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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 #include <functional>
     11 #include <string>
     12 
     13 template <class _Tp>
     14 struct is_transparent
     15 {
     16 private:
     17     struct __two {char __lx; char __lxx;};
     18     template <class _Up> static __two __test(...);
     19     template <class _Up> static char __test(typename _Up::is_transparent* = 0);
     20 public:
     21     static const bool value = sizeof(__test<_Tp>(0)) == 1;
     22 };
     23 
     24 
     25 int main () {
     26 #if _LIBCPP_STD_VER > 11
     27 
     28     static_assert ( !is_transparent<std::less<int>>::value, "" );
     29     static_assert ( !is_transparent<std::less<std::string>>::value, "" );
     30     static_assert (  is_transparent<std::less<void>>::value, "" );
     31     static_assert (  is_transparent<std::less<>>::value, "" );
     32 
     33     static_assert ( !is_transparent<std::less_equal<int>>::value, "" );
     34     static_assert ( !is_transparent<std::less_equal<std::string>>::value, "" );
     35     static_assert (  is_transparent<std::less_equal<void>>::value, "" );
     36     static_assert (  is_transparent<std::less_equal<>>::value, "" );
     37 
     38     static_assert ( !is_transparent<std::equal_to<int>>::value, "" );
     39     static_assert ( !is_transparent<std::equal_to<std::string>>::value, "" );
     40     static_assert (  is_transparent<std::equal_to<void>>::value, "" );
     41     static_assert (  is_transparent<std::equal_to<>>::value, "" );
     42 
     43     static_assert ( !is_transparent<std::not_equal_to<int>>::value, "" );
     44     static_assert ( !is_transparent<std::not_equal_to<std::string>>::value, "" );
     45     static_assert (  is_transparent<std::not_equal_to<void>>::value, "" );
     46     static_assert (  is_transparent<std::not_equal_to<>>::value, "" );
     47 
     48     static_assert ( !is_transparent<std::greater<int>>::value, "" );
     49     static_assert ( !is_transparent<std::greater<std::string>>::value, "" );
     50     static_assert (  is_transparent<std::greater<void>>::value, "" );
     51     static_assert (  is_transparent<std::greater<>>::value, "" );
     52 
     53     static_assert ( !is_transparent<std::greater_equal<int>>::value, "" );
     54     static_assert ( !is_transparent<std::greater_equal<std::string>>::value, "" );
     55     static_assert (  is_transparent<std::greater_equal<void>>::value, "" );
     56     static_assert (  is_transparent<std::greater_equal<>>::value, "" );
     57 
     58 #endif
     59 
     60     return 0;
     61     }
     62