stddef.h: Add C2x unreachable macro

[thirdparty/gcc.git] / gcc / ginclude / stddef.h

/* Copyright (C) 1989-2022 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC 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 General Public License for more details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */

/*
 * ISO C Standard:  7.17  Common definitions  <stddef.h>
 */
#if (!defined(_STDDEF_H) && !defined(_STDDEF_H_) && !defined(_ANSI_STDDEF_H) \
     && !defined(__STDDEF_H__)) \
    || defined(__need_wchar_t) || defined(__need_size_t) \
    || defined(__need_ptrdiff_t) || defined(__need_NULL) \
    || defined(__need_wint_t)

/* Any one of these symbols __need_* means that GNU libc
   wants us just to define one data type.  So don't define
   the symbols that indicate this file's entire job has been done.  */
#if (!defined(__need_wchar_t) && !defined(__need_size_t)	\
     && !defined(__need_ptrdiff_t) && !defined(__need_NULL)	\
     && !defined(__need_wint_t))
#define _STDDEF_H
#define _STDDEF_H_
/* snaroff@next.com says the NeXT needs this.  */
#define _ANSI_STDDEF_H
#endif

#ifndef __sys_stdtypes_h
/* This avoids lossage on SunOS but only if stdtypes.h comes first.
   There's no way to win with the other order!  Sun lossage.  */

#if defined(__NetBSD__)
#include <machine/ansi.h>
#endif

#if defined (__FreeBSD__)
#include <sys/_types.h>
#endif

#if defined(__NetBSD__)
#if !defined(_SIZE_T_) && !defined(_BSD_SIZE_T_)
#define _SIZE_T
#endif
#if !defined(_PTRDIFF_T_) && !defined(_BSD_PTRDIFF_T_)
#define _PTRDIFF_T
#endif
/* On BSD/386 1.1, at least, machine/ansi.h defines _BSD_WCHAR_T_
   instead of _WCHAR_T_. */
#if !defined(_WCHAR_T_) && !defined(_BSD_WCHAR_T_)
#ifndef _BSD_WCHAR_T_
#define _WCHAR_T
#endif
#endif
/* Undef _FOO_T_ if we are supposed to define foo_t.  */
#if defined (__need_ptrdiff_t) || defined (_STDDEF_H_)
#undef _PTRDIFF_T_
#undef _BSD_PTRDIFF_T_
#endif
#if defined (__need_size_t) || defined (_STDDEF_H_)
#undef _SIZE_T_
#undef _BSD_SIZE_T_
#endif
#if defined (__need_wchar_t) || defined (_STDDEF_H_)
#undef _WCHAR_T_
#undef _BSD_WCHAR_T_
#endif
#endif /* defined(__NetBSD__) */

/* Sequent's header files use _PTRDIFF_T_ in some conflicting way.
   Just ignore it.  */
#if defined (__sequent__) && defined (_PTRDIFF_T_)
#undef _PTRDIFF_T_
#endif

/* On VxWorks, <type/vxTypesBase.h> may have defined macros like
   _TYPE_size_t which will typedef size_t.  fixincludes patched the
   vxTypesBase.h so that this macro is only defined if _GCC_SIZE_T is
   not defined, and so that defining this macro defines _GCC_SIZE_T.
   If we find that the macros are still defined at this point, we must
   invoke them so that the type is defined as expected.  */
#if defined (_TYPE_ptrdiff_t) && (defined (__need_ptrdiff_t) || defined (_STDDEF_H_))
_TYPE_ptrdiff_t;
#undef _TYPE_ptrdiff_t
#endif
#if defined (_TYPE_size_t) && (defined (__need_size_t) || defined (_STDDEF_H_))
_TYPE_size_t;
#undef _TYPE_size_t
#endif
#if defined (_TYPE_wchar_t) && (defined (__need_wchar_t) || defined (_STDDEF_H_))
_TYPE_wchar_t;
#undef _TYPE_wchar_t
#endif

/* In case nobody has defined these types, but we aren't running under
   GCC 2.00, make sure that __PTRDIFF_TYPE__, __SIZE_TYPE__, and
   __WCHAR_TYPE__ have reasonable values.  This can happen if the
   parts of GCC is compiled by an older compiler, that actually
   include gstddef.h, such as collect2.  */

