Louis Dionne d6832a611a
[libc++][modules] Modularize <cstddef> (#107254)
Many headers include `<cstddef>` just for size_t, and pulling in
additional content (e.g. the traits used for std::byte) is unnecessary.
To solve this problem, this patch splits up `<cstddef>` into
subcomponents so that headers can include only the parts that they
actually require.

This has the added benefit of making the modules build a lot stricter
with respect to IWYU, and also providing a canonical location where we
define `std::size_t` and friends (which were previously defined in
multiple headers like `<cstddef>` and `<ctime>`).

After this patch, there's still many places in the codebase where we
include `<cstddef>` when `<__cstddef/size_t.h>` would be sufficient.
This patch focuses on removing `<cstddef>` includes from __type_traits
to make these headers non-circular with `<cstddef>`. Additional
refactorings can be tackled separately.
2024-09-05 08:28:33 -04:00

60 lines
1.4 KiB
C++

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP_CSTDDEF
#define _LIBCPP_CSTDDEF
/*
cstddef synopsis
Macros:
offsetof(type,member-designator)
NULL
namespace std
{
Types:
ptrdiff_t
size_t
max_align_t // C++11
nullptr_t
byte // C++17
} // std
*/
#include <__config>
#include <version>
#include <stddef.h>
#ifndef _LIBCPP_STDDEF_H
# error <cstddef> tried including <stddef.h> but didn't find libc++'s <stddef.h> header. \
This usually means that your header search paths are not configured properly. \
The header search paths should contain the C++ Standard Library headers before \
any C Standard Library, and you are probably using compiler flags that make that \
not be the case.
#endif
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
#include <__cstddef/byte.h>
#include <__cstddef/max_align_t.h>
#include <__cstddef/nullptr_t.h>
#include <__cstddef/ptrdiff_t.h>
#include <__cstddef/size_t.h>
#endif // _LIBCPP_CSTDDEF