bug#20140: 24.4; M17n shaper output rejected

[Eli Zaretskii]

> Date: Sat, 5 Feb 2022 22:52:51 +0000
> From: Richard Wordingham <richard.wordingham@ntlworld.com>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>, 20140@debbugs.gnu.org
> 
> Sad to see that Khaled Hosny's suggestion not to use composition rules
> seems not to have been taken.

Btw, the _only_ reason Handa-san and now myself were able to implement
something like the forward/backward-char-intrusive commands is that we
DO control which parts of text are composed and which aren't.  If we
were to follow HarfBuzz developers' advice, and were to hand all the
text to HarfBuzz for shaping, we would need the HarfBuzz cooperation
to implement such features in the editor.