73 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++17, c++2010 11// constexpr void swap(unexpected& other) noexcept(is_nothrow_swappable_v<E>);12//13// Mandates: is_swappable_v<E> is true.14//15// Effects: Equivalent to: using std::swap; swap(unex, other.unex);16 17#include <cassert>18#include <concepts>19#include <expected>20#include <utility>21 22// test noexcept23struct NoexceptSwap {24 friend void swap(NoexceptSwap&, NoexceptSwap&) noexcept;25};26 27struct MayThrowSwap {28 friend void swap(MayThrowSwap&, MayThrowSwap&);29};30 31template <class T>32concept MemberSwapNoexcept =33 requires(T& t1, T& t2) {34 { t1.swap(t2) } noexcept;35 };36 37static_assert(MemberSwapNoexcept<std::unexpected<NoexceptSwap>>);38static_assert(!MemberSwapNoexcept<std::unexpected<MayThrowSwap>>);39 40struct ADLSwap {41 constexpr ADLSwap(int ii) : i(ii) {}42 ADLSwap& operator=(const ADLSwap&) = delete;43 int i;44 constexpr friend void swap(ADLSwap& x, ADLSwap& y) { std::swap(x.i, y.i); }45};46 47constexpr bool test() {48 // using std::swap;49 {50 std::unexpected<int> unex1(5);51 std::unexpected<int> unex2(6);52 unex1.swap(unex2);53 assert(unex1.error() == 6);54 assert(unex2.error() == 5);55 }56 57 // adl swap58 {59 std::unexpected<ADLSwap> unex1(5);60 std::unexpected<ADLSwap> unex2(6);61 unex1.swap(unex2);62 assert(unex1.error().i == 6);63 assert(unex2.error().i == 5);64 }65 return true;66}67 68int main(int, char**) {69 test();70 static_assert(test());71 return 0;72}73