gl/stddef.in.h

   1 /* A substitute for POSIX 2008 <stddef.h>, for platforms that have issues.
   2
   3    Copyright (C) 2009-2023 Free Software Foundation, Inc.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file 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 Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser 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    /* On TinyCC, make sure that the macros that indicate the special invocation
  46       convention get undefined.  */
  47 #  undef __need_wchar_t
  48 #  undef __need_size_t
  49 #  undef __need_ptrdiff_t
  50 #  undef __need_NULL
  51 #  undef __need_wint_t
  52 # endif
  53
  54 #else
  55 /* Normal invocation convention.  */
  56
  57 # ifndef _@GUARD_PREFIX@_STDDEF_H
  58
  59 /* On AIX 7.2, with xlc in 64-bit mode, <stddef.h> defines max_align_t to a
  60    type with alignment 4, but 'long' has alignment 8.  */
  61 #  if defined _AIX && defined __LP64__
  62 #   if !GNULIB_defined_max_align_t
  63 #    ifdef _MAX_ALIGN_T
  64 /* /usr/include/stddef.h has already defined max_align_t.  Override it.  */
  65 typedef long rpl_max_align_t;
  66 #     define max_align_t rpl_max_align_t
  67 #    else
  68 /* Prevent /usr/include/stddef.h from defining max_align_t.  */
  69 typedef long max_align_t;
  70 #     define _MAX_ALIGN_T
  71 #    endif
  72 #    define GNULIB_defined_max_align_t 1
  73 #   endif
  74 #  endif
  75
  76 /* The include_next requires a split double-inclusion guard.  */
  77
  78 #  @INCLUDE_NEXT@ @NEXT_STDDEF_H@
  79
  80 /* On NetBSD 5.0, the definition of NULL lacks proper parentheses.  */
  81 #  if (@REPLACE_NULL@ \
  82        && (!defined _@GUARD_PREFIX@_STDDEF_H || defined _GL_STDDEF_WINT_T))
  83 #   undef NULL
  84 #   ifdef __cplusplus
  85    /* ISO C++ says that the macro NULL must expand to an integer constant
  86       expression, hence '((void *) 0)' is not allowed in C++.  */
  87 #    if __GNUG__ >= 3
  88     /* GNU C++ has a __null macro that behaves like an integer ('int' or
  89        'long') but has the same size as a pointer.  Use that, to avoid
  90        warnings.  */
  91 #     define NULL __null
  92 #    else
  93 #     define NULL 0L
  94 #    endif
  95 #   else
  96 #    define NULL ((void *) 0)
  97 #   endif
  98 #  endif
  99
 100 #  ifndef _@GUARD_PREFIX@_STDDEF_H
 101 #   define _@GUARD_PREFIX@_STDDEF_H
 102
 103 /* Some platforms lack wchar_t.  */
 104 #if !@HAVE_WCHAR_T@
 105 # define wchar_t int
 106 #endif
 107
 108 /* Some platforms lack max_align_t.  The check for _GCC_MAX_ALIGN_T is
 109    a hack in case the configure-time test was done with g++ even though
 110    we are currently compiling with gcc.
 111    On MSVC, max_align_t is defined only in C++ mode, after <cstddef> was
 112    included.  Its definition is good since it has an alignment of 8 (on x86
 113    and x86_64).
 114    Similarly on OS/2 kLIBC.  */
 115 #if (defined _MSC_VER || (defined __KLIBC__ && !defined __LIBCN__)) \
 116     && defined __cplusplus
 117 # include <cstddef>
 118 #else
 119 # if ! (@HAVE_MAX_ALIGN_T@ || (defined _GCC_MAX_ALIGN_T && !defined __clang__))
 120 #  if !GNULIB_defined_max_align_t
 121 /* On the x86, the maximum storage alignment of double, long, etc. is 4,
 122    but GCC's C11 ABI for x86 says that max_align_t has an alignment of 8,
 123    and the C11 standard allows this.  Work around this problem by
 124    using __alignof__ (which returns 8 for double) rather than _Alignof
 125    (which returns 4), and align each union member accordingly.  */
 126 #   if defined __GNUC__ || (__clang_major__ >= 4)
 127 #    define _GL_STDDEF_ALIGNAS(type) \
 128        __attribute__ ((__aligned__ (__alignof__ (type))))
 129 #   else
 130 #    define _GL_STDDEF_ALIGNAS(type) /* */
 131 #   endif
 132 typedef union
 133 {
 134   char *__p _GL_STDDEF_ALIGNAS (char *);
 135   double __d _GL_STDDEF_ALIGNAS (double);
 136   long double __ld _GL_STDDEF_ALIGNAS (long double);
 137   long int __i _GL_STDDEF_ALIGNAS (long int);
 138 } rpl_max_align_t;
 139 #   define max_align_t rpl_max_align_t
 140 #   define GNULIB_defined_max_align_t 1
 141 #  endif
 142 # endif
 143 #endif
 144
 145 #  endif /* _@GUARD_PREFIX@_STDDEF_H */
 146 # endif /* _@GUARD_PREFIX@_STDDEF_H */
 147 #endif /* __need_XXX */