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  1. #include <iostream>
  2. #include <typeinfo>
  3. #include <type_traits>
  4. using namespace std;
  5.  
  6. struct A{
  7.     const int a;
  8.     int b;
  9. };
  10.  
  11. template<typename T> struct tmpl;
  12.  
  13. template<typename Class, typename FT> struct tmpl<FT(Class::*)>{
  14.     static void f(){
  15.         if ( std::is_const< FT >::value ) {
  16.             cout<<"const as non const"<<endl;
  17. 	} else {
  18.             cout<<"non const"<<endl;
  19. 	}
  20.     }
  21. };
  22.  
  23. //Try commenting this out, code compiles, both A::a and A::b instantiate the first template
  24. /*template<typename Class, typename FT> struct tmpl<const FT(Class::*)>{
  25.     static void f(){
  26.         cout<<"const"<<endl;
  27.     }
  28. };*/
  29.  
  30. int main(){
  31.     cout<<typeid(&A::a).name()<<endl;   //prints "M1AKi"
  32.     tmpl<decltype(&A::a)>::f();         //prints "const"
  33.     cout<<typeid(&A::b).name()<<endl;   //prints "M1Ai"
  34.     tmpl<decltype(&A::b)>::f();         //prints "non const"
  35.     //Let's do what it seems that can be done implicitly (providing only one template specialization) in an explicit way
  36.     int(A::*memb)= const_cast< int (A::*) >( &A::a );
  37.     cout<<typeid(memb).name()<<endl;    //prints "M1Ai"
  38.     tmpl<decltype(memb)>::f();          //prints "non const"
  39. }
  40.  
Success #stdin #stdout 0s 2828KB
comments (?)
stdin
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Standard input is empty
stdout
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M1AKi
const as non const
M1Ai
non const
M1Ai
non const
https://ideone.com/g2Eie
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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