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. It ignores
  18  * its header guard so that multiple submodules can export its interfaces.
  19  * Take module SM with submodules A and B, whose headers both include stddef.h
  20  * When SM.A builds, __STDDEF_H will be defined. When SM.B builds, the
  21  * definition from SM.A will leak when building without local submodule
  22  * visibility. stddef.h wouldn't include any of its implementation headers, and
  23  * SM.B wouldn't import any of the stddef modules, and SM.B's `export *`
  24  * wouldn't export any stddef interfaces as expected. However, since stddef.h
  25  * ignores its header guard when building with modules, it all works as
  26  * expected.
  27  *
  28  * When clang modules are not enabled, the header guards can function in the
  29  * normal simple fashion.
  30  */
  31 #if !defined(__STDDEF_H) || __has_feature(modules) ||                          \
  32     (defined(__STDC_WANT_LIB_EXT1__) && __STDC_WANT_LIB_EXT1__ >= 1) ||        \
  33     defined(__need_ptrdiff_t) || defined(__need_size_t) ||                     \
  34     defined(__need_rsize_t) || defined(__need_wchar_t) ||                      \
  35     defined(__need_NULL) || defined(__need_nullptr_t) ||                       \
  36     defined(__need_unreachable) || defined(__need_max_align_t) ||              \
  37     defined(__need_offsetof) || defined(__need_wint_t)
  38
  39 #if !defined(__need_ptrdiff_t) && !defined(__need_size_t) &&                   \
  40     !defined(__need_rsize_t) && !defined(__need_wchar_t) &&                    \
  41     !defined(__need_NULL) && !defined(__need_nullptr_t) &&                     \
  42     !defined(__need_unreachable) && !defined(__need_max_align_t) &&            \
  43     !defined(__need_offsetof) && !defined(__need_wint_t)
  44 #define __STDDEF_H
  45 #define __need_ptrdiff_t
  46 #define __need_size_t
  47 /* ISO9899:2011 7.20 (C11 Annex K): Define rsize_t if __STDC_WANT_LIB_EXT1__ is
  48  * enabled. */
  49 #if defined(__STDC_WANT_LIB_EXT1__) && __STDC_WANT_LIB_EXT1__ >= 1
  50 #define __need_rsize_t
  51 #endif
  52 #define __need_wchar_t
  53 #define __need_NULL
  54 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) ||              \
  55     defined(__cplusplus)
  56 #define __need_nullptr_t
  57 #endif
  58 #if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
  59 #define __need_unreachable
  60 #endif
  61 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) ||              \
  62     (defined(__cplusplus) && __cplusplus >= 201103L)
  63 #define __need_max_align_t
  64 #endif
  65 #define __need_offsetof
  66 /* wint_t is provided by <wchar.h> and not <stddef.h>. It's here
  67  * for compatibility, but must be explicitly requested. Therefore
  68  * __need_wint_t is intentionally not defined here. */
  69 #endif
  70
  71 #if defined(__need_ptrdiff_t)
  72 #include <__stddef_ptrdiff_t.h>
  73 #undef __need_ptrdiff_t
  74 #endif /* defined(__need_ptrdiff_t) */
  75
  76 #if defined(__need_size_t)
  77 #include <__stddef_size_t.h>
  78 #undef __need_size_t
  79 #endif /*defined(__need_size_t) */
  80
  81 #if defined(__need_rsize_t)
  82 #include <__stddef_rsize_t.h>
  83 #undef __need_rsize_t
  84 #endif /* defined(__need_rsize_t) */
  85
  86 #if defined(__need_wchar_t)
  87 #include <__stddef_wchar_t.h>
  88 #undef __need_wchar_t
  89 #endif /* defined(__need_wchar_t) */
  90
  91 #if defined(__need_NULL)
  92 #include <__stddef_null.h>
  93 #undef __need_NULL
  94 #endif /* defined(__need_NULL) */
  95
  96 #if defined(__need_nullptr_t)
  97 #include <__stddef_nullptr_t.h>
  98 #undef __need_nullptr_t
  99 #endif /* defined(__need_nullptr_t) */
 100
 101 #if defined(__need_unreachable)
 102 #include <__stddef_unreachable.h>
 103 #undef __need_unreachable
 104 #endif /* defined(__need_unreachable) */
 105
 106 #if defined(__need_max_align_t)
 107 #include <__stddef_max_align_t.h>
 108 #undef __need_max_align_t
 109 #endif /* defined(__need_max_align_t) */
 110
 111 #if defined(__need_offsetof)
 112 #include <__stddef_offsetof.h>
 113 #undef __need_offsetof
 114 #endif /* defined(__need_offsetof) */
 115
 116 /* Some C libraries expect to see a wint_t here. Others (notably MinGW) will use
 117 __WINT_TYPE__ directly; accommodate both by requiring __need_wint_t */
 118 #if defined(__need_wint_t)
 119 #include <__stddef_wint_t.h>
 120 #undef __need_wint_t
 121 #endif /* __need_wint_t */
 122
 123 #endif