“No matching function for call error” with g++

Question

I have a class A

template
class A : public std::auto_ptr
{
    typedef std::auto_ptr Super;
public:
    A() : Super() { }
            


        

Answer 1

Your A copy constructor takes its argument by non-const reference:

A(A& o) : Super(o) { }
      ^ not const

Your example probably tries to copy a temporary object and the non-const reference can't bind to the temporary object. Visual C++ has an evil extension that allows this to work; you have to be careful to avoid relying on that extension if you want your code to be portable.

If you are trying to mimic auto_ptr's copy constructor, you need to also implement something similar to auto_ptr_ref, which is used as a helper to allow copying temporary auto_ptrs. I describe how this is accomplished in the accepted answer to How could one implement std::auto_ptr's copy constructor?

For what it's worth, deriving from std::auto_ptr is a bit odd; consider using composition instead of inheritance, if you can (there isn't a whole lot in std::auto_ptr that you'd benefit from by deriving from it anyway).