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 T> struct hash<optional<T>>;
14 
15 #include <optional>
16 #include <string>
17 #include <memory>
18 #include <cassert>
19 
20 
21 int main()
22 {
23     using std::optional;
24     const std::size_t nullopt_hash =
25         std::hash<optional<double>>{}(optional<double>{});
26 
27     {
28         typedef int T;
29         optional<T> opt;
30         assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
31         opt = 2;
32         assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
33     }
34     {
35         typedef std::string T;
36         optional<T> opt;
37         assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
38         opt = std::string("123");
39         assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
40     }
41     {
42         typedef std::unique_ptr<int> T;
43         optional<T> opt;
44         assert(std::hash<optional<T>>{}(opt) == nullopt_hash);
45         opt = std::unique_ptr<int>(new int(3));
46         assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
47     }
48 }
49