1//===----------------------------------------------------------------------===//
2// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
3// See https://llvm.org/LICENSE.txt for license information.
4// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
5//
6//===----------------------------------------------------------------------===//
7
8// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
9
10// friend constexpr void swap(unexpected& x, unexpected& y) noexcept(noexcept(x.swap(y)));
11//
12// Constraints: is_swappable_v<E> is true.
13//
14// Effects: Equivalent to x.swap(y).
15
16#include <cassert>
17#include <concepts>
18#include <expected>
19#include <type_traits>
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 ADLSwapNoexcept =
33 requires(T& t1, T& t2) {
34 { swap(t1, t2) } noexcept;
35 };
36
37static_assert(ADLSwapNoexcept<std::unexpected<NoexceptSwap>>);
38static_assert(!ADLSwapNoexcept<std::unexpected<MayThrowSwap>>);
39
40// test constraint
41struct NonSwappable {
42 NonSwappable& operator=(const NonSwappable&) = delete;
43};
44
45static_assert(std::is_swappable_v<std::unexpected<int>>);
46static_assert(std::is_swappable_v<std::unexpected<MayThrowSwap>>);
47static_assert(!std::is_swappable_v<std::unexpected<NonSwappable>>);
48
49struct ADLSwap {
50 constexpr ADLSwap(int ii) : i(ii) {}
51 ADLSwap& operator=(const ADLSwap&) = delete;
52 int i;
53 constexpr friend void swap(ADLSwap& x, ADLSwap& y) { std::swap(a&: x.i, b&: y.i); }
54};
55
56constexpr bool test() {
57 std::unexpected<ADLSwap> unex1(5);
58 std::unexpected<ADLSwap> unex2(6);
59 swap(unex1, unex2);
60 assert(unex1.error().i == 6);
61 assert(unex2.error().i == 5);
62 return true;
63}
64
65int main(int, char**) {
66 test();
67 static_assert(test());
68 return 0;
69}
70

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