Re: New optimisations for long raw strings in C++ Mode.

[Gregory Heytings <gregory@heytings.org>]

>>> But opening the resulting file with "emacs -Q" and then doing a `M->' 
>>> now hangs Emacs, which it didn't use to do, I think?
>>
>> If you do (setq long-line-threshold nil), M-> is fast.  Only when you 
>> omit it does Emacs hang.  Hmm.  It's meant to be the other way around, 
>> isn't it?  ;-)
>
> Yes.  I'm guessing there's some additional bug there.
>

As has been discussed, CC Mode is, sadly, by design, incompatible with the 
new feature (and I wonder what the ";-)" above is supposed to convey). 
It insists on accessing the whole buffer, and doesn't downgrade gracefully 
when it can't.  In this case, with emacs -Q, after M->, 
(jit-lock-fontify-now 999600 1001100) is called, which calls 
(c-font-lock-fontify-region 999600 1000034), which does (widen), and calls 
(font-lock-default-fontify-region 991200 1000034) because these (991200 
and 1000034) are the bounds of the locked narrowing.  For some reason 
(which I don't have the patience to track down), because that (widen), 
which shouldn't be there in the first place, doesn't do what the function 
expects it to do, font-lock-default-fontify-region never ends.