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
23struct 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(a&: x.i, b&: 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 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
68int main(int, char**) {
69 test();
70 static_assert(test());
71 return 0;
72}
73

source code of libcxx/test/std/utilities/expected/expected.unexpected/swap/swap.member.pass.cpp