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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 // <functional>
     11 
     12 // template <class T>
     13 // struct hash
     14 //     : public unary_function<T, size_t>
     15 // {
     16 //     size_t operator()(T val) const;
     17 // };
     18 
     19 // Not very portable
     20 
     21 #include <functional>
     22 #include <cassert>
     23 #include <type_traits>
     24 #include <limits>
     25 
     26 template <class T>
     27 void
     28 test()
     29 {
     30     static_assert((std::is_base_of<std::unary_function<T, std::size_t>,
     31                                    std::hash<T> >::value), "");
     32     std::hash<T> h;
     33     typedef typename std::remove_pointer<T>::type type;
     34     type i;
     35     type j;
     36     assert(h(&i) != h(&j));
     37 }
     38 
     39 int main()
     40 {
     41     test<int*>();
     42 }
     43