40 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++17, c++2010 11// constexpr E&& error() && noexcept;12 13#include <cassert>14#include <concepts>15#include <expected>16#include <utility>17 18template <class T>19concept ErrorNoexcept =20 requires(T&& t) {21 { std::move(t).error() } noexcept;22 };23 24static_assert(!ErrorNoexcept<int>);25static_assert(ErrorNoexcept<std::unexpected<int>>);26 27constexpr bool test() {28 std::unexpected<int> unex(5);29 decltype(auto) i = std::move(unex).error();30 static_assert(std::same_as<decltype(i), int&&>);31 assert(i == 5);32 return true;33}34 35int main(int, char**) {36 test();37 static_assert(test());38 return 0;39}40