60 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// template<class U> constexpr T value_or(U&& v) const &;12// template<class U> constexpr T value_or(U&& v) &&;13 14#include <cassert>15#include <concepts>16#include <expected>17#include <type_traits>18#include <utility>19 20#include "MoveOnly.h"21#include "test_macros.h"22 23constexpr bool test() {24 // const &, has_value()25 {26 const std::expected<int, int> e(5);27 std::same_as<int> decltype(auto) x = e.value_or(10);28 assert(x == 5);29 }30 31 // const &, !has_value()32 {33 const std::expected<int, int> e(std::unexpect, 5);34 std::same_as<int> decltype(auto) x = e.value_or(10);35 assert(x == 10);36 }37 38 // &&, has_value()39 {40 std::expected<MoveOnly, int> e(std::in_place, 5);41 std::same_as<MoveOnly> decltype(auto) x = std::move(e).value_or(10);42 assert(x == 5);43 }44 45 // &&, !has_value()46 {47 std::expected<MoveOnly, int> e(std::unexpect, 5);48 std::same_as<MoveOnly> decltype(auto) x = std::move(e).value_or(10);49 assert(x == 10);50 }51 52 return true;53}54 55int main(int, char**) {56 test();57 static_assert(test());58 return 0;59}60