/* Signed type of difference of two pointers.  */

/* Define this type if we are doing the whole job,
   or if we want this type in particular.  */
#if defined (_STDDEF_H) || defined (__need_ptrdiff_t)
#ifndef _PTRDIFF_T	/* in case <sys/types.h> has defined it. */
#ifndef _T_PTRDIFF_
#ifndef _T_PTRDIFF
#ifndef __PTRDIFF_T
#ifndef _PTRDIFF_T_
#ifndef _BSD_PTRDIFF_T_
#ifndef ___int_ptrdiff_t_h
#ifndef _GCC_PTRDIFF_T
#ifndef _PTRDIFF_T_DECLARED /* DragonFly */
#ifndef __DEFINED_ptrdiff_t /* musl libc */
#define _PTRDIFF_T
#define _T_PTRDIFF_
#define _T_PTRDIFF
#define __PTRDIFF_T
#define _PTRDIFF_T_
#define _BSD_PTRDIFF_T_
#define ___int_ptrdiff_t_h
#define _GCC_PTRDIFF_T
#define _PTRDIFF_T_DECLARED
#define __DEFINED_ptrdiff_t
#ifndef __PTRDIFF_TYPE__
#define __PTRDIFF_TYPE__ long int
#endif
typedef __PTRDIFF_TYPE__ ptrdiff_t;
#endif /* __DEFINED_ptrdiff_t */
#endif /* _PTRDIFF_T_DECLARED */
#endif /* _GCC_PTRDIFF_T */
#endif /* ___int_ptrdiff_t_h */
#endif /* _BSD_PTRDIFF_T_ */
#endif /* _PTRDIFF_T_ */
#endif /* __PTRDIFF_T */
#endif /* _T_PTRDIFF */
#endif /* _T_PTRDIFF_ */
#endif /* _PTRDIFF_T */

/* If this symbol has done its job, get rid of it.  */
#undef	__need_ptrdiff_t

#endif /* _STDDEF_H or __need_ptrdiff_t.  */

/* Unsigned type of `sizeof' something.  */

/* Define this type if we are doing the whole job,
   or if we want this type in particular.  */
#if defined (_STDDEF_H) || defined (__need_size_t)
#ifndef __size_t__	/* BeOS */
#ifndef __SIZE_T__	/* Cray Unicos/Mk */
#ifndef _SIZE_T	/* in case <sys/types.h> has defined it. */
#ifndef _SYS_SIZE_T_H
#ifndef _T_SIZE_
#ifndef _T_SIZE
#ifndef __SIZE_T
#ifndef _SIZE_T_
#ifndef _BSD_SIZE_T_
#ifndef _SIZE_T_DEFINED_
#ifndef _SIZE_T_DEFINED
#ifndef _BSD_SIZE_T_DEFINED_	/* Darwin */
#ifndef _SIZE_T_DECLARED	/* FreeBSD 5 */
#ifndef __DEFINED_size_t	/* musl libc */
#ifndef ___int_size_t_h
#ifndef _GCC_SIZE_T
#ifndef _SIZET_
#ifndef __size_t
#define __size_t__	/* BeOS */
#define __SIZE_T__	/* Cray Unicos/Mk */
#define _SIZE_T
#define _SYS_SIZE_T_H
#define _T_SIZE_
#define _T_SIZE
#define __SIZE_T
#define _SIZE_T_
#define _BSD_SIZE_T_
#define _SIZE_T_DEFINED_
#define _SIZE_T_DEFINED
#define _BSD_SIZE_T_DEFINED_	/* Darwin */
#define _SIZE_T_DECLARED	/* FreeBSD 5 */
#define __DEFINED_size_t	/* musl libc */
#define ___int_size_t_h
#define _GCC_SIZE_T
#define _SIZET_
#if defined (__FreeBSD__) \
  || defined(__DragonFly__) \
  || defined(__FreeBSD_kernel__) \
  || defined(__VMS__)
/* __size_t is a typedef, must not trash it.  */
#else
#define __size_t
#endif
#ifndef __SIZE_TYPE__
#define __SIZE_TYPE__ long unsigned int
#endif
#if !(defined (__GNUG__) && defined (size_t))
typedef __SIZE_TYPE__ size_t;
#ifdef __BEOS__
typedef long ssize_t;
#endif /* __BEOS__ */
#endif /* !(defined (__GNUG__) && defined (size_t)) */
#endif /* __size_t */
#endif /* _SIZET_ */
#endif /* _GCC_SIZE_T */
#endif /* ___int_size_t_h */
#endif /* __DEFINED_size_t */
#endif /* _SIZE_T_DECLARED */
#endif /* _BSD_SIZE_T_DEFINED_ */
#endif /* _SIZE_T_DEFINED */
#endif /* _SIZE_T_DEFINED_ */
#endif /* _BSD_SIZE_T_ */
#endif /* _SIZE_T_ */
#endif /* __SIZE_T */
#endif /* _T_SIZE */
#endif /* _T_SIZE_ */
#endif /* _SYS_SIZE_T_H */
#endif /* _SIZE_T */
#endif /* __SIZE_T__ */
#endif /* __size_t__ */
#undef	__need_size_t
#endif /* _STDDEF_H or __need_size_t.  */


