bug#34035: 26.1; Arabic shadda-kasrah renders incorrectly

[Stephen Berman]

On Sun, 23 Aug 2020 10:15:19 +0300 Eli Zaretskii <eliz@gnu.org> wrote:

>> From: James Cloos <cloos@jhcloos.com>
>> Cc: "Basil L. Contovounesios" <contovob@tcd.ie>,  34035@debbugs.gnu.org,
>>   stefan@marxist.se,  craven@gmx.net
>> Date: Sun, 23 Aug 2020 02:41:09 -0400
>>
>> i bet this is the same as the regression i posted a while back where
>> cr+hb fails to handle fully mono fonts whereas the xft-based code does
>> handle them.
>>
>> i suspect m17n-lib had the necessary code, whereas hb lazily only cares
>> aboutfonts with zero-width accents or with routines *in* each font
>> correctly to combine glyphs.
>
> I don't understand why you consider this a regression.  For the
> shadda-kasrah case, the experts seem to unanimously say that both
> renderings are possible and correct, and which one is used is a
> stylistic preference.

I agree with the latter sentence (and indeed this thread taught me that
both renderings are legitimate), yet it seems unlikely to me that
e.g. the designers of DejaVu Sans and DejaVu Sans Mono deliberately made
this stylistic distinction between these two fonts.  And if not, and if
these two fonts display shadda-kasra combinations the same under
m17n-lib (I cannot test that right now), then that would indeed indicate
a bug in HarfBuzz/Cairo.

Steve Berman