GCC gives a fairly meaningful error message if you uncomment (XX):
using typedef-name `AB' after `class'

Indeed,
friend AB;
works just fine. "A<B>" is already "class", no need to say "class AB".



Enno Kehrer wrote:
>
> Hi,
>
> look at code below and tell me why I cannot make a friend declaration to a
> typedefed template class.
> Perhaps this is this a specific vcc issue. Can anyone help me with that ?
>
> class B;
> template <class T>
> class A
> {
>     public:
>         void foo ( B & b )
>         {// Access private data in B
>             std::cout << b.data << std::endl;
>         }
> };
>
> typedef A<B> AB;    // Type substitution:  AB == A<B>
>
> class B
> {
> //  friend class AB;        // (XX) error C2248: 'data' : cannot access
> private member declared in class 'B'
>     friend class A<B>;      // ok
>     public:
>         B () : data(123) {}
>     private:
>         int data;           // Private data
> };
>
> int main(int argc, char* argv[])
> {
>     B b;                    // instance of B
>     AB ab;                  // instance of AB  (  A<B>  )
>                             // -> Activate XX above and you'll get:
>                             // error C2079: 'ab' uses undefined class 'AB'
>     ab.foo( b );            // A access B
>     return 0;
> }
>
> ///// --- End of Code --- /////
>
> ---
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Hi,

look at code below and tell me why I cannot make a friend declaration to a
typedefed template class.
Perhaps this is this a specific vcc issue. Can anyone help me with that ?


class B;
template <class T>
class A
{
    public:
        void foo ( B & b )
        {// Access private data in B
            std::cout << b.data << std::endl;
        }
};

typedef A<B> AB;    // Type substitution:  AB == A<B>

class B
{
//  friend class AB;        // (XX) error C2248: 'data' : cannot access
private member declared in class 'B'
    friend class A<B>;      // ok
    public:
        B () : data(123) {}
    private:
        int data;           // Private data
};


int main(int argc, char* argv[])
{
    B b;                    // instance of B
    AB ab;                  // instance of AB  (  A<B>  )
                            // -> Activate XX above and you'll get:
                            // error C2079: 'ab' uses undefined class 'AB'
    ab.foo( b );            // A access B
    return 0;
}

///// --- End of Code --- /////



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