947dfc95ca
Reviewed By: Mordante, #libc Spies: libcxx-commits Differential Revision: https://reviews.llvm.org/D140426
70 lines
1.8 KiB
C++
70 lines
1.8 KiB
C++
//===----------------------------------------------------------------------===//
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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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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
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// friend constexpr void swap(unexpected& x, unexpected& y) noexcept(noexcept(x.swap(y)));
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//
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// Constraints: is_swappable_v<E> is true.
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//
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// Effects: Equivalent to x.swap(y).
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#include <cassert>
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#include <concepts>
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#include <expected>
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#include <type_traits>
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#include <utility>
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// test noexcept
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struct NoexceptSwap {
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friend void swap(NoexceptSwap&, NoexceptSwap&) noexcept;
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};
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struct MayThrowSwap {
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friend void swap(MayThrowSwap&, MayThrowSwap&);
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};
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template <class T>
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concept ADLSwapNoexcept =
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requires(T& t1, T& t2) {
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{ swap(t1, t2) } noexcept;
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};
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static_assert(ADLSwapNoexcept<std::unexpected<NoexceptSwap>>);
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static_assert(!ADLSwapNoexcept<std::unexpected<MayThrowSwap>>);
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// test constraint
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struct NonSwappable {
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NonSwappable& operator=(const NonSwappable&) = delete;
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};
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static_assert(std::is_swappable_v<std::unexpected<int>>);
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static_assert(std::is_swappable_v<std::unexpected<MayThrowSwap>>);
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static_assert(!std::is_swappable_v<std::unexpected<NonSwappable>>);
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struct ADLSwap {
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constexpr ADLSwap(int ii) : i(ii) {}
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ADLSwap& operator=(const ADLSwap&) = delete;
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int i;
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constexpr friend void swap(ADLSwap& x, ADLSwap& y) { std::swap(x.i, y.i); }
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};
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constexpr bool test() {
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std::unexpected<ADLSwap> unex1(5);
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std::unexpected<ADLSwap> unex2(6);
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swap(unex1, unex2);
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assert(unex1.error().i == 6);
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assert(unex2.error().i == 5);
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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