xref: /freebsd/contrib/llvm-project/clang/lib/Headers/stddef.h (revision c57c26179033f64c2011a2d2a904ee3fa62e826a)
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
124