Re: g++ 3.4.0 : C++ templates' error messages

[llewelly at xmission dot com]

Shelly Adhikari <shelly@interrasystems.com> writes:

> Hello Guys,
> 
> The following code compiled fine with gcc 3.3.3, but is giving me
> errors in gcc 3.4.0. Uncommenting any of the two commented lines,
> removes the error. Is the uncommented code incorrect [an explanation
> or citing the relevant section of the C++ standard would be nice], or
> is it a bug in 3.4.0? If it is not a bug, the error message should be
> made clearer, if possible.
> 
> template <class T> class A;
> template <class T> class B;
> template <class T> class C;
> template <class T> class D;
> 
> template <class T> class A {
> protected:
>     int a;
>     A() { }
>     virtual ~A() { }
>     virtual bool IsB() const = 0;
>     friend class D<T>;
>     friend class C<T>;
> };
> 
> template <class T> class B : public A<T> {
> protected:
>     int b;
>     B() { }
>     virtual ~B() { }
>     bool IsB() const { return true; }
>     bool PB() { return true; }
>     friend class C<T>;
>     friend class D<T>;
>     friend bool C<T>::CC(A<T>* a) const;

The problem is this friend decl. It refers to a protected
    member. "A name nominated by a friend declaration shall be
    accessible in the scope of the class containing the friend
    declaration. " (from 11.4/7)

See http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/cwg_closed.html#209 for
    some discussion.

> };
[snip]