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 // template <class U>
14 //   optional(optional<U>&& rhs);
15 
16 #include <optional>
17 #include <type_traits>
18 #include <memory>
19 #include <cassert>
20 
21 #include "test_macros.h"
22 
23 using std::optional;
24 
25 template <class T, class U>
26 void
27 test(optional<U>&& rhs, bool is_going_to_throw = false)
28 {
29     bool rhs_engaged = static_cast<bool>(rhs);
30 #ifndef TEST_HAS_NO_EXCEPTIONS
31     try
32     {
33         optional<T> lhs = std::move(rhs);
34         assert(is_going_to_throw == false);
35         assert(static_cast<bool>(lhs) == rhs_engaged);
36     }
37     catch (int i)
38     {
39         assert(i == 6);
40     }
41 #else
42     if (is_going_to_throw) return;
43     optional<T> lhs = std::move(rhs);
44     assert(static_cast<bool>(lhs) == rhs_engaged);
45 #endif
46 }
47 
48 class X
49 {
50     int i_;
51 public:
52     X(int i) : i_(i) {}
53     X(X&& x) : i_(std::exchange(x.i_, 0)) {}
54     ~X() {i_ = 0;}
55     friend bool operator==(const X& x, const X& y) {return x.i_ == y.i_;}
56 };
57 
58 int count = 0;
59 
60 struct Z
61 {
62     Z(int) { TEST_THROW(6); }
63 };
64 
65 int main()
66 {
67     {
68         optional<short> rhs;
69         test<int>(std::move(rhs));
70     }
71     {
72         optional<short> rhs(short{3});
73         test<int>(std::move(rhs));
74     }
75     {
76         optional<int> rhs;
77         test<X>(std::move(rhs));
78     }
79     {
80         optional<int> rhs(3);
81         test<X>(std::move(rhs));
82     }
83     {
84         optional<int> rhs;
85         test<Z>(std::move(rhs));
86     }
87     {
88         optional<int> rhs(3);
89         test<Z>(std::move(rhs), true);
90     }
91 
92     static_assert(!(std::is_constructible<optional<X>, optional<Z>>::value), "");
93 }
94