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Calling virtual method of base class nested in template class

Roger <some...@idontwantspam.com>

Hi all.

Here's a little quandry I've run in to and can't tell if it's a compiler
bug, or if it's bad code.  First, here's the code:

===================================
#include <stdio.h>

template < typename T >
class B
{

public:

  B( ) { }

  class N1
  {

  public:

    N1( ) { };

    class N2
    {

    public:

      N2( ) { };

      virtual void f( )
      {
        printf( " B< >::N1::N2::f( )\n" );
      }

    };

  };

  T _m;

};

class D : public B< int >
{

public:

  class N1 : public B< int >::N1
  {

  public:

    N1( ) : B< int >::N1( ) { };

    class N2 : public B< int >::N1::N2
    {

    public:

      N2( ) : B< int >::N1::N2( ) { };

      virtual void f( )
      {
        printf( " D::N1::N2::f( )\n" );
        ( ( B< int >::N1::N2* ) this )->f( );
      }

    };

  };

};

void
main( int argc, char* argv[ ] )
{
  D::N1::N2 n2;

  n2.f( );

}

==================================

Invoking n2.f( ) causes an infinite loop, dumping out "D::N1::N2::f( )"
ad-nausium.  I am trying to call the base-class f( ) in B::N1::N2, but the
compiler just generates code that instead calls D::N1::N2::f( ) recursively.

What am I doning wrong?  How can I call the base's f( )?

Thanks for any help you can offer!

- Roger

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