Re: cc-mode fontification feels random

[Daniel Colascione <dancol@dancol.org>]

On June 9, 2021 11:23:04 AM Alan Mackenzie <acm@muc.de> wrote:

> Hello, Eli.
>
> On Tue, Jun 08, 2021 at 21:25:49 +0300, Eli Zaretskii wrote:
>>> From: Daniel Colascione <dancol@dancol.org>
>>> Date: Tue, 8 Jun 2021 11:11:21 -0700
>>> Cc: rudalics@gmx.at, emacs-devel@gnu.org, rms@gnu.org, acm@muc.de
>
>>> The whole point of fontification is to provide visual hints about
>>> the semantic structure of source code. If cc-mode can't do that
>>> reliably, my preference would be for it to not do it at all.
>>> Fontification of a type-using expression shouldn't change if I move
>>> the definition of that type from one file to another.
>
>> 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.
>
>>> IMHO, we should rely on LSP to figure out what symbols are types, and if
>>> a LSP isn't available, we shouldn't try to guess.
>
> "Shouldn't try to guess" means taking a great deal of
> font-lock-type-faces out of CC Mode.  I don't honestly think the end
> result would be any better than what we have at the moment.


>
I think it would be better in fact. The whole point of fontification is to 
provide visual clues about the function of a word in a buffer. If I can't 
rely on font lock type face actually distinguishing types from non-types, 
what's the point? If fontification isn't reliable, it's not syntax 
highlighting, but instead a kewl rainbow effect.

ISTM we can only correctly do fontification of type references with the 
help of LSP. Without LSP support, I'd rather we not try to get it right, 
sometimes get it wrong, and make font-lock-type-face unreliable.  (We can 
correctly fontify declarations and definitions I think.)