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<Returnable R, class T, CopyConstructible... Args>
12 //   unspecified mem_fn(R (T::* pm)(Args...));
13 
14 #include <functional>
15 #include <cassert>
16 
17 #include "test_macros.h"
18 
19 struct A
20 {
21     TEST_CONSTEXPR_CXX14 char test0() {return 'a';}
22     TEST_CONSTEXPR_CXX14 char test1(int) {return 'b';}
23     TEST_CONSTEXPR_CXX14 char test2(int, double) {return 'c';}
24 };
25 
26 template <class F>
27 TEST_CONSTEXPR_CXX20 bool
28 test0(F f)
29 {
30     {
31     A a;
32     assert(f(a) == 'a');
33     A* ap = &a;
34     assert(f(ap) == 'a');
35     const F& cf = f;
36     assert(cf(ap) == 'a');
37     }
38     return true;
39 }
40 
41 template <class F>
42 TEST_CONSTEXPR_CXX20 bool
43 test1(F f)
44 {
45     {
46     A a;
47     assert(f(a, 1) == 'b');
48     A* ap = &a;
49     assert(f(ap, 2) == 'b');
50     const F& cf = f;
51     assert(cf(ap, 2) == 'b');
52     }
53     return true;
54 }
55 
56 template <class F>
57 TEST_CONSTEXPR_CXX20 bool
58 test2(F f)
59 {
60     {
61     A a;
62     assert(f(a, 1, 2) == 'c');
63     A* ap = &a;
64     assert(f(ap, 2, 3.5) == 'c');
65     const F& cf = f;
66     assert(cf(ap, 2, 3.5) == 'c');
67     }
68     return true;
69 }
70 
71 int main(int, char**)
72 {
73     test0(std::mem_fn(&A::test0));
74     test1(std::mem_fn(&A::test1));
75     test2(std::mem_fn(&A::test2));
76 #if TEST_STD_VER >= 11
77     static_assert((noexcept(std::mem_fn(&A::test0))), ""); // LWG#2489
78 #endif
79 
80 #if TEST_STD_VER >= 20
81     static_assert(test0(std::mem_fn(&A::test0)));
82     static_assert(test1(std::mem_fn(&A::test1)));
83     static_assert(test2(std::mem_fn(&A::test2)));
84 #endif
85 
86     return 0;
87 }
88