[Bug c++/11570] New: incorrect behaviour in calling base class methods

["OMS-sero dot Project at ict dot nl" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11570

           Summary: incorrect behaviour in calling base class methods
           Product: gcc
           Version: 3.2.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: OMS-sero dot Project at ict dot nl
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: Cygwin PC with cross compiler
GCC target triplet: PowerPC

Dear mr. G.Nu,

I discovered some incorrect behaviour in calling base class methods inherited by
a derived class object. I enclosed the concerning files with this bug report, 
that
specify the calls. It seems as if the offset to the called method is incorrecty
calculated. This is my situation that consists of three classes:


Menu::keyDownPressed()
{
  // calls
  gMenuLeft->isPresent();
}

class MenuDevice
{
public:
  MenuDevice(){};
  virtual ~MenuDevice(){};

  //virtual bool isPresent() 
  virtual const bool isPresent() const {return true;};
  virtual const sInt getValue(uInt id) const = 0;
};

class MenuLeft : public Menu,
                 public MenuDevice
{
  // forced redefined from base class Menu
  const uInt getCurrentAction();
  // forced redefined from base class MenuDevice
  const sInt getValue(uInt) const;
};


When I call "gMenuLeft->isPresent()" I don't end up in the "isPresent()" call 
belonging
to "gMenuLeft", but in another call, actually the "getCurrentAction()" call. 

Now I change the definition of the "MenuLeft" class to the following. Thus 
change the
order of base class initialisation. Now when I call "gMenuLeft->isPresent()" I 
also end
up in the "gMenuLeft->isPresent()" method. It looks as if the offset to the 
method call is
calculated to the first defined base class, or so...


class MenuLeft : public MenuDevice,
                 public Menu
                 
{
  // forced redefined from base class Menu
  const uInt getCurrentAction();
  // forced redefined from base class MenuDevice
  const sInt getValue(uInt) const;
};


We are using a Cygwin environment, with a GNU GCC cross compiler for a PowerPC 
platform.

With kind regards,
M. Zuidhof
ICT Solution BV
The Netherlands