1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
|
//===----------------------------------------------------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
// friend constexpr void swap(unexpected& x, unexpected& y) noexcept(noexcept(x.swap(y)));
//
// Constraints: is_swappable_v<E> is true.
//
// Effects: Equivalent to x.swap(y).
#include <cassert>
#include <concepts>
#include <expected>
#include <type_traits>
#include <utility>
// test noexcept
struct NoexceptSwap {
friend void swap(NoexceptSwap&, NoexceptSwap&) noexcept;
};
struct MayThrowSwap {
friend void swap(MayThrowSwap&, MayThrowSwap&);
};
template <class T>
concept ADLSwapNoexcept =
requires(T& t1, T& t2) {
{ swap(t1, t2) } noexcept;
};
static_assert(ADLSwapNoexcept<std::unexpected<NoexceptSwap>>);
static_assert(!ADLSwapNoexcept<std::unexpected<MayThrowSwap>>);
// test constraint
struct NonSwappable {
NonSwappable& operator=(const NonSwappable&) = delete;
};
static_assert(std::is_swappable_v<std::unexpected<int>>);
static_assert(std::is_swappable_v<std::unexpected<MayThrowSwap>>);
static_assert(!std::is_swappable_v<std::unexpected<NonSwappable>>);
struct ADLSwap {
constexpr ADLSwap(int ii) : i(ii) {}
ADLSwap& operator=(const ADLSwap&) = delete;
int i;
constexpr friend void swap(ADLSwap& x, ADLSwap& y) { std::swap(x.i, y.i); }
};
constexpr bool test() {
std::unexpected<ADLSwap> unex1(5);
std::unexpected<ADLSwap> unex2(6);
swap(unex1, unex2);
assert(unex1.error().i == 6);
assert(unex2.error().i == 5);
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
|