/* Wide character type.
   Locale-writers should change this as necessary to
   be big enough to hold unique values not between 0 and 127,
   and not (wchar_t) -1, for each defined multibyte character.  */

/* Define this type if we are doing the whole job,
   or if we want this type in particular.  */
#if defined (_STDDEF_H) || defined (__need_wchar_t)
#ifndef __wchar_t__	/* BeOS */
#ifndef __WCHAR_T__	/* Cray Unicos/Mk */
#ifndef _WCHAR_T
#ifndef _T_WCHAR_
#ifndef _T_WCHAR
#ifndef __WCHAR_T
#ifndef _WCHAR_T_
#ifndef _BSD_WCHAR_T_
#ifndef _BSD_WCHAR_T_DEFINED_    /* Darwin */
#ifndef _BSD_RUNE_T_DEFINED_	/* Darwin */
#ifndef _WCHAR_T_DECLARED /* FreeBSD 5 */
#ifndef __DEFINED_wchar_t /* musl libc */
#ifndef _WCHAR_T_DEFINED_
#ifndef _WCHAR_T_DEFINED
#ifndef _WCHAR_T_H
#ifndef ___int_wchar_t_h
#ifndef __INT_WCHAR_T_H
#ifndef _GCC_WCHAR_T
#define __wchar_t__	/* BeOS */
#define __WCHAR_T__	/* Cray Unicos/Mk */
#define _WCHAR_T
#define _T_WCHAR_
#define _T_WCHAR
#define __WCHAR_T
#define _WCHAR_T_
#define _BSD_WCHAR_T_
#define _WCHAR_T_DEFINED_
#define _WCHAR_T_DEFINED
#define _WCHAR_T_H
#define ___int_wchar_t_h
#define __INT_WCHAR_T_H
#define _GCC_WCHAR_T
#define _WCHAR_T_DECLARED
#define __DEFINED_wchar_t

/* On BSD/386 1.1, at least, machine/ansi.h defines _BSD_WCHAR_T_
   instead of _WCHAR_T_, and _BSD_RUNE_T_ (which, unlike the other
   symbols in the _FOO_T_ family, stays defined even after its
   corresponding type is defined).  If we define wchar_t, then we
   must undef _WCHAR_T_; for BSD/386 1.1 (and perhaps others), if
   we undef _WCHAR_T_, then we must also define rune_t, since 
   headers like runetype.h assume that if machine/ansi.h is included,
   and _BSD_WCHAR_T_ is not defined, then rune_t is available.
   machine/ansi.h says, "Note that _WCHAR_T_ and _RUNE_T_ must be of
   the same type." */
#ifdef _BSD_WCHAR_T_
#undef _BSD_WCHAR_T_
#ifdef _BSD_RUNE_T_
#if !defined (_ANSI_SOURCE) && !defined (_POSIX_SOURCE)
typedef _BSD_RUNE_T_ rune_t;
#define _BSD_WCHAR_T_DEFINED_
#define _BSD_RUNE_T_DEFINED_	/* Darwin */
#if defined (__FreeBSD__) && (__FreeBSD__ < 5)
/* Why is this file so hard to maintain properly?  In contrast to
   the comment above regarding BSD/386 1.1, on FreeBSD for as long
   as the symbol has existed, _BSD_RUNE_T_ must not stay defined or
   redundant typedefs will occur when stdlib.h is included after this file. */
#undef _BSD_RUNE_T_
#endif
#endif
#endif
#endif
/* FreeBSD 5 can't be handled well using "traditional" logic above
   since it no longer defines _BSD_RUNE_T_ yet still desires to export
   rune_t in some cases... */
#if defined (__FreeBSD__) && (__FreeBSD__ >= 5)
#if !defined (_ANSI_SOURCE) && !defined (_POSIX_SOURCE)
#if __BSD_VISIBLE
#ifndef _RUNE_T_DECLARED
typedef __rune_t        rune_t;
#define _RUNE_T_DECLARED
#endif
#endif
#endif
#endif

