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

[Eli Zaretskii <eliz@gnu.org>]

> From: Stephen Berman <stephen.berman@gmx.net>
> Cc: "Peter" <craven@gmx.net>,  34035@debbugs.gnu.org
> Date: Fri, 11 Jan 2019 10:24:45 +0100
> 
> > Thanks.  On my system, this is displayed correctly, with kasrah above
> > the letter.  So I don't think it's Emacs, I think it's the shaping
> > engine you are using.  As you didn't provide the information collected
> > by "M-x report-emacs-bug", I can only guess what is that shaping
> > engine: XFT and libflt, right?  Maybe you could try building the
> > harfbazz branch, which uses HarfBazz for shaping, I'd expect this
> > problem not to exist there.
> 
> I believe the problem is not with the shaping engine but with the font:

The OP did say he tried different fonts, to no avail.  It would be
interesting to know which fonts were those.

> I see the same problem on both builds from current master (with libotf)
> and from the current harfbuzz branch using my default font, DejaVu Sans
> Mono.  But when I switch the font to Symbola, the kasrah is correctly
> displayed between the sin and the shadda, both on master and on
> harfbuzz.  (Nevertheless, on both branches, after switching to Symbola,
> describe-char surprisingly says this:
> 
> Composed with the following character(s) "ِّ" using this font:
>   xft:-PfEd-DejaVu Sans-normal-normal-semicondensed-*-15-*-*-*-*-0-iso10646-1
> 
> Is this expected?)

Please show the entire output of "C-x =" (I presume you invoke it on
the position of sin?).  FWIW, I don't see this here, but in my case
the default Courier New font is used for displaying this text.