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-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20 10 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 noexcept 23 struct NoexceptSwap { 24 friend void swap(NoexceptSwap&, NoexceptSwap&) noexcept; 25 }; 26 27 struct MayThrowSwap { 28 friend void swap(MayThrowSwap&, MayThrowSwap&); 29 }; 30 31 template <class T> 32 concept MemberSwapNoexcept = 33 requires(T& t1, T& t2) { 34 { t1.swap(t2) } noexcept; 35 }; 36 37 static_assert(MemberSwapNoexcept<std::unexpected<NoexceptSwap>>); 38 static_assert(!MemberSwapNoexcept<std::unexpected<MayThrowSwap>>); 39 40 struct 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 47 constexpr 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 swap 58 { 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 68 int main(int, char**) { 69 test(); 70 static_assert(test()); 71 return 0; 72 } 73