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  1.     #include <type_traits>
  2.     #include <iterator>
  3.     #include <list>
  4.     #include <vector>
  5.  
  6.     template<typename T, typename = void>
  7.     struct is_const_iterator : std::false_type { };
  8.  
  9.     template<typename T>
  10.     struct is_const_iterator<T,
  11.         typename std::enable_if<
  12.             std::is_const<
  13.                 typename std::remove_pointer<
  14.                     typename std::iterator_traits<T>::pointer
  15.                     >::type
  16.                 >::value
  17.             >::type> : std::true_type { };
  18.  
  19.     int main()
  20.     {
  21.         typedef std::list<int>::iterator LI;
  22.         typedef std::list<int>::const_iterator CLI;
  23.         static_assert(is_const_iterator<LI>::value, "!"); // Fires
  24.         static_assert(is_const_iterator<CLI>::value, "!"); // Does not fire
  25.  
  26.         typedef std::vector<int>::iterator VI;
  27.         typedef std::vector<int>::const_iterator CVI;
  28.         static_assert(is_const_iterator<VI>::value, "!"); // Fires
  29.         static_assert(is_const_iterator<CVI>::value, "!"); // Does not fire
  30.     }
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
prog.cpp: In function ‘int main()’:
prog.cpp:23:9: error: static assertion failed: !
prog.cpp:28:9: error: static assertion failed: !
stdout
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Standard output is empty
https://ideone.com/4v2mqi
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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