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

46 lines
1.5 KiB
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___FWD_PAIR_H
#define _LIBCPP___FWD_PAIR_H
#include <__config>
#include <__cstddef/size_t.h>
#include <__fwd/tuple.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
template <class, class>
struct _LIBCPP_TEMPLATE_VIS pair;
template <size_t _Ip, class _T1, class _T2>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, pair<_T1, _T2> >::type&
get(pair<_T1, _T2>&) _NOEXCEPT;
template <size_t _Ip, class _T1, class _T2>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
get(const pair<_T1, _T2>&) _NOEXCEPT;
#ifndef _LIBCPP_CXX03_LANG
template <size_t _Ip, class _T1, class _T2>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
get(pair<_T1, _T2>&&) _NOEXCEPT;
template <size_t _Ip, class _T1, class _T2>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
get(const pair<_T1, _T2>&&) _NOEXCEPT;
#endif
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___FWD_PAIR_H