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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. class A {};
  5. class B {};
  6.  
  7. class C {
  8. public:
  9.  
  10.     template <typename T>
  11.     void f() {
  12.         // T = const B&
  13.         impl_dispatch<T>(); // error: value-initialization of reference type ‘const B&’
  14.     }
  15.  
  16. protected:
  17.     virtual void impl(const A& a) {
  18.         cout << "A";
  19.     }
  20.  
  21.     virtual void impl(const B& b) {
  22.         cout << "B";
  23.     }
  24. private:
  25.    template <typename T>
  26.    void impl_dispatch();
  27. };
  28.  
  29. template <>  void C::impl_dispatch<A const &>()
  30. {
  31. impl(B());
  32. }
  33.  
  34. template <>  void C::impl_dispatch<B const &>()
  35. {
  36. impl(A());
  37. }
  38.  
  39. int main() {
  40.     C c;
  41.     const B &b2 = B();
  42.     c.f<decltype(b2)>(); // T = const B&
  43.     return 0;
  44. }
Success #stdin #stdout 0s 3296KB
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A
https://ideone.com/J87MUo
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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