1 //===----------------------------------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 // UNSUPPORTED: c++98, c++03, c++11, c++14
11 // <optional>
12 
13 // optional<T>& operator=(const optional<T>& rhs); // constexpr in C++20
14 
15 #include <optional>
16 #include <type_traits>
17 #include <cassert>
18 
19 #include "test_macros.h"
20 #include "archetypes.hpp"
21 
22 using std::optional;
23 
24 struct X
25 {
26     static bool throw_now;
27 
28     X() = default;
XX29     X(const X&)
30     {
31         if (throw_now)
32             TEST_THROW(6);
33     }
34 };
35 
36 bool X::throw_now = false;
37 
38 template <class Tp>
assign_empty(optional<Tp> && lhs)39 constexpr bool assign_empty(optional<Tp>&& lhs) {
40     const optional<Tp> rhs;
41     lhs = rhs;
42     return !lhs.has_value() && !rhs.has_value();
43 }
44 
45 template <class Tp>
assign_value(optional<Tp> && lhs)46 constexpr bool assign_value(optional<Tp>&& lhs) {
47     const optional<Tp> rhs(101);
48     lhs = rhs;
49     return lhs.has_value() && rhs.has_value() && *lhs == *rhs;
50 }
51 
main()52 int main()
53 {
54     {
55         using O = optional<int>;
56 #if TEST_STD_VER > 17
57         LIBCPP_STATIC_ASSERT(assign_empty(O{42}), "");
58         LIBCPP_STATIC_ASSERT(assign_value(O{42}), "");
59 #endif
60         assert(assign_empty(O{42}));
61         assert(assign_value(O{42}));
62     }
63     {
64         using O = optional<TrivialTestTypes::TestType>;
65 #if TEST_STD_VER > 17
66         LIBCPP_STATIC_ASSERT(assign_empty(O{42}), "");
67         LIBCPP_STATIC_ASSERT(assign_value(O{42}), "");
68 #endif
69         assert(assign_empty(O{42}));
70         assert(assign_value(O{42}));
71     }
72     {
73         using O = optional<TestTypes::TestType>;
74         assert(assign_empty(O{42}));
75         assert(assign_value(O{42}));
76     }
77     {
78         using T = TestTypes::TestType;
79         T::reset();
80         optional<T> opt(3);
81         const optional<T> opt2;
82         assert(T::alive == 1);
83         opt = opt2;
84         assert(T::alive == 0);
85         assert(!opt2.has_value());
86         assert(!opt.has_value());
87     }
88 #ifndef TEST_HAS_NO_EXCEPTIONS
89     {
90         optional<X> opt;
91         optional<X> opt2(X{});
92         assert(static_cast<bool>(opt2) == true);
93         try
94         {
95             X::throw_now = true;
96             opt = opt2;
97             assert(false);
98         }
99         catch (int i)
100         {
101             assert(i == 6);
102             assert(static_cast<bool>(opt) == false);
103         }
104     }
105 #endif
106 }
107