Re: C++ binary compatibility between GCC 3.1 and GCC 3.2?

[Andreas Jaeger <aj at suse dot de>]

Mark Mitchell <mark@codesourcery.com> writes:

>> What does this mean for binary compatibility between GCC 3.1 and GCC
>> 3.2?  With the introduction of GCC 3 and its ABI, the expectation by
>> users is that we won't have binary incompatible changes.  Unfortunatly
>> the - AFAIK valid - bug reports show that the ABI implemention was
>> buggy and therefore needed to change.
>
> Yes, the implementation had some bugs.  It was also the case that the
> ABI specification had some bugs/omissions/unclarities.  (The most recent
> substantive change to the ABI specification occurred about a week ago.)
>
> There are getting to be fewer and fewer bugs and the rate of change to
> the ABI is approaching zero, but I, like you, am disappointed that we're
> still breaking the C++ ABI between major releases of the compiler.
>
> In any case, GCC 3.1 and GCC 3.2 will not be 100% binary compatible
> with respect to the C++ ABI.

How severe is this?  Will people encounter this in every day code or
is only in some esoteric situations?

> I can't say what that might mean as a distributor.

Putting on my distributor hat - and answering without much thinking
about all the implications - it would be better to have 3.1.1 and 3.2
compatible (with the cost of 3.1 and 3.1.1 not compatible to each
other).  Alternativly we could rename GCC 3.1.1 to GCC 3.2.1 and
release that in a few weeks time (this would imply to rename mainline
to GCC 3.3 prerelease and have GCC 3.3 release in autumn).

As you see, I haven't made my up mind and do not know what the best
solution is here.

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj