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 // T& optional<T>::value();
13 
14 #include <experimental/optional>
15 #include <type_traits>
16 #include <cassert>
17 
18 #if _LIBCPP_STD_VER > 11
19 
20 using std::experimental::optional;
21 using std::experimental::bad_optional_access;
22 
23 struct X
24 {
25     X() = default;
26     X(const X&) = delete;
testX27     constexpr int test() const {return 3;}
testX28     int test() {return 4;}
29 };
30 
31 #endif  // _LIBCPP_STD_VER > 11
32 
main()33 int main()
34 {
35 #if _LIBCPP_STD_VER > 11
36     {
37         optional<X> opt;
38         opt.emplace();
39         assert(opt.value().test() == 4);
40     }
41     {
42         optional<X> opt;
43         try
44         {
45             opt.value();
46             assert(false);
47         }
48         catch (const bad_optional_access&)
49         {
50         }
51     }
52 #endif  // _LIBCPP_STD_VER > 11
53 }
54