1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // <functional>
10 
11 // template <class T>
12 // struct hash
13 //     : public unary_function<T, size_t>
14 // {
15 //     size_t operator()(T val) const;
16 // };
17 
18 // Not very portable
19 
20 #include <functional>
21 #include <cassert>
22 #include <type_traits>
23 #include <limits>
24 
25 #include "test_macros.h"
26 
27 template <class T>
28 void
29 test()
30 {
31     typedef std::hash<T> H;
32     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
33     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
34     ASSERT_NOEXCEPT(H()(T()));
35     H h;
36 
37     typedef typename std::remove_pointer<T>::type type;
38     type i;
39     type j;
40     assert(h(&i) != h(&j));
41 }
42 
43 // can't hash nullptr_t until C++17
44 void test_nullptr()
45 {
46 #if TEST_STD_VER > 14
47     typedef std::nullptr_t T;
48     typedef std::hash<T> H;
49     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
50     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
51     ASSERT_NOEXCEPT(H()(T()));
52 #endif
53 }
54 
55 int main(int, char**)
56 {
57     test<int*>();
58     test_nullptr();
59 
60   return 0;
61 }
62