81 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// REQUIRES: std-at-least-c++2610 11// <optional>12 13// constexpr iterator optional::end() noexcept;14// constexpr const_iterator optional::end() const noexcept;15 16#include <cassert>17#include <iterator>18#include <optional>19#include <ranges>20#include <type_traits>21#include <utility>22 23template <typename T>24constexpr bool test() {25 std::optional<T> disengaged{std::nullopt};26 27 { // end() is marked noexcept28 static_assert(noexcept(disengaged.end()));29 static_assert(noexcept(std::as_const(disengaged).end()));30 }31 32 { // end() == begin() and end() == end() if the optional is disengaged33 auto it = disengaged.end();34 auto it2 = std::as_const(disengaged).end();35 36 assert(it == disengaged.begin());37 assert(disengaged.begin() == it);38 assert(it == disengaged.end());39 40 assert(it2 == std::as_const(disengaged).begin());41 assert(std::as_const(disengaged).begin() == it2);42 assert(it2 == std::as_const(disengaged).end());43 }44 45 std::remove_reference_t<T> t = std::remove_reference_t<T>{};46 std::optional<T> engaged{t};47 48 { // end() != begin() if the optional is engaged49 auto it = engaged.end();50 auto it2 = std::as_const(engaged).end();51 52 assert(it != engaged.begin());53 assert(engaged.begin() != it);54 55 assert(it2 != std::as_const(engaged).begin());56 assert(std::as_const(engaged).begin() != it2);57 }58 59 return true;60}61 62constexpr bool tests() {63 assert(test<int>());64 assert(test<char>());65 assert(test<const int>());66 assert(test<const char>());67 assert(test<int&>());68 assert(test<char&>());69 assert(test<const int&>());70 assert(test<const char&>());71 72 return true;73}74 75int main(int, char**) {76 assert(tests());77 static_assert(tests());78 79 return 0;80}81