xref: /llvm-project/libcxx/test/std/utilities/optional/optional.nullopt/nullopt_t.pass.cpp (revision 31cbe0f240f660f15602c96b787c58a26f17e179)
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
10 // <optional>
11 
12 // struct nullopt_t{see below};
13 // inline constexpr nullopt_t nullopt(unspecified);
14 
15 // [optional.nullopt]/2:
16 //   Type nullopt_t shall not have a default constructor or an initializer-list
17 //   constructor, and shall not be an aggregate.
18 
19 #include <optional>
20 #include <type_traits>
21 
22 #include "test_macros.h"
23 
24 using std::nullopt_t;
25 using std::nullopt;
26 
test()27 constexpr bool test()
28 {
29     nullopt_t foo{nullopt};
30     (void)foo;
31     return true;
32 }
33 
main(int,char **)34 int main(int, char**)
35 {
36     static_assert(std::is_empty_v<nullopt_t>);
37     static_assert(!std::is_default_constructible_v<nullopt_t>);
38 
39     static_assert(std::is_same_v<const nullopt_t, decltype(nullopt)>);
40     static_assert(test());
41 
42   return 0;
43 }
44