Re: cc-mode fontification feels random

[Stefan Monnier]

> So if the first windowful of a file that's displayed is at EOB,
> fontification must go all the way back to BOB and start scanning
> there, until it comes to the end?

Yup.  The way to make it bearable is to make that scan be as simple and
fast as possible.

Note that `syntax-propertize` and `syntax-ppss` also work this way, so
it's already the case that when we start by displaying EOB we first have
to apply `syntax-propertize` over the whole buffer :-(

In theory, there are various cases (which depend on the specific
programming language under consideration) where we could avoid such
a scan, but it would introduce a lot of complexity so we don't bother.

>> Indeed, there's no way currently for font-lock to tell jit-lock that it
>> has decided to fontify a particular chunk without being requested to do
>> so (Eli suggests setting the `fontified` property, but this means that
>> all the clients of jit-lock have done their work, so it's only correct
>> to set it from font-lock if you run the other `jit-lock-functions` (or
>> if there are currently no other `jit-lock-functions`)),
>
> By "other clients" you mean those which don't fontify, but instead
> piggy-back jit-lock to do other jobs?

`grep jit-lock-register` in Emacs' bundled files gives
bug-reference-mode, glasses-mode, and goto-address-mode as packages
which use jit-lock.


        Stefan