Re: cc-mode fontification feels random

[Daniel Colascione]

On June 9, 2021 11:37:17 AM Eli Zaretskii <eliz@gnu.org> wrote:

> > Date: Wed, 9 Jun 2021 18:22:57 +0000
> > Cc: Daniel Colascione <dancol@dancol.org>, monnier@iro.umontreal.ca,
> > rudalics@gmx.at, emacs-devel@gnu.org, rms@gnu.org
> > From: Alan Mackenzie <acm@muc.de>
> >
> > > I think we agree.  Except that for me, it should also not try if it
> > > cannot do it quickly enough, not only reliably enough.
> >
> > Quickly and reliably enough are desirable things, but in competition
> > with eachother.  Reliably enough is a lot easier to measure, quickly
> > enough depends on the machine, the degree of optimisation, and above
> > all, the user's expectations.
>
> That's why we had (and still have) font-lock-maximum-decoration: so
> that users could control the tradeoff.  Unfortunately, support for
> that variable is all but absent nowadays, because of the widespread
> mistaken assumption that font-lock is fast enough in all modes.

It should be fast enough for all modes. This isn't 1985. Computers in 
general are *several orders* of magnitude faster than needed to do real 
time syntax highlighting in general. Other editors don't seem to struggle.  
Tree sitter is very fast. If regular editing is stuttering because of 
fontification, we have bad data structures, algorithms, or architectures 
--- that is, bugs. And we shouldn't add user options to paper over bugs. 
That's ridiculous. I can't believe we really want to propose a "please make 
syntax highlighting wrong" user option.