bug#20146: font-lock-extend-jit-lock-region-after-change: results are discarded instead of being returned.

[Stefan Monnier]

> In font-lock-extend-jit-lock-region-after-change in font-lock.el, the
> new fontification region is calculated by funcalling
> font-lock-extend-after-change-region-function.  The result of this
> funcall is assigned to internal variables beg and end.

> To return these values to the caller, they should be written to the
> dynamically bound variables jit-lock-start and jit-lock-end.  This is
> only done in the case

>     (memq 'font-lock-extend-region-wholelines
>            font-lock-extend-region-functions)

> .  It should be done in all cases.

I'm thinking of removing font-lock-extend-after-change-region-function
altogether anyway: cc-mode is the only user and it has a workaround in
place for when the "feature" is absent, so it's really just useless.


        Stefan