bug#33729: 27.0.50; Partial glyphs not rendered for Gujarati with Harfbuzz enabled (renders fine using m17n)

[Eli Zaretskii]

> Date: Sat, 5 Jan 2019 23:04:20 +0200
> From: Khaled Hosny <dr.khaled.hosny@gmail.com>
> Cc: far.nasiri.m@gmail.com, behdad@behdad.org, 33729@debbugs.gnu.org
> 
> I pushed a couple of commits that does this based on my limited
> understanding of Emacs code, please check.

Can you explain why you moved the call to
hb_buffer_guess_segment_properties _after_ the code which sets some of
the properties?  I cannot find anything about that in the HarfBuzz
documentation.  Is this because guessing the unset properties can
benefit from knowing the properties which _are_ set, such as the
direction?

I did it the other way around, because my mental model was: first set
the defaults, then override them where better info is available.

Thanks.