bug#56637: 28.1.90; [FR] Allow a way around font-lock-mode being unconditionally disabled in " *hidden*" buffers

[Eli Zaretskii]

> Cc: 56637@debbugs.gnu.org, Ihor Radchenko <yantar92@gmail.com>
> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Sat, 23 Jul 2022 09:53:55 +0200
> 
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
> 
> >> Sorry, it is a typo. I did mean "the fontification *is* using
> >> (font-lock-ensure)".
> >
> > Ah, good, thanks.
> >
> >> We do use `font-lock-ensure', but it does not always produce the same
> >> results with/without font-lock-mode enabled.
> >
> > I'm not completely surprised, because I remember when writing
> > `font-lock-ensure` that there are many corner cases some of which seem
> > very difficult to fix without actually enabling `font-lock-mode`, but we
> > should still strive to be "as close as possible", so ... do you have
> > a bug report with some concrete cases we could try to fix?
> 
> Would it make sense to make `font-lock-ensure' try harder here, and
> (temporarily) force font-lock mode on (even in temporary buffers) if it
> isn't already?

That could be a good alternative, yes.  We could even add a new
optional argument for that, if it makes sense to allow controlling
this behavior.