clang/lib/Headers/stddef.h

   1 /*===---- stddef.h - Basic type definitions --------------------------------===
   2  *
   3  * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4  * See https://llvm.org/LICENSE.txt for license information.
   5  * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6  *
   7  *===-----------------------------------------------------------------------===
   8  */
   9
  10 /*
  11  * This header is designed to be included multiple times. If any of the __need_
  12  * macros are defined, then only that subset of interfaces are provided. This
  13  * can be useful for POSIX headers that need to not expose all of stddef.h, but
  14  * need to use some of its interfaces. Otherwise this header provides all of
  15  * the expected interfaces.
  16  *
  17  * When clang modules are enabled, this header is a textual header to support
  18  * the multiple include behavior. As such, it doesn't directly declare anything
  19  * so that it doesn't add duplicate declarations to all of its includers'
  20  * modules.
  21  */
  22 #if defined(__MVS__) && __has_include_next(<stddef.h>)
  23 #undef __need_ptrdiff_t
  24 #undef __need_size_t
  25 #undef __need_rsize_t
  26 #undef __need_wchar_t
  27 #undef __need_NULL
  28 #undef __need_nullptr_t
  29 #undef __need_unreachable
  30 #undef __need_max_align_t
  31 #undef __need_offsetof
  32 #undef __need_wint_t
  33 #include <__stddef_header_macro.h>
  34 #include_next <stddef.h>
  35
  36 #else
  37
  38 #if !defined(__need_ptrdiff_t) && !defined(__need_size_t) &&                   \
  39     !defined(__need_rsize_t) && !defined(__need_wchar_t) &&                    \
  40     !defined(__need_NULL) && !defined(__need_nullptr_t) &&                     \
  41     !defined(__need_unreachable) && !defined(__need_max_align_t) &&            \
  42     !defined(__need_offsetof) && !defined(__need_wint_t)
  43 #define __need_ptrdiff_t
  44 #define __need_size_t
  45 /* ISO9899:2011 7.20 (C11 Annex K): Define rsize_t if __STDC_WANT_LIB_EXT1__ is
  46  * enabled. */
  47 #if defined(__STDC_WANT_LIB_EXT1__) && __STDC_WANT_LIB_EXT1__ >= 1
  48 #define __need_rsize_t
  49 #endif
  50 #define __need_wchar_t
  51 #if !defined(__STDDEF_H) || __has_feature(modules)
  52 /*
  53  * __stddef_null.h is special when building without modules: if __need_NULL is
  54  * set, then it will unconditionally redefine NULL. To avoid stepping on client
  55  * definitions of NULL, __need_NULL should only be set the first time this
  56  * header is included, that is when __STDDEF_H is not defined. However, when
  57  * building with modules, this header is a textual header and needs to
  58  * unconditionally include __stdef_null.h to support multiple submodules
  59  * exporting _Builtin_stddef.null. Take module SM with submodules A and B, whose
  60  * headers both include stddef.h When SM.A builds, __STDDEF_H will be defined.
  61  * When SM.B builds, the definition from SM.A will leak when building without
  62  * local submodule visibility. stddef.h wouldn't include __stddef_null.h, and
  63  * SM.B wouldn't import _Builtin_stddef.null, and SM.B's `export *` wouldn't
  64  * export NULL as expected. When building with modules, always include
  65  * __stddef_null.h so that everything works as expected.
  66  */
  67 #define __need_NULL
  68 #endif
  69 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) ||              \
  70     defined(__cplusplus)
  71 #define __need_nullptr_t
  72 #endif
  73 #if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
  74 #define __need_unreachable
  75 #endif
  76 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) ||              \
  77     (defined(__cplusplus) && __cplusplus >= 201103L)
  78 #define __need_max_align_t
  79 #endif
  80 #define __need_offsetof
  81 /* wint_t is provided by <wchar.h> and not <stddef.h>. It's here
  82  * for compatibility, but must be explicitly requested. Therefore
  83  * __need_wint_t is intentionally not defined here. */
  84 #include <__stddef_header_macro.h>
  85 #endif
  86
  87 #if defined(__need_ptrdiff_t)
  88 #include <__stddef_ptrdiff_t.h>
  89 #undef __need_ptrdiff_t
  90 #endif /* defined(__need_ptrdiff_t) */
  91
  92 #if defined(__need_size_t)
  93 #include <__stddef_size_t.h>
  94 #undef __need_size_t
  95 #endif /*defined(__need_size_t) */
  96
  97 #if defined(__need_rsize_t)
  98 #include <__stddef_rsize_t.h>
  99 #undef __need_rsize_t
 100 #endif /* defined(__need_rsize_t) */
 101
 102 #if defined(__need_wchar_t)
 103 #include <__stddef_wchar_t.h>
 104 #undef __need_wchar_t
 105 #endif /* defined(__need_wchar_t) */
 106
 107 #if defined(__need_NULL)
 108 #include <__stddef_null.h>
 109 #undef __need_NULL
 110 #endif /* defined(__need_NULL) */
 111
 112 #if defined(__need_nullptr_t)
 113 #include <__stddef_nullptr_t.h>
 114 #undef __need_nullptr_t
 115 #endif /* defined(__need_nullptr_t) */
 116
 117 #if defined(__need_unreachable)
 118 #include <__stddef_unreachable.h>
 119 #undef __need_unreachable
 120 #endif /* defined(__need_unreachable) */
 121
 122 #if defined(__need_max_align_t)
 123 #include <__stddef_max_align_t.h>
 124 #undef __need_max_align_t
 125 #endif /* defined(__need_max_align_t) */
 126
 127 #if defined(__need_offsetof)
 128 #include <__stddef_offsetof.h>
 129 #undef __need_offsetof
 130 #endif /* defined(__need_offsetof) */
 131
 132 /* Some C libraries expect to see a wint_t here. Others (notably MinGW) will use
 133 __WINT_TYPE__ directly; accommodate both by requiring __need_wint_t */
 134 #if defined(__need_wint_t)
 135 #include <__stddef_wint_t.h>
 136 #undef __need_wint_t
 137 #endif /* __need_wint_t */
 138
 139 #endif /* __MVS__ */