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++98, c++03, c++11, c++14
10 // <optional>
11 
12 // constexpr T& optional<T>::operator*() &;
13 
14 #ifdef _LIBCPP_DEBUG
15 #define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
16 #endif
17 
18 #include <optional>
19 #include <type_traits>
20 #include <cassert>
21 
22 #include "test_macros.h"
23 
24 using std::optional;
25 
26 struct X
27 {
28     constexpr int test() const& {return 3;}
29     int test() & {return 4;}
30     constexpr int test() const&& {return 5;}
31     int test() && {return 6;}
32 };
33 
34 struct Y
35 {
36     constexpr int test() {return 7;}
37 };
38 
39 constexpr int
40 test()
41 {
42     optional<Y> opt{Y{}};
43     return (*opt).test();
44 }
45 
46 int main(int, char**)
47 {
48     {
49         optional<X> opt; ((void)opt);
50         ASSERT_SAME_TYPE(decltype(*opt), X&);
51         // ASSERT_NOT_NOEXCEPT(*opt);
52         // FIXME: This assertion fails with GCC because it can see that
53         // (A) operator*() is constexpr, and
54         // (B) there is no path through the function that throws.
55         // It's arguable if this is the correct behavior for the noexcept
56         // operator.
57         // Regardless this function should still be noexcept(false) because
58         // it has a narrow contract.
59     }
60     {
61         optional<X> opt(X{});
62         assert((*opt).test() == 4);
63     }
64     static_assert(test() == 7, "");
65 #ifdef _LIBCPP_DEBUG
66     {
67         optional<X> opt;
68         assert((*opt).test() == 3);
69         assert(false);
70     }
71 #endif  // _LIBCPP_DEBUG
72 
73   return 0;
74 }
75