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