Nikolas Klauser e78f53d1e8
Reapply "[libc++][C++03] Copy the LLVM 19 headers (#108999)" (#112127)
This reverts commit 68c04b0ae62d8431d72d8b47fc13008002ee4387.

This disables the IWYU mapping that caused the failure, since
the headers aren't reachable for now.

This is the first part of the "Freezing C++03 headers" proposal
explained in
https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319/58.

This patch mechanically copies the headers as of the LLVM 19.1 release
into a subdirectory of libc++ so that we can start using these headers
when building in C++03 mode. We are going to be backporting important
changes to that copy of the headers until the LLVM 21 release. After the
LLVM 21 release, only critical bugfixes will be fixed in the C++03 copy
of the headers.

This patch only performs a copy of the headers -- these headers are
still unused by the rest of the codebase.
2024-10-24 00:17:37 +02:00

45 lines
1.3 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___BIT_BIT_CAST_H
#define _LIBCPP___BIT_BIT_CAST_H
#include <__config>
#include <__type_traits/is_trivially_copyable.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#ifndef _LIBCPP_CXX03_LANG
template <class _ToType, class _FromType>
_LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI constexpr _ToType __bit_cast(const _FromType& __from) noexcept {
return __builtin_bit_cast(_ToType, __from);
}
#endif // _LIBCPP_CXX03_LANG
#if _LIBCPP_STD_VER >= 20
template <class _ToType, class _FromType>
requires(sizeof(_ToType) == sizeof(_FromType) && is_trivially_copyable_v<_ToType> &&
is_trivially_copyable_v<_FromType>)
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _ToType bit_cast(const _FromType& __from) noexcept {
return __builtin_bit_cast(_ToType, __from);
}
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___BIT_BIT_CAST_H