Re: Impossible compilation scenario!! (possible BUG)

From:
"Doug Harrison [MVP]" <dsh@mvps.org>
Newsgroups:
microsoft.public.vc.language
Date:
Sun, 02 Dec 2007 12:06:22 -0600
Message-ID:
<lms5l3l46lvj89pfodo8s2piql6v51nqdi@4ax.com>
On Sun, 2 Dec 2007 18:55:10 +0100, "Abdulla Herzallah" <ah@herz.dk> wrote:

It seems that the forward declaration does not work if the class is used in
the inheritance declartion statment
the code below (compiled in Native C++ Console application) illustrate it
(as this does not work in VS2008 and that it is the latest compiler I assume
then, that VS2005 will not work either (but I have not tried it on VS2005)

What I could be missing some compiler directive!!! well please help me
here guys ( I am desperate now)

The error I keep getting C2504 Base class undefined

No matter what I tried to re-arrange the order of these classes I get the
same error for one of these classes

below is the complete code (i.e. no .h files to include in the stdfx.h)

#include "stdafx.h"

template<typename T> class Base; // forward declaring Base

class First : Base<First> { }; // >>breaking here as Base class is
undfined<<

template <typename T> class Second: First { };

template<typename T> class Base: Second<T> { };

int _tmain(int argc, _TCHAR* argv[])
{
return 0;
}


This fails, too, and for the same reason:

template<typename T> class Base; // forward declaring Base
Base<int> x;

In both cases, a completed class definition is required.

--
Doug Harrison
Visual C++ MVP

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