#ifndef __WCHAR_TYPE__
#define __WCHAR_TYPE__ int
#endif
#ifndef __cplusplus
typedef __WCHAR_TYPE__ wchar_t;
#endif
#endif
#endif
#endif
#endif
#endif
#endif
#endif /* __DEFINED_wchar_t */
#endif /* _WCHAR_T_DECLARED */
#endif /* _BSD_RUNE_T_DEFINED_ */
#endif
#endif
#endif
#endif
#endif
#endif
#endif
#endif /* __WCHAR_T__ */
#endif /* __wchar_t__ */
#undef	__need_wchar_t
#endif /* _STDDEF_H or __need_wchar_t.  */

#if defined (__need_wint_t)
#ifndef _WINT_T
#define _WINT_T

#ifndef __WINT_TYPE__
#define __WINT_TYPE__ unsigned int
#endif
typedef __WINT_TYPE__ wint_t;
#endif
#undef __need_wint_t
#endif

#if defined(__NetBSD__)
/*  The references to _GCC_PTRDIFF_T_, _GCC_SIZE_T_, and _GCC_WCHAR_T_
    are probably typos and should be removed before 2.8 is released.  */
#ifdef _GCC_PTRDIFF_T_
#undef _PTRDIFF_T_
#undef _BSD_PTRDIFF_T_
#endif
#ifdef _GCC_SIZE_T_
#undef _SIZE_T_
#undef _BSD_SIZE_T_
#endif
#ifdef _GCC_WCHAR_T_
#undef _WCHAR_T_
#undef _BSD_WCHAR_T_
#endif
/*  The following ones are the real ones.  */
#ifdef _GCC_PTRDIFF_T
#undef _PTRDIFF_T_
#undef _BSD_PTRDIFF_T_
#endif
#ifdef _GCC_SIZE_T
#undef _SIZE_T_
#undef _BSD_SIZE_T_
#endif
#ifdef _GCC_WCHAR_T
#undef _WCHAR_T_
#undef _BSD_WCHAR_T_
#endif
#endif /* __NetBSD__ */

#endif /* __sys_stdtypes_h */

/* A null pointer constant.  */

#if defined (_STDDEF_H) || defined (__need_NULL)
#undef NULL		/* in case <stdio.h> has defined it. */
#ifdef __GNUG__
#define NULL __null
#else   /* G++ */
#ifndef __cplusplus
#define NULL ((void *)0)
#else   /* C++ */
#define NULL 0
#endif  /* C++ */
#endif  /* G++ */
#endif	/* NULL not defined and <stddef.h> or need NULL.  */
#undef	__need_NULL

#ifdef _STDDEF_H

/* Offset of member MEMBER in a struct of type TYPE. */
#define offsetof(TYPE, MEMBER) __builtin_offsetof (TYPE, MEMBER)

#if (defined (__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) \
  || (defined(__cplusplus) && __cplusplus >= 201103L)
#ifndef _GCC_MAX_ALIGN_T
#define _GCC_MAX_ALIGN_T
/* Type whose alignment is supported in every context and is at least
   as great as that of any standard type not using alignment
   specifiers.  */
typedef struct {
  long long __max_align_ll __attribute__((__aligned__(__alignof__(long long))));
  long double __max_align_ld __attribute__((__aligned__(__alignof__(long double))));
  /* _Float128 is defined as a basic type, so max_align_t must be
     sufficiently aligned for it.  This code must work in C++, so we
     use __float128 here; that is only available on some
     architectures, but only on i386 is extra alignment needed for
     __float128.  */
#ifdef __i386__
  __float128 __max_align_f128 __attribute__((__aligned__(__alignof(__float128))));
#endif
} max_align_t;
#endif
#endif /* C11 or C++11.  */

#if defined(__cplusplus) && __cplusplus >= 201103L
#ifndef _GXX_NULLPTR_T
#define _GXX_NULLPTR_T
  typedef decltype(nullptr) nullptr_t;
#endif
#endif /* C++11.  */

#if (defined (__STDC_VERSION__) && __STDC_VERSION__ > 201710L)
#ifndef _GCC_NULLPTR_T
#define _GCC_NULLPTR_T
  typedef __typeof__(nullptr) nullptr_t;
/* ??? This doesn't define __STDC_VERSION_STDDEF_H__ yet.  */
#endif
#endif /* C23.  */

#if defined __STDC_VERSION__ && __STDC_VERSION__ > 201710L
#define unreachable() (__builtin_unreachable ())
#endif

#endif /* _STDDEF_H was defined this time */

#endif /* !_STDDEF_H && !_STDDEF_H_ && !_ANSI_STDDEF_H && !__STDDEF_H__
	  || __need_XXX was not defined before */