92a9d4831d
stddef.h always includes __stddef_null.h. This is fine in modules because it's not possible to re-include the pcm, and it's necessary to export the _Builtin_stddef.null submodule. However, without modules it causes NULL to always get redefined which disrupts some C++ code. Rework the inclusion of __stddef_null.h so that with not building with modules it's only included if __need_NULL is set by the includer, or it's the first time stddef.h is being included.
140 lines
4.9 KiB
C++
140 lines
4.9 KiB
C++
/*===---- stddef.h - Basic type definitions --------------------------------===
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*
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* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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* See https://llvm.org/LICENSE.txt for license information.
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* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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*
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*===-----------------------------------------------------------------------===
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*/
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/*
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* This header is designed to be included multiple times. If any of the __need_
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* macros are defined, then only that subset of interfaces are provided. This
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* can be useful for POSIX headers that need to not expose all of stddef.h, but
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* need to use some of its interfaces. Otherwise this header provides all of
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* the expected interfaces.
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*
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* When clang modules are enabled, this header is a textual header to support
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* the multiple include behavior. As such, it doesn't directly declare anything
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* so that it doesn't add duplicate declarations to all of its includers'
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* modules.
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*/
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#if defined(__MVS__) && __has_include_next(<stddef.h>)
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#undef __need_ptrdiff_t
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#undef __need_size_t
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#undef __need_rsize_t
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#undef __need_wchar_t
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#undef __need_NULL
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#undef __need_nullptr_t
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#undef __need_unreachable
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#undef __need_max_align_t
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#undef __need_offsetof
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#undef __need_wint_t
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#include <__stddef_header_macro.h>
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#include_next <stddef.h>
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#else
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#if !defined(__need_ptrdiff_t) && !defined(__need_size_t) && \
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!defined(__need_rsize_t) && !defined(__need_wchar_t) && \
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!defined(__need_NULL) && !defined(__need_nullptr_t) && \
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!defined(__need_unreachable) && !defined(__need_max_align_t) && \
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!defined(__need_offsetof) && !defined(__need_wint_t)
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#define __need_ptrdiff_t
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#define __need_size_t
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/* ISO9899:2011 7.20 (C11 Annex K): Define rsize_t if __STDC_WANT_LIB_EXT1__ is
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* enabled. */
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#if defined(__STDC_WANT_LIB_EXT1__) && __STDC_WANT_LIB_EXT1__ >= 1
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#define __need_rsize_t
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#endif
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#define __need_wchar_t
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#if !defined(__STDDEF_H) || __has_feature(modules)
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/*
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* __stddef_null.h is special when building without modules: if __need_NULL is
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* set, then it will unconditionally redefine NULL. To avoid stepping on client
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* definitions of NULL, __need_NULL should only be set the first time this
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* header is included, that is when __STDDEF_H is not defined. However, when
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* building with modules, this header is a textual header and needs to
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* unconditionally include __stdef_null.h to support multiple submodules
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* exporting _Builtin_stddef.null. Take module SM with submodules A and B, whose
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* headers both include stddef.h When SM.A builds, __STDDEF_H will be defined.
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* When SM.B builds, the definition from SM.A will leak when building without
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* local submodule visibility. stddef.h wouldn't include __stddef_null.h, and
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* SM.B wouldn't import _Builtin_stddef.null, and SM.B's `export *` wouldn't
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* export NULL as expected. When building with modules, always include
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* __stddef_null.h so that everything works as expected.
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*/
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#define __need_NULL
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#endif
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#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || \
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defined(__cplusplus)
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#define __need_nullptr_t
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#endif
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#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
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#define __need_unreachable
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#endif
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#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) || \
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(defined(__cplusplus) && __cplusplus >= 201103L)
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#define __need_max_align_t
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#endif
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#define __need_offsetof
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/* wint_t is provided by <wchar.h> and not <stddef.h>. It's here
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* for compatibility, but must be explicitly requested. Therefore
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* __need_wint_t is intentionally not defined here. */
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#include <__stddef_header_macro.h>
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#endif
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#if defined(__need_ptrdiff_t)
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#include <__stddef_ptrdiff_t.h>
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#undef __need_ptrdiff_t
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#endif /* defined(__need_ptrdiff_t) */
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#if defined(__need_size_t)
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#include <__stddef_size_t.h>
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#undef __need_size_t
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#endif /*defined(__need_size_t) */
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#if defined(__need_rsize_t)
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#include <__stddef_rsize_t.h>
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#undef __need_rsize_t
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#endif /* defined(__need_rsize_t) */
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#if defined(__need_wchar_t)
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#include <__stddef_wchar_t.h>
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#undef __need_wchar_t
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#endif /* defined(__need_wchar_t) */
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#if defined(__need_NULL)
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#include <__stddef_null.h>
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#undef __need_NULL
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#endif /* defined(__need_NULL) */
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#if defined(__need_nullptr_t)
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#include <__stddef_nullptr_t.h>
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#undef __need_nullptr_t
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#endif /* defined(__need_nullptr_t) */
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#if defined(__need_unreachable)
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#include <__stddef_unreachable.h>
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#undef __need_unreachable
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#endif /* defined(__need_unreachable) */
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#if defined(__need_max_align_t)
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#include <__stddef_max_align_t.h>
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#undef __need_max_align_t
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#endif /* defined(__need_max_align_t) */
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#if defined(__need_offsetof)
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#include <__stddef_offsetof.h>
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#undef __need_offsetof
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#endif /* defined(__need_offsetof) */
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/* Some C libraries expect to see a wint_t here. Others (notably MinGW) will use
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__WINT_TYPE__ directly; accommodate both by requiring __need_wint_t */
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#if defined(__need_wint_t)
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#include <__stddef_wint_t.h>
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#undef __need_wint_t
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#endif /* __need_wint_t */
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#endif /* __MVS__ */
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