lib/stddef.in.h

   1 /* A substitute for POSIX 2008 <stddef.h>, for platforms that have issues.
   2
   3    Copyright (C) 2009-2020 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Eric Blake.  */
  19
  20 /*
  21  * POSIX 2008 <stddef.h> for platforms that have issues.
  22  * <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stddef.h.html>
  23  */
  24
  25 #if __GNUC__ >= 3
  26 @PRAGMA_SYSTEM_HEADER@
  27 #endif
  28 @PRAGMA_COLUMNS@
  29
  30 #if defined __need_wchar_t || defined __need_size_t  \
  31   || defined __need_ptrdiff_t || defined __need_NULL \
  32   || defined __need_wint_t
  33 /* Special invocation convention inside gcc header files.  In
  34    particular, gcc provides a version of <stddef.h> that blindly
  35    redefines NULL even when __need_wint_t was defined, even though
  36    wint_t is not normally provided by <stddef.h>.  Hence, we must
  37    remember if special invocation has ever been used to obtain wint_t,
  38    in which case we need to clean up NULL yet again.  */
  39
  40 # if !(defined _@GUARD_PREFIX@_STDDEF_H && defined _GL_STDDEF_WINT_T)
  41 #  ifdef __need_wint_t
  42 #   define _GL_STDDEF_WINT_T
  43 #  endif
  44 #  @INCLUDE_NEXT@ @NEXT_STDDEF_H@
  45 # endif
  46
  47 #else
  48 /* Normal invocation convention.  */
  49
  50 # ifndef _@GUARD_PREFIX@_STDDEF_H
  51
  52 /* The include_next requires a split double-inclusion guard.  */
  53
  54 #  @INCLUDE_NEXT@ @NEXT_STDDEF_H@
  55
  56 /* On NetBSD 5.0, the definition of NULL lacks proper parentheses.  */
  57 #  if (@REPLACE_NULL@ \
  58        && (!defined _@GUARD_PREFIX@_STDDEF_H || defined _GL_STDDEF_WINT_T))
  59 #   undef NULL
  60 #   ifdef __cplusplus
  61    /* ISO C++ says that the macro NULL must expand to an integer constant
  62       expression, hence '((void *) 0)' is not allowed in C++.  */
  63 #    if __GNUG__ >= 3
  64     /* GNU C++ has a __null macro that behaves like an integer ('int' or
  65        'long') but has the same size as a pointer.  Use that, to avoid
  66        warnings.  */
  67 #     define NULL __null
  68 #    else
  69 #     define NULL 0L
  70 #    endif
  71 #   else
  72 #    define NULL ((void *) 0)
  73 #   endif
  74 #  endif
  75
  76 #  ifndef _@GUARD_PREFIX@_STDDEF_H
  77 #   define _@GUARD_PREFIX@_STDDEF_H
  78
  79 /* Some platforms lack wchar_t.  */
  80 #if !@HAVE_WCHAR_T@
  81 # define wchar_t int
  82 #endif
  83
  84 /* Some platforms lack max_align_t.  The check for _GCC_MAX_ALIGN_T is
  85    a hack in case the configure-time test was done with g++ even though
  86    we are currently compiling with gcc.
  87    On MSVC, max_align_t is defined only in C++ mode, after <cstddef> was
  88    included.  Its definition is good since it has an alignment of 8 (on x86
  89    and x86_64).  */
  90 #if defined _MSC_VER && defined __cplusplus
  91 # include <cstddef>
  92 #else
  93 # if ! (@HAVE_MAX_ALIGN_T@ || defined _GCC_MAX_ALIGN_T)
  94 #  if !GNULIB_defined_max_align_t
  95 /* On the x86, the maximum storage alignment of double, long, etc. is 4,
  96    but GCC's C11 ABI for x86 says that max_align_t has an alignment of 8,
  97    and the C11 standard allows this.  Work around this problem by
  98    using __alignof__ (which returns 8 for double) rather than _Alignof
  99    (which returns 4), and align each union member accordingly.  */
 100 #   if defined __GNUC__ || (__clang_major__ >= 4)
 101 #    define _GL_STDDEF_ALIGNAS(type) \
 102        __attribute__ ((__aligned__ (__alignof__ (type))))
 103 #   else
 104 #    define _GL_STDDEF_ALIGNAS(type) /* */
 105 #   endif
 106 typedef union
 107 {
 108   char *__p _GL_STDDEF_ALIGNAS (char *);
 109   double __d _GL_STDDEF_ALIGNAS (double);
 110   long double __ld _GL_STDDEF_ALIGNAS (long double);
 111   long int __i _GL_STDDEF_ALIGNAS (long int);
 112 } rpl_max_align_t;
 113 #   define max_align_t rpl_max_align_t
 114 #   define GNULIB_defined_max_align_t 1
 115 #  endif
 116 # endif
 117 #endif
 118
 119 #  endif /* _@GUARD_PREFIX@_STDDEF_H */
 120 # endif /* _@GUARD_PREFIX@_STDDEF_H */
 121 #endif /* __need_XXX */