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 void emplace() noexcept; 12 // 13 // Effects: If has_value() is false, destroys unex and sets has_val to true. 14 15 #include <cassert> 16 #include <concepts> 17 #include <expected> 18 #include <type_traits> 19 #include <utility> 20 21 #include "../../types.h" 22 #include "test_macros.h" 23 24 template <class T> 25 concept EmplaceNoexcept = 26 requires(T t) { 27 { t.emplace() } noexcept; 28 }; 29 static_assert(!EmplaceNoexcept<int>); 30 31 static_assert(EmplaceNoexcept<std::expected<void, int>>); 32 33 constexpr bool test() { 34 // has_value 35 { 36 std::expected<void, int> e; 37 e.emplace(); 38 assert(e.has_value()); 39 } 40 41 // !has_value 42 { 43 Traced::state state{}; 44 std::expected<int, Traced> e(std::unexpect, state, 5); 45 e.emplace(); 46 47 assert(state.dtorCalled); 48 assert(e.has_value()); 49 } 50 51 return true; 52 } 53 54 int main(int, char**) { 55 test(); 56 static_assert(test()); 57 return 0; 58 } 59