Re: CC Mode troubles and Emacs 29

[Gregory Heytings]

> If this is so, I find it strange that we don't have heaps of bug reports 
> about this in our bug tracker.  I doubt that anyone could ignore the 
> terrible misbehavior you describe, if indeed the description is accurate 
> and not exaggerated.

It's indeed exaggerated, AFAIU.  Basically, it's an effect of the 
c-fontify-new-found-type function, which was added to CC Mode in Oct 2021 
because of this thread: 
https://lists.gnu.org/archive/html/emacs-devel/2021-06/msg00174.html.  A 
simple recipe is this:

emacs -Q
C-x C-f foo.c

and type:

int main () { int foo; foo = 1; }
typedef foo SPC

Now 'foo' in 'foo = 1' is fontified in green, because CC Mode considers 
that 'foo' is a type.  If you now realize that 'foo' is a typo, and that 
what you actually meant is 'foobar', and correct that typo with DEL bar, 
'foo' in 'foo = 1' does not loose its type fontification.  And if you do 
that often enough, in the end the buffer is "filled with green splotches". 
Note that this can easily be fixed with C-u C-x x f C-x x f.

It's actually a nice example of the inherent limits of a fontification 
that is not based on an actual parser.