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 
11 // <optional>
12 
13 // template <class T> constexpr bool operator<(const optional<T>& x, nullopt_t) noexcept;
14 // template <class T> constexpr bool operator<(nullopt_t, const optional<T>& x) noexcept;
15 
16 #include <experimental/optional>
17 
main()18 int main()
19 {
20 #if _LIBCPP_STD_VER > 11
21     using std::experimental::optional;
22     using std::experimental::nullopt_t;
23     using std::experimental::nullopt;
24 
25     {
26     typedef int T;
27     typedef optional<T> O;
28 
29     constexpr O o1;     // disengaged
30     constexpr O o2{1};  // engaged
31 
32     static_assert ( !(nullopt < o1), "" );
33     static_assert (  (nullopt < o2), "" );
34     static_assert ( !(o1 < nullopt), "" );
35     static_assert ( !(o2 < nullopt), "" );
36 
37     static_assert (noexcept(nullopt < o1), "");
38     static_assert (noexcept(o1 < nullopt), "");
39     }
40 #endif
41 }
42