bug#14574: prog-prettify-symbols breaks font-locking

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Mon, 17 Jun 2013 11:22:33 +0200
> 
> On Mon, Jun 17, 2013 at 9:25 AM, Ted Zlatanov <tzz@lifelogs.com> wrote:
> 
> > IIUC, that would be pretty annoying when editing Perl or other languages
> > with Unicode (e.g. Cyrillic) data in the script.
> 
> Not many scripts (relatively speaking) use the kind of character
> variation that needs composition

If you are the user of those particular scripts, removing the
compositions will be rather nasty for you, because it makes the text
barely legible, sometimes not at all.

> (mostly arabic and many indic scripts, but not cyrilic, I think).

Arabic uses automatic compositions, not static compositions produced
by text properties.  If you want to see which scripts use the
'composition' properties, search Lisp files for compose-region.

Perhaps Handa-san could tell if having 'composition' properties in
comments and strings is something that can happen in real life for
some scripts used in those comments/strings.  If it can (and I don't
know one way or the other), then I don't think we should remove all of
the 'composition' properties just because font-lock was turned off.

> we're still a long way from another release, I suppose. Plenty of
> time to receive user complains and implement a more thorough fix,
> IMHO.

You assume that representatives of affected communities track Emacs
development.  But that assumption is not really guaranteed to be true.