[Bug c++/19288] No more possible to have a template function that uses a nested class of a template class

["jean-pierre dot chevallet at imag dot fr" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From jean-pierre dot chevallet at imag dot fr  2005-01-10 05:56 -------
(In reply to comment #7)
> You are trying to overload operator<<(std::ostream, float). That 
> can't work, since there is already an overload for that. 
>  
> W. 

I don't think so, I try to define un fonction like this :

operator<<(std::ostream, C1<float>::nested&) with is not an overload of
operator<<(std::ostream, float).

The lesson I learn from all your replies : 
nested class of a template wich have no template
parametrer are difficult to use due to the notion nondeducible context.
I think it is better to avoid non template nested class, or adding a
explicit template parameter to the nested class, like :

template <typename T> class C1 {
public:
  T V;
  C1(T v) : V(v) {};
  
  template <typename U>
  class nested {
  public:
    U W;
    nested(U w) : W(w) {};
  };  
};
// Template version of operator using nested temptate class
template <typename T>
ostream&  operator << (ostream& out,typename C1<T>::nested<T>& c) {return
out<<c.W; }

  C1<float>::nested<float> n(3.5);

  cout<<n<<endl; // Here find the correct instantiation

or not use nested template class at all ........




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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19288