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 const E&& error() const && noexcept;
12 
13 #include <cassert>
14 #include <concepts>
15 #include <expected>
16 #include <utility>
17 
18 template <class T>
19 concept ErrorNoexcept =
20     requires(const T&& t) {
21       { std::move(t).error() } noexcept;
22     };
23 
24 static_assert(!ErrorNoexcept<int>);
25 static_assert(ErrorNoexcept<std::unexpected<int>>);
26 
27 constexpr bool test() {
28   const std::unexpected<int> unex(5);
29   decltype(auto) i = std::move(unex).error();
30   static_assert(std::same_as<decltype(i), const int&&>);
31   assert(i == 5);
32   return true;
33 }
34 
35 int main(int, char**) {
36   test();
37   static_assert(test());
38   return 0;
39 }
40