Re: [ft-devel] Re: FreeType issues

[Owen Taylor]

On Sun, 2006-01-22 at 03:57 -0800, Steve Langasek wrote:
> Hi Werner,
> 
> On Sun, Jan 22, 2006 at 09:12:46AM +0100, Werner LEMBERG wrote:
> 
> > I've read your very interesting mail at
> 
> >   http://lists.debian.org/debian-devel-announce/2005/11/msg00016.html
> 
> > What's your recommendation in the light of
> 
> >   http://freetype.org/freetype2/freetype-2.2.0.html
> 
> Thanks for writing!  I applaud the FreeType developers for making this
> effort to clean up the exported interface of the library.  I know that
> proper handling of library ABIs has been an evolutionary process for most of
> us in the Free Software community, and by switching to -export-symbols,
> you guys appear to be ahead of the curve.
> 
> At the same time, I'm dismayed that this page talks about how badly people's
> desktops are going to break, and *not* about a library soname change; and
> there's no indication that the -version-info "age" argument has been reset
> in freetype2 cvs; even though the -export-symbols change is being made
> *explicitly because you know people have been using private interfaces*.

The issue that a soname changed as been mentioned elsewhere in this
thread. If the FreeType soname is changed and you provide both
libfreetype6 and libfreetype7 for Debian (as is the normal practice),
then most of the 583 packages you've identified will be linking 
against *both* libfreetype6 and libfreetype7 until they are rebuilt,
because one of their dependent libraries (fontconfig, libgd, pango,
whatever), links against the new freetype.

The only thing that is predictable about what that will cause is that
it is bad.

If you made libfreetype7 conflict with libfreetype6, then the you
wouldn't have that problem, and you'd just have a massive rebuild
job. 

For this reason, it is less of an issue for distributions that
don't provide compat packages ... a soname change just causes a big
rebuild that is pointless for 98% of all packages and catches the
2% that have problems. (That 2% is pretty well known, however.)

But beyond the world of nicely managed systems and distributions,
there are a whole lot of systems with random libfreetypes floating
around in one directory or another, which will also be subject
to the two-versions problem.

It's not a pretty situation either way ... but a soname change isn't
a magic fix here.

Regards,
                                                Owen