bug#16526: 24.3.50; scroll-conservatively & c-mode regression

[martin rudalics]

>> How should I know?  I suppose redisplay_window eventually winds up
>> calling the fontification function and sooner or later the c-code calls
>> back_comment.
>
> Yes, that's what happens.  And it cannot be avoided, AFAICS, when
> scroll-conservatively is on.

Well ... so you know why it calls back_comment around the END of the
buffer?

> What I see is that find_defun_start is called many times,

... 530 times as I mentioned earlier ...

> with its
> first argument moving from _end_ of the buffer backwards.

Not monotonously.  Sometimes it's called from the same position (for
example 948653 is at least three times on my list) again.

> This
> happens when Emacs needs to redisplay the last portion of the buffer,
> immediately after the call to end-of-buffer.

Hmm ... but the problem is when going to BOB.

> JIT Lock is triggered also when font-lock is turned on after the move
> to end of the buffer.  But the difference seems to come from the fact
> that under scroll-conservatively, we examine the buffer a little bit
> above/below the window, when we decide where to put window-start.

And somehow a "current position" is still near the end of the buffer at
that time.

martin