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// <optional>
11
12// template <class U> constexpr T optional<T>::value_or(U&& v) const&;
13
14#include <experimental/optional>
15#include <type_traits>
16#include <cassert>
17
18#if _LIBCPP_STD_VER > 11
19
20using std::experimental::optional;
21
22struct Y
23{
24    int i_;
25
26    constexpr Y(int i) : i_(i) {}
27};
28
29struct X
30{
31    int i_;
32
33    constexpr X(int i) : i_(i) {}
34    constexpr X(const Y& y) : i_(y.i_) {}
35    constexpr X(Y&& y) : i_(y.i_+1) {}
36    friend constexpr bool operator==(const X& x, const X& y)
37        {return x.i_ == y.i_;}
38};
39
40#endif  // _LIBCPP_STD_VER > 11
41
42int main()
43{
44#if _LIBCPP_STD_VER > 11
45    {
46        constexpr optional<X> opt(2);
47        constexpr Y y(3);
48        static_assert(opt.value_or(y) == 2, "");
49    }
50    {
51        constexpr optional<X> opt(2);
52        static_assert(opt.value_or(Y(3)) == 2, "");
53    }
54    {
55        constexpr optional<X> opt;
56        constexpr Y y(3);
57        static_assert(opt.value_or(y) == 3, "");
58    }
59    {
60        constexpr optional<X> opt;
61        static_assert(opt.value_or(Y(3)) == 4, "");
62    }
63    {
64        const optional<X> opt(2);
65        const Y y(3);
66        assert(opt.value_or(y) == 2);
67    }
68    {
69        const optional<X> opt(2);
70        assert(opt.value_or(Y(3)) == 2);
71    }
72    {
73        const optional<X> opt;
74        const Y y(3);
75        assert(opt.value_or(y) == 3);
76    }
77    {
78        const optional<X> opt;
79        assert(opt.value_or(Y(3)) == 4);
80    }
81#endif  // _LIBCPP_STD_VER > 11
82}
83