From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <archer-return-1693-listarch-archer=sourceware.org@sourceware.org>
Received: (qmail 23107 invoked by alias); 27 Sep 2009 18:26:15 -0000
Mailing-List: contact archer-help@sourceware.org; run by ezmlm
Sender: <archer@sourceware.org>
Precedence: bulk
List-Post: <mailto:archer@sourceware.org>
List-Help: <mailto:archer-help@sourceware.org>
List-Subscribe: <mailto:archer-subscribe@sourceware.org>
List-Id: <archer.sourceware.org>
Received: (qmail 23092 invoked by uid 22791); 27 Sep 2009 18:26:14 -0000
X-SWARE-Spam-Status: No, hits=-2.4 required=5.0
	tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS
X-Spam-Check-By: sourceware.org
Date: Sun, 27 Sep 2009 18:26:00 -0000
From: Jan Kratochvil <jan.kratochvil@redhat.com>
To: Keith Seitz <keiths@redhat.com>
Cc: archer@sourceware.org
Subject: Re: set print objct pros/cons  [Re: [Keith Seitz] Re: [tools-team]
 Status 2008-09-01]
Message-ID: <20090927182601.GA10613@host0.dyn.jankratochvil.net>
References: <6d1764b50909230708l60a4be26ocf3bf6aef198710@mail.gmail.com>
 <m3ocoyyik3.fsf@fleche.redhat.com>
 <6d1764b50909251238i6471fcacreea5cfbab57cdd2d@mail.gmail.com>
 <m3iqf6wy7a.fsf@fleche.redhat.com>
 <20090927122147.GA15789@host0.dyn.jankratochvil.net>
 <4ABF9D6E.8020606@redhat.com>
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="uAKRQypu60I7Lcqm"
Content-Disposition: inline
In-Reply-To: <4ABF9D6E.8020606@redhat.com>
User-Agent: Mutt/1.5.20 (2009-08-17)
X-SW-Source: 2009-q3/txt/msg00259.txt.bz2


--uAKRQypu60I7Lcqm
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-length: 1383

On Sun, 27 Sep 2009 19:14:22 +0200, Keith Seitz wrote:
> On 09/27/2009 05:21 AM, Jan Kratochvil wrote:
> >
> >(1) Last "call basep->m ()" should have printed "derived::m"
> >     because "p basep->m" prints "Derived::m()", shouldn't it?
> >
> 
> basep->m will always print "base::m" -- your test case did not
> declare Base::m virtual. Or is that just an omission in the file you
> attached?

It was intentional that way (unaware how common it is in C++ to override
non-virtual method name by a virtual one, though).

I think the following two commands should deal with the same pointer, whithout
even talking about which pointer ("Derived::m" or "Base::m") it should be:

It does not work now - with the previous testcase cxxinherit.C:
	(gdb) set print object on
	(gdb) p basep->m
	$4 = {void (Derived *)} 0x4006c4 <Derived::m()>
	(gdb) call basep->m ()
	base::m


> IMO, "object print" should not even exist at all.

Currently the "off" mode does not work right for the virtual/virtual case:

With the new attached testcase cxxinherit2.C:
	Starting program: /home/jkratoch/t/cxxinherit2 
	derived::m
	derived::m
	Breakpoint 1, main () at cxxinherit2.C:27
	27	  return 0;
	(gdb) show print object 
	Printing of object's derived type based on vtable info is off.
	(gdb) call basep->m ()
	derived::m
	(gdb) p basep->m
	$1 = {void (Base *)} 0x4006a6 <Base::m()>
	(gdb) 


Regards,
Jan

--uAKRQypu60I7Lcqm
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline; filename="cxxinherit2.C"
Content-length: 404

#include <stdio.h>

class Base
  {
  public:
    virtual void m () { puts ("base::m"); }
    virtual void stub () {}
  };

class Derived : public Base
  {
  public:
    virtual void m () { puts ("derived::m"); }
    virtual void stub () {}
  };

int
main ()
{
  Derived derived_local;
  Derived *derivedp = &derived_local;
  Base *basep = &derived_local;

  derivedp->m ();
  basep->m ();

  return 0;
}

--uAKRQypu60I7Lcqm--