bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly

[Eli Zaretskii]

> From: Rah Guzar <aikrahguzar@gmail.com>
> Date: Sat, 2 Oct 2021 14:47:37 +0200
> Cc: 50951@debbugs.gnu.org
> 
> On Sat, Oct 2, 2021 at 2:18 PM Eli Zaretskii <eliz@gnu.org> wrote:
> 
>  What font displays them individually?  You should be able to tell that
>  if you type "C-u C-x =" on one of these characters.
> 
> This is the default font that `emacs -Q` chooses. Using "C-u C-x =" I see,
> 
> ftcrhb:-PfEd-DejaVu Sans-normal-normal-normal-*-13-*-*-*-*-0-iso10646-1 
> (#x56F)

I guess that font is problematic (in more than one way).

>  So would it be correct to say that using a proper font solves the
>  problem?
> 
> This is almost correct except that the font (NotoNastaliqUrdu) that causes 
> problems with emacs
> works fine in libreoffice and both use harfbuzz.

The way to investigate such problems is to see what does hb-view, a
program that is part of the HarfBuzz installation, produce for the
same text with the same font.  If hb-view produces correct display,
but Emacs doesn't, then the problem is indeed in Emacs; otherwise the
problem is probably with the font, and in any case should be taken up
with the HarfBuzz developers.

(Are you sure that LibreOffice uses NotoNastaliqUrdu for the text you
type there?  They could use a different font under the hood.)