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...) const);
13 
14 #include <functional>
15 #include <cassert>
16 
17 #include "test_macros.h"
18 
19 struct A
20 {
21     TEST_CONSTEXPR char test0() const {return 'a';}
22     TEST_CONSTEXPR char test1(int) const {return 'b';}
23     TEST_CONSTEXPR char test2(int, double) const {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 A* cap = &a;
36     assert(f(cap) == 'a');
37     const F& cf = f;
38     assert(cf(ap) == 'a');
39     }
40     return true;
41 }
42 
43 template <class F>
44 TEST_CONSTEXPR_CXX20 bool
45 test1(F f)
46 {
47     {
48     A a;
49     assert(f(a, 1) == 'b');
50     A* ap = &a;
51     assert(f(ap, 2) == 'b');
52     const A* cap = &a;
53     assert(f(cap, 2) == 'b');
54     const F& cf = f;
55     assert(cf(ap, 2) == 'b');
56     }
57     return true;
58 }
59 
60 template <class F>
61 TEST_CONSTEXPR_CXX20 bool
62 test2(F f)
63 {
64     {
65     A a;
66     assert(f(a, 1, 2) == 'c');
67     A* ap = &a;
68     assert(f(ap, 2, 3.5) == 'c');
69     const A* cap = &a;
70     assert(f(cap, 2, 3.5) == 'c');
71     const F& cf = f;
72     assert(cf(ap, 2, 3.5) == 'c');
73     }
74     return true;
75 }
76 
77 int main(int, char**)
78 {
79     test0(std::mem_fn(&A::test0));
80     test1(std::mem_fn(&A::test1));
81     test2(std::mem_fn(&A::test2));
82 
83 #if TEST_STD_VER >= 20
84     static_assert(test0(std::mem_fn(&A::test0)));
85     static_assert(test1(std::mem_fn(&A::test1)));
86     static_assert(test2(std::mem_fn(&A::test2)));
87 #endif
88 
89     return 0;
90 }
91