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

[Khaled Hosny <dr.khaled.hosny@gmail.com>]

On Sat, Dec 22, 2018 at 12:11:15PM +0200, Eli Zaretskii wrote:
> > Date: Sat, 22 Dec 2018 11:06:44 +0200
> > From: Khaled Hosny <dr.khaled.hosny@gmail.com>
> > Cc: Glenn Morris <rgm@gnu.org>, far.nasiri.m@gmail.com, behdad@behdad.org,
> > 	33729@debbugs.gnu.org, kaushal.modi@gmail.com
> > 
> > > Alternatively, we could just use HarfBuzz’s own built in ucdn-based
> > > Unicode function for this. The only reason for overriding this in Emacs
> > > was to keep HarfBuzz and Emacs Unicode support in sync, but if we are
> > > going to duplicate the Unicode script data then better use what HarfBuzz
> > > has.
> > > 
> > > I’m going to try this now.
> > 
> > I pushed a commit to harfbuzz branch that I think fixes this issue now.
> 
> Thanks.
> 
> There's a FIXME in the change you pushed (which I believe just
> repeats what was already in the previous version).  Ca you tell more
> about the problem we need to fix there?

We need a way to get Unicode composition and decomposition for the
a given character (implementing the uni_compose and uni_decompose
functions I deleted). I recall you suggested something earlier that I
tried but couldn’t get to work, the exact detail escapes me.