T
# endif
/* The include_next requires a split double-inclusion guard. */
# @INCLUDE_NEXT@ @NEXT_STDDEF_H@
/* On NetBSD 5.0, the definition of NULL lacks proper parentheses. */
# if (@REPLACE_NULL@ \
&& (!defined _@GUARD_PREFIX@_STDDEF_H || defined _@GUARD_PREFIX@_STDDEF_WINT_T))
# undef NULL
# ifdef __cplusplus
/* ISO C++ says that the macro NULL must expand to an integer constant
expression, hence '((void *) 0)' is not allowed in C++. */
# if __GNUG__ >= 3
/* GNU C++ has a __null macro that behaves like an integer ('int' or
'long') but has the same size as a pointer. Use that, to avoid
warnings. */
# define NULL __null
# else
# define NULL 0L
# endif
# else
# define NULL ((void *) 0)
# endif
# endif
# ifndef _@GUARD_PREFIX@_STDDEF_H
# define _@GUARD_PREFIX@_STDDEF_H
/* This file uses _Noreturn, _GL_ATTRIBUTE_NOTHROW. */
#if !_GL_CONFIG_H_INCLUDED
#error "Please include config.h first."
#endif
/* _GL_ATTRIBUTE_NOTHROW declares that the function does not throw exceptions.
*/
#ifndef _GL_ATTRIBUTE_NOTHROW
# if defined __cplusplus
# if (__GNUC__ + (__GNUC_MINOR__ >= 8) > 2) || __clang_major >= 4
# if __cplusplus >= 201103L
# define _GL_ATTRIBUTE_NOTHROW noexcept (true)
# else
# define _GL_ATTRIBUTE_NOTHROW throw ()
# endif
# else
# define _GL_ATTRIBUTE_NOTHROW
# endif
# else
# if (__GNUC__ + (__GNUC_MINOR__ >= 3) > 3) || defined __clang__
# define _GL_ATTRIBUTE_NOTHROW __attribute__ ((__nothrow__))
# else
# define _GL_ATTRIBUTE_NOTHROW
# endif
# endif
#endif
/* Some platforms lack wchar_t. */
#if !@HAVE_WCHAR_T@
# define wchar_t int
#endif
/* Some platforms lack max_align_t. The check for _GCC_MAX_ALIGN_T is
a hack in case the configure-time test was done with g++ even though
we are currently compiling with gcc.
On MSVC, max_align_t is defined only in C++ mode, after <cstddef> was
included. Its definition is good since it has an alignment of 8 (on x86
and x86_64).
Similarly on OS/2 kLIBC. */
#if (defined _MSC_VER || (defined __KLIBC__ && !defined __LIBCN__)) \
&& defined __cplusplus
# include <cstddef>
#else
# if ! (@HAVE_MAX_ALIGN_T@ || (defined _GCC_MAX_ALIGN_T && !defined __clang__))
# if !GNULIB_defined_max_align_t
/* On the x86, the maximum storage alignment of double, long, etc. is 4,
but GCC's C11 ABI for x86 says that max_align_t has an alignment of 8,
and the C11 standard allows this. Work around this problem by
using __alignof__ (which returns 8 for double) rather than _Alignof
(which returns 4), and align each union member accordingly. */
# if defined __GNUC__ || (__clang_major__ >= 4)
# define _GL_STDDEF_ALIGNAS(type) \
__attribute__ ((__aligned__ (__alignof__ (type))))
# else
# define _GL_STDDEF_ALIGNAS(type) /* */
# endif
typedef union
{
char *__p _GL_STDDEF_ALIGNAS (char *);
double __d _GL_STDDEF_ALIGNAS (double);
long double __ld _GL_STDDEF_ALIGNAS (long double);
long int __i _GL_STDDEF_ALIGNAS (long int);
} rpl_max_align_t;
# define max_align_t rpl_max_align_t
# define __CLANG_MAX_ALIGN_T_DEFINED
# define GNULIB_defined_max_align_t 1
# endif
# endif
#endif
/* ISO C 23 § 7.21.1 The unreachable macro */
#ifndef unreachable
/* Code borrowed from verify.h. */
# ifndef _GL_HAS_BUILTIN_UNREACHABLE
# if defined __clang_major__ && __clang_major__ < 5
# define _GL_HAS_BUILTIN_UNREACHABLE 0
# elif 4 < __GNUC__ + (5 <= __GNUC_MINOR__)
# define _GL_HAS_BUILTIN_UNREACHABLE 1
# elif defined __has_builtin
# define _GL_HAS_BUILTIN_UNREACHABLE __has_builtin (__builtin_unreachable)
# else
# define _GL_HAS_BUILTIN_UNREACHABLE 0
# endif
# endif
# if _GL_HAS_BUILTIN_UNREACHABLE
# define unreachable() __builtin_unreachable ()
# elif 1200 <= _MSC_VER
# define unreachable() __assume (0)
# else
/* Declare abort(), without including <stdlib.h>. */
extern
# if defined __cplusplus
"C"
# endif
_Noreturn
void abort (void)
# if defined __cplusplus && (__GLIBC__ >= 2)
_GL_ATTRIBUTE_NOTHROW
# endif
;
# define unreachable() abort ()
# endif
#endif
# endif /* _@GUARD_PREFIX@_STDDEF_H */
# endif /* _@GUARD_PREFIX@_STDDEF_H */
#endif /* __need_XXX */
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