Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!godzilla!kohlrabi!robert
From: robert@kohlrabi.tcs.com (Robert Blumen)
Newsgroups: comp.lang.c++
Subject: Re: Virtual function problem.
Keywords: C++ virtual function
Message-ID: <2164@godzilla.tcs.com>
Date: 9 May 91 20:31:05 GMT
References: <3472@trlluna.trl.oz>
Sender: root@tcs.com
Reply-To: robert@kohlrabi.tcs.com (Robert Blumen)
Organization: Teknekron Communications Systems
Lines: 32


In article <3472@trlluna.trl.oz>, mcf@tardis.trl.OZ.AU (Michael Flower) writes:
|> If I compile the following with the AT&T 2.1 C++ compiler:
|> 
|> class A {
|> 	virtual void	fn(char);	// 1
|> 	virtual void	fn(char *);	// 2
|> };
|> 
|> class B : public A {
|> 	void	fn(int);
|> };
|> 
|> in the following way, I get.
|> 
|> "t.c", line 7: warning:  B::fn() hides virtual A::fn()
|> "t.c", line 7: warning:  B::fn() hides virtual A::fn()
|> 
|> Of course B::fn() hides A::fn(). That is why I wrote it! After all A::fn() 
|> is virtual.

The message means that B::fn hides A::fn() and the compiler is wondering
whether perhaps you want B::fn to override A::fn() instead.  I am not sure
why the message goes away when you reverse 1. and 2.  This may have
something to do with what implicit type conversion gets performed.  If you
want B::fn() to override A::fn() for 1. or 2., you must declare it with
exactly the same prototype.

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Robert Blumen                          | rblumen@tcs.com
Senior Software Engineer               | 2121 Allston Way, Berkeley, CA 94704
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