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 // <memory>
10 
11 // template <class Ptr>
12 // struct pointer_traits
13 // {
14 //     static pointer pointer_to(<details>);
15 //     ...
16 // };
17 
18 #include <memory>
19 #include <cassert>
20 
21 template <class T>
22 struct A
23 {
24 private:
25     struct nat {};
26 public:
27     typedef T element_type;
28     element_type* t_;
29 
30     A(element_type* t) : t_(t) {}
31 
32     static A pointer_to(typename std::conditional<std::is_void<element_type>::value,
33                                            nat, element_type>::type& et)
34         {return A(&et);}
35 };
36 
37 int main()
38 {
39     {
40         int i = 0;
41         static_assert((std::is_same<A<int>, decltype(std::pointer_traits<A<int> >::pointer_to(i))>::value), "");
42         A<int> a = std::pointer_traits<A<int> >::pointer_to(i);
43         assert(a.t_ == &i);
44     }
45     {
46         (std::pointer_traits<A<void> >::element_type)0;
47     }
48 }
49