xref: /llvm-project/libcxx/test/std/utilities/expected/expected.expected/observers/arrow.pass.cpp (revision 6a54dfbfe534276d644d7f9c027f0deeb748dd53)
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 const T* operator->() const noexcept;
12 // constexpr T* operator->() noexcept;
13 
14 #include <cassert>
15 #include <concepts>
16 #include <expected>
17 #include <type_traits>
18 #include <utility>
19 
20 #include "test_macros.h"
21 
22 // Test noexcept
23 template <class T>
24 concept ArrowNoexcept =
25     requires(T t) {
26       { t.operator->() } noexcept;
27     };
28 
29 static_assert(!ArrowNoexcept<int>);
30 
31 static_assert(ArrowNoexcept<std::expected<int, int>>);
32 static_assert(ArrowNoexcept<const std::expected<int, int>>);
33 
34 constexpr bool test() {
35   // const
36   {
37     const std::expected<int, int> e(5);
38     std::same_as<const int*> decltype(auto) x = e.operator->();
39     assert(x == &(e.value()));
40     assert(*x == 5);
41   }
42 
43   // non-const
44   {
45     std::expected<int, int> e(5);
46     std::same_as<int*> decltype(auto) x = e.operator->();
47     assert(x == &(e.value()));
48     assert(*x == 5);
49   }
50 
51   return true;
52 }
53 
54 int main(int, char**) {
55   test();
56   static_assert(test());
57   return 0;
58 }
59