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  1. #include <iostream>
  2.  
  3. template < typename T > void foo( T, typename T::const_iterator* = nullptr )
  4. { std::cout << "(1) this type defines a nested type 'const_iterator'\n" ; }
  5.  
  6. template < typename T > void foo( T, typename T::first_type* = nullptr )
  7. { std::cout << "(2) this type defines a nested type 'first_type'\n" ; }
  8.  
  9. template < typename T > void foo( T, typename T::result_type* = nullptr )
  10. { std::cout << "(3) this type defines a nested type 'result_type'\n" ; }
  11.  
  12. #include <vector>
  13. #include <utility>
  14. #include <functional>
  15.  
  16. int main()
  17. {
  18.     std::vector<int> a ;
  19.     foo(a) ; // (1) this type defines a nested type 'const_iterator'
  20.     // substitution failure for (2) and (3)
  21.  
  22.     std::pair<int,int> b ;
  23.     foo(b) ; // (2) this type defines a nested type 'first_type'
  24.     // substitution failure for (1) and (3)
  25.  
  26.     std::function< bool(int,int) > c ;
  27.     foo(c) ; // (3) this type defines a nested type 'result_type'
  28.     // substitution failure for (1) and (2)
  29. }
  30.  
Success #stdin #stdout 0s 2852KB
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stdin
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Standard input is empty
stdout
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(1) this type defines a nested type 'const_iterator'
(2) this type defines a nested type 'first_type'
(3) this type defines a nested type 'result_type'
https://ideone.com/xRwbNm
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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