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// constexpr const E& error() const & noexcept;
11// constexpr E& error() & noexcept;
12// constexpr E&& error() && noexcept;
13// constexpr const E&& error() const && noexcept;
14
15#include <cassert>
16#include <concepts>
17#include <expected>
18#include <type_traits>
19#include <utility>
20
21#include "test_macros.h"
22
23// Test noexcept
24template <class T>
25concept ErrorNoexcept =
26 requires(T t) {
27 { std::forward<T>(t).error() } noexcept;
28 };
29
30static_assert(!ErrorNoexcept<int>);
31
32static_assert(ErrorNoexcept<std::expected<int, int>&>);
33static_assert(ErrorNoexcept<const std::expected<int, int>&>);
34static_assert(ErrorNoexcept<std::expected<int, int>&&>);
35static_assert(ErrorNoexcept<const std::expected<int, int>&&>);
36
37constexpr bool test() {
38 // non-const &
39 {
40 std::expected<int, int> e(std::unexpect, 5);
41 decltype(auto) x = e.error();
42 static_assert(std::same_as<decltype(x), int&>);
43 assert(x == 5);
44 }
45
46 // const &
47 {
48 const std::expected<int, int> e(std::unexpect, 5);
49 decltype(auto) x = e.error();
50 static_assert(std::same_as<decltype(x), const int&>);
51 assert(x == 5);
52 }
53
54 // non-const &&
55 {
56 std::expected<int, int> e(std::unexpect, 5);
57 decltype(auto) x = std::move(e).error();
58 static_assert(std::same_as<decltype(x), int&&>);
59 assert(x == 5);
60 }
61
62 // const &&
63 {
64 const std::expected<int, int> e(std::unexpect, 5);
65 decltype(auto) x = std::move(e).error();
66 static_assert(std::same_as<decltype(x), const int&&>);
67 assert(x == 5);
68 }
69
70 return true;
71}
72
73int main(int, char**) {
74 test();
75 static_assert(test());
76 return 0;
77}
78

source code of libcxx/test/std/utilities/expected/expected.expected/observers/error.pass.cpp