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
70
71
72
|
//===----------------------------------------------------------------------===//
//
// 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
// <optional>
// template<class F> constexpr optional or_else(F&&) &&;
// template<class F> constexpr optional or_else(F&&) const&;
#include "MoveOnly.h"
#include <cassert>
#include <optional>
struct NonMovable {
NonMovable() = default;
NonMovable(NonMovable&&) = delete;
};
template <class Opt, class F>
concept has_or_else = requires(Opt&& opt, F&& f) {
{std::forward<Opt>(opt).or_else(std::forward<F>(f))};
};
template <class T>
std::optional<T> return_optional() {}
static_assert(has_or_else<std::optional<int>&, decltype(return_optional<int>)>);
static_assert(has_or_else<std::optional<int>&&, decltype(return_optional<int>)>);
static_assert(!has_or_else<std::optional<MoveOnly>&, decltype(return_optional<MoveOnly>)>);
static_assert(has_or_else<std::optional<MoveOnly>&&, decltype(return_optional<MoveOnly>)>);
static_assert(!has_or_else<std::optional<NonMovable>&, decltype(return_optional<NonMovable>)>);
static_assert(!has_or_else<std::optional<NonMovable>&&, decltype(return_optional<NonMovable>)>);
std::optional<int> take_int(int) { return 0; }
void take_int_return_void(int) {}
static_assert(!has_or_else<std::optional<int>, decltype(take_int)>);
static_assert(!has_or_else<std::optional<int>, decltype(take_int_return_void)>);
static_assert(!has_or_else<std::optional<int>, int>);
constexpr bool test() {
{
std::optional<int> opt;
assert(opt.or_else([] { return std::optional<int>{0}; }) == 0);
opt = 1;
opt.or_else([] {
assert(false);
return std::optional<int>{};
});
}
{
std::optional<MoveOnly> opt;
opt = std::move(opt).or_else([] { return std::optional<MoveOnly>{MoveOnly{}}; });
std::move(opt).or_else([] {
assert(false);
return std::optional<MoveOnly>{};
});
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
}
|
