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a5b3d3a03f
The current implementation of `{std, ranges}::copy` fails to copy
`vector<bool>` correctly when the underlying storage type
(`__storage_type`) is smaller than `int`, such as `unsigned char`,
`unsigned short`, `uint8_t` and `uint16_t`. The root cause is that the
unsigned small storage type undergoes integer promotion to (signed)
`int`, which is then left and right shifted, leading to UB (before
C++20) and sign-bit extension (since C++20) respectively. As a result,
the underlying bit mask evaluations become incorrect, causing erroneous
copying behavior.
This patch resolves the issue by correcting the internal bitwise
operations, ensuring that `{std, ranges}::copy` operates correctly for
`vector<bool>` with any custom (unsigned) storage types.
Fixes #131692.
45 lines
1.4 KiB
C++
45 lines
1.4 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___FWD_BIT_REFERENCE_H
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#define _LIBCPP___FWD_BIT_REFERENCE_H
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#include <__config>
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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_BEGIN_NAMESPACE_STD
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template <class _Cp, bool _IsConst, typename _Cp::__storage_type = 0>
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class __bit_iterator;
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template <class _Cp>
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struct __bit_array;
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template <class, class = void>
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struct __size_difference_type_traits;
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template <class _StoragePointer>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
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__fill_masked_range(_StoragePointer __word, unsigned __clz, unsigned __ctz, bool __fill_val);
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template <class _StorageType>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __trailing_mask(unsigned __clz);
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template <class _StorageType>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __leading_mask(unsigned __ctz);
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template <class _StorageType>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __middle_mask(unsigned __clz, unsigned __ctz);
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___FWD_BIT_REFERENCE_H
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