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 // constexpr const T& optional<T>::value() const &;
14 
15 #include <optional>
16 #include <type_traits>
17 #include <cassert>
18 
19 using std::optional;
20 
21 struct X
22 {
testX23     constexpr int test() const {return 3;}
testX24     int test() {return 4;}
25 };
26 
main()27 int main()
28 {
29     {
30         constexpr optional<X> opt;
31         static_assert(opt.value().test() == 3, "");
32     }
33 }
34