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

[Juanma Barranquero <lekktu@gmail.com>]

On Mon, Jun 17, 2013 at 5:00 PM, Eli Zaretskii <eliz@gnu.org> wrote:

> 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.

Ethiopic, indian languages, Lao, Thai, Tibetan and Tai languages, currently.

> 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.

I don't disagree (or at least, not strongly), but I think is an
unlikely problem because, as I said, the set of conditions under which
can happen is not that big. Currently only Perl (but not Cperl),
(e)lisp and CFEngine buffers will be affected, and only if the user
choses to enable prettification, which is off by default. And then
s/he would have to need to turn off font-locking, which I don't think
it is really a common operation while editing code, is it? So it seems
to me like we have a two line fix for 95% of use cases (were 95% is a
number just invented out of thin air, but you catch my meaning), where
covering 100% of cases is likely to be much more complex.

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

No, I'm assuming that we usually go for fixing real problems versus
perceived ones. Even if we are mistaken and the affected communities
discover after the fact, is not like there are no workarounds or we
cannot implement a 100% fix later.

But don't take that as that I'm opposing a better fix. I'm not. I just
don't see the point yet.

   J