xref: /llvm-project/libcxx/test/std/utilities/expected/expected.void/assign/emplace.pass.cpp (revision 6a54dfbfe534276d644d7f9c027f0deeb748dd53)
1e356f681SHui Xie //===----------------------------------------------------------------------===//
2*6a54dfbfSLouis Dionne //
3e356f681SHui Xie // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4e356f681SHui Xie // See https://llvm.org/LICENSE.txt for license information.
5e356f681SHui Xie // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6e356f681SHui Xie //
7e356f681SHui Xie //===----------------------------------------------------------------------===//
8e356f681SHui Xie 
9e356f681SHui Xie // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
10e356f681SHui Xie 
11e356f681SHui Xie // constexpr void emplace() noexcept;
12e356f681SHui Xie //
13e356f681SHui Xie // Effects: If has_value() is false, destroys unex and sets has_val to true.
14e356f681SHui Xie 
15e356f681SHui Xie #include <cassert>
16e356f681SHui Xie #include <concepts>
17e356f681SHui Xie #include <expected>
18e356f681SHui Xie #include <type_traits>
19e356f681SHui Xie #include <utility>
20e356f681SHui Xie 
21e356f681SHui Xie #include "../../types.h"
22e356f681SHui Xie #include "test_macros.h"
23e356f681SHui Xie 
24e356f681SHui Xie template <class T>
25e356f681SHui Xie concept EmplaceNoexcept =
26e356f681SHui Xie     requires(T t) {
27e356f681SHui Xie       { t.emplace() } noexcept;
28e356f681SHui Xie     };
29e356f681SHui Xie static_assert(!EmplaceNoexcept<int>);
30e356f681SHui Xie 
31e356f681SHui Xie static_assert(EmplaceNoexcept<std::expected<void, int>>);
32e356f681SHui Xie 
33e356f681SHui Xie constexpr bool test() {
34e356f681SHui Xie   // has_value
35e356f681SHui Xie   {
36e356f681SHui Xie     std::expected<void, int> e;
37e356f681SHui Xie     e.emplace();
38e356f681SHui Xie     assert(e.has_value());
39e356f681SHui Xie   }
40e356f681SHui Xie 
41e356f681SHui Xie   // !has_value
42e356f681SHui Xie   {
43e356f681SHui Xie     Traced::state state{};
44e356f681SHui Xie     std::expected<int, Traced> e(std::unexpect, state, 5);
45e356f681SHui Xie     e.emplace();
46e356f681SHui Xie 
47e356f681SHui Xie     assert(state.dtorCalled);
48e356f681SHui Xie     assert(e.has_value());
49e356f681SHui Xie   }
50e356f681SHui Xie 
51e356f681SHui Xie   return true;
52e356f681SHui Xie }
53e356f681SHui Xie 
54e356f681SHui Xie int main(int, char**) {
55e356f681SHui Xie   test();
56e356f681SHui Xie   static_assert(test());
57e356f681SHui Xie   return 0;
58e356f681SHui Xie }
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