Bug#522675: libpango1.0-0: pango 1.24 binary incompatible with 1.22

[Sebastian Dröge]

forwarded 522675 http://bugzilla.gnome.org/show_bug.cgi?id=578336

Am Sonntag, den 05.04.2009, 21:22 +0200 schrieb Marc Lehmann:
> Package: libpango1.0-0
> Version: 1.24.0-2
> Severity: normal
> 
> 
> after upgrading to libgpango 1.24, my applications started to crash like
> this:
> 
>    (process:19388): Pango-WARNING **: failed to choose a font, expect ugly output. engine-type='PangoRenderFc', script='latin'
> 
>    (process:19388): Pango-WARNING **: failed to choose a font, expect ugly output. engine-type='PangoRenderFc', script='common'
> 
>    (process:19388): Pango-WARNING **: failed to choose a font, expect ugly output. engine-type='PangoRenderFc', script='hiragana'
>    ./deliantra: line 6: 19388 Segmentation fault      (core dumped)
> 
> The reason is coimmit 9305b9a9995e84ace3818a90346820ef8c47a3ce to pango:
> 
>     [pangofc] Add a "fontmap" property to PangoFcFont
> 
>    Gecko uses its own PangoFcFontMap subclass with its own
>    PangoFontSet.  Previously we were setting font->fontmap in our
>    own private PangoFcFontSet.  Now it's up to the PangoFcFont
>    subclass to set it when creating the new font object.
> 
> applications subclassing the public pangofc api that did work properly
> will now fail. The problem is that doing what the patch suggests works
> with 1.24, but fails with 1.22:
> 
>    Pango:ERROR:/tmp/buildd/pango1.0-1.22.4/pango/pangofc-fontmap.c:559:pango_fc_font_map_add: assertion failed: (fcfont->fontmap == NULL)
> 
> So, while adding:
> 
>    #if PANGO_VERSION_CHECK (1, 23, 1)
>      PANGO_FC_FONT (font)->fontmap = fontmap;
>    #endif
> 
> makes the program work, you need a recompile betwene 1.22 and 1.24, as
> 1.22 checks that the fontmap is 0, and 1.24 requires it to be non-null.
> 
> This makes it hard (nothing short of a run-time check possible) to create
> binaries that work with 1.22 and 1.24.
> 
> (My understanding of this might be wrong, but such a big incompatible
> api change deserves at leats a better error message, especially when
> older versions of pango explicitly made setting the fontmap illegal by an
> assertions).

Thanks, I've forwarded this bug upstream. Let's see what they say about
it... it'd be really bad if there was such an ABI breakage in 1.24.
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