Re: Vtable incompatibility between GCC 3.0/3.2?

[Stephan Bergmann <stephan dot bergmann at sun dot com>]

Hi Andreas.

Thanks for your quick reply and clarification.  With only a change in 
minor (from 3.1 to 3.2), I naively would have assumed that there are no 
incompatible changes, at least no backwards incompatible ones.

Is there any specification of what exactly is guaranteed to work when 
mixing different versions of GCC?  I am mostly interested in scenarios 
of the form "given a (C++) executable built with GCC version X and a 
(C++) shared library built with GCC version Y, is it guaranteed that 
they can be run together and can interoperate?"  (This is the kind of 
question that keeps arising for the component-based OpenOffice.org 
suite.)  I fail to find such information on the GCC web site.

-Stephan


> Stephan Bergmann <stephan.bergmann@sun.com> writes:
>
>
> > Hi all.
> >
> > I just found out the hard way :)  that there is an incompatibility in
> > the vtable layout of GCC 3.0.1 and GCC 3.2.2, see below.  Can anybody
> > confirm whether this is a known issue (a deliberate change?), and
> > between which two GCC versions the change was introduced?  I did not
> > find anything about this in the changes notes.
>
>
> GCC 3.2 is binary incompatible on the C++ level to earlier releases -
> that's one of the reasons why we released it as 3.2.  For details read
> this webpage:
>
> http://gcc.gnu.org/gcc-3.2/changes.html
>
>
>
> Andreas