Re: CC Mode with font-lock-maximum-decoration 2

[Eli Zaretskii]

> Date: Mon, 8 Aug 2022 18:41:01 +0000
> Cc: emacs-devel@gnu.org
> From: Alan Mackenzie <acm@muc.de>
> 
> > And btw, I'm not sure I understand what you are saying.  Are you
> > saying that level 2 is enough for fontifications in C mode?
> 
> No.
> 
> > If so, what are we losing when compared to the value t, and if we don't
> > lose anything important, why do we need any fontifications beyond what
> > level 2 gives us?
> 
> We lose accuracy.  That is important to a lot of people, including the
> many who have sent in bug reports because of lack of accuracy.

Then what is the importance of these measurements of yours?  The fact
that at level 2 C mode is only slightly slower than Lisp mode is
therefore purely academic: you don't expect anyone to use it, and
don't recommend using it.

> > For Lisp, btw, the difference between level 2 and t is negligible.
> > And the same goes for most/all other modes, which is the reason why we
> > have set the value to t years ago.  I'm quite sure at that time the
> > difference between 2 and t for C mode was also very small.
> 
> Martin Stjernholm wrote (what has become) the current level 3 around 20
> years ago, noting specifically it was expected to be slower than before,
> and that the new level 2 was comparable in both speed and accuracy to the
> old level 3.  Since then level 3 has become considerably more accurate
> and quite a bit slower, too.

That's almost certainly what happened.