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 // <functional>
11 
12 // template <class T>
13 // struct hash
14 //     : public unary_function<T, size_t>
15 // {
16 //     size_t operator()(T val) const;
17 // };
18 
19 // Not very portable
20 
21 #include <system_error>
22 #include <cassert>
23 #include <type_traits>
24 
25 void
test(int i)26 test(int i)
27 {
28     typedef std::error_code T;
29     typedef std::hash<T> H;
30     static_assert((std::is_base_of<std::unary_function<T, std::size_t>,
31                                    H>::value), "");
32     H h;
33     T ec(i, std::system_category());
34     assert(h(ec) == i);
35 }
36 
main()37 int main()
38 {
39     test(0);
40     test(2);
41     test(10);
42 }
43