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 // template<class... Args> 12 // constexpr explicit unexpected(in_place_t, Args&&... args); 13 // 14 // Constraints: is_constructible_v<E, Args...> is true. 15 // 16 // Effects: Direct-non-list-initializes unex with std::forward<Args>(args).... 17 // 18 // Throws: Any exception thrown by the initialization of unex. 19 20 #include <cassert> 21 #include <concepts> 22 #include <expected> 23 #include <utility> 24 25 #include "test_macros.h" 26 27 // Test Constraints: 28 static_assert(std::constructible_from<std::unexpected<int>, std::in_place_t, int>); 29 30 // !is_constructible_v<E, Args...> 31 struct Foo {}; 32 static_assert(!std::constructible_from<std::unexpected<Foo>, std::in_place_t, int>); 33 34 // test explicit 35 template <class T> 36 void conversion_test(T); 37 38 template <class T, class... Args> 39 concept ImplicitlyConstructible = requires(Args&&... args) { conversion_test<T>({std::forward<Args>(args)...}); }; 40 41 static_assert(ImplicitlyConstructible<int, int>); 42 static_assert(!ImplicitlyConstructible<std::unexpected<int>, std::in_place_t, int>); 43 44 struct Arg { 45 int i; 46 constexpr Arg(int ii) : i(ii) {} 47 constexpr Arg(const Arg& other) : i(other.i) {} 48 constexpr Arg(Arg&& other) : i(other.i) { other.i = 0; } 49 }; 50 51 struct Error { 52 Arg arg; 53 constexpr explicit Error(const Arg& a) : arg(a) {} 54 constexpr explicit Error(Arg&& a) : arg(std::move(a)) {} 55 Error(std::initializer_list<Error>) :arg(0){ assert(false); } 56 }; 57 58 constexpr bool test() { 59 // lvalue 60 { 61 Arg a{5}; 62 std::unexpected<Error> unex(std::in_place, a); 63 assert(unex.error().arg.i == 5); 64 assert(a.i == 5); 65 } 66 67 // rvalue 68 { 69 Arg a{5}; 70 std::unexpected<Error> unex(std::in_place, std::move(a)); 71 assert(unex.error().arg.i == 5); 72 assert(a.i == 0); 73 } 74 75 // Direct-non-list-initializes: does not trigger initializer_list overload 76 { 77 Error e(5); 78 [[maybe_unused]] std::unexpected<Error> unex(std::in_place, e); 79 } 80 return true; 81 } 82 83 void testException() { 84 #ifndef TEST_HAS_NO_EXCEPTIONS 85 struct Except {}; 86 87 struct Throwing { 88 Throwing(int) { throw Except{}; } 89 }; 90 91 try { 92 std::unexpected<Throwing> u(std::in_place, 5); 93 assert(false); 94 } catch (Except) { 95 } 96 #endif // TEST_HAS_NO_EXCEPTIONS 97 } 98 99 int main(int, char**) { 100 test(); 101 static_assert(test()); 102 testException(); 103 return 0; 104 } 105