Bug#974139: libpango1.0-dev: PangoFcFont, PangoFcFontMap no longer subclassable

[Marc Lehmann]

On Tue, Nov 10, 2020 at 04:30:07PM +0000, Simon McVittie <smcv at debian.org> wrote:
> On Tue, 10 Nov 2020 at 15:52:26 +0100, Marc Lehmann wrote:
> > If this breakage is indeed intended, maybe debian could simply ship the
> > missing header files (pango/*-private.h)?
> 
> Sorry, I don't think it's appropriate for Debian to be unilaterally
> changing Pango's API. If upstream makes these APIs public again, we can

Actually, upstream has changed both API and ABI unilaterally - the removed
definitions are part of the public ABI, so at some point, debian would
have to bump the .soname.

> pick that up; but if upstream confirms that they're intentionally private,
> making them public again in Debian is just going to cause us more trouble
> in future.

Upstream has now confirmed that it was intentional - apparently, they
don't want people to be able to extend pango themselves anymore, so in the
long term I have to switch to something else anyway.

Now, since these definitions are part of the public ABI, I guess it is
safe to ship these header files myself until actual breakage occurs, but
that's really a bit insane.

The rationale behind debian shipping these headers would be that the
deifntions inside are ABI parameters, so cannot change without a .soname
change, at which point ABI compatibility doesn't matter anymore.

(Pango has broken their ABI in the past without bumping the .soname, so
this is definitely something you should watch out for).

Anyway, thanks for your feedback!

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