e78f53d1e8
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.
106 lines
2.8 KiB
C++
106 lines
2.8 KiB
C++
//===----------------------------------------------------------------------===//
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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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#ifndef _LIBCPP___ALGORITHM_SHIFT_RIGHT_H
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#define _LIBCPP___ALGORITHM_SHIFT_RIGHT_H
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#include <__algorithm/move.h>
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#include <__algorithm/move_backward.h>
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#include <__algorithm/swap_ranges.h>
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#include <__config>
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#include <__iterator/iterator_traits.h>
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#include <__utility/swap.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 20
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template <class _ForwardIterator>
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inline _LIBCPP_HIDE_FROM_ABI constexpr _ForwardIterator
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shift_right(_ForwardIterator __first,
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_ForwardIterator __last,
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typename iterator_traits<_ForwardIterator>::difference_type __n) {
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if (__n == 0) {
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return __first;
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}
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if constexpr (__has_random_access_iterator_category<_ForwardIterator>::value) {
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decltype(__n) __d = __last - __first;
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if (__n >= __d) {
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return __last;
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}
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_ForwardIterator __m = __first + (__d - __n);
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return std::move_backward(__first, __m, __last);
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} else if constexpr (__has_bidirectional_iterator_category<_ForwardIterator>::value) {
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_ForwardIterator __m = __last;
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for (; __n > 0; --__n) {
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if (__m == __first) {
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return __last;
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}
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--__m;
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}
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return std::move_backward(__first, __m, __last);
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} else {
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_ForwardIterator __ret = __first;
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for (; __n > 0; --__n) {
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if (__ret == __last) {
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return __last;
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}
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++__ret;
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}
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// We have an __n-element scratch space from __first to __ret.
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// Slide an __n-element window [__trail, __lead) from left to right.
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// We're essentially doing swap_ranges(__first, __ret, __trail, __lead)
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// over and over; but once __lead reaches __last we needn't bother
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// to save the values of elements [__trail, __last).
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auto __trail = __first;
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auto __lead = __ret;
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while (__trail != __ret) {
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if (__lead == __last) {
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std::move(__first, __trail, __ret);
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return __ret;
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}
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++__trail;
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++__lead;
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}
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_ForwardIterator __mid = __first;
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while (true) {
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if (__lead == __last) {
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__trail = std::move(__mid, __ret, __trail);
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std::move(__first, __mid, __trail);
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return __ret;
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}
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swap(*__mid, *__trail);
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++__mid;
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++__trail;
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++__lead;
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if (__mid == __ret) {
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__mid = __first;
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}
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}
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}
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}
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___ALGORITHM_SHIFT_RIGHT_H
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