bug#14170: 24.3; linum won't create all overlays after a folding

[Eli Zaretskii]

> Date: Thu, 11 Apr 2013 04:23:13 +0100
> From: E Sabof <esabof@gmail.com>
> Cc: Stefan Monnier <monnier@iro.umontreal.ca>, rgm@gnu.org, 
> 14170@debbugs.gnu.org
> Here it is:
> 
> (defun 14170-mini ()
>   (interactive)
>   (remove-overlays)
>   (let* ((win-end-initial (window-end nil t))
>          (test-ov (make-overlay (point) (+ (point) 1000))))
>     (overlay-put test-ov 'display "...")
>     (cl-assert (not (= win-end-initial (window-end nil t))))
>     ))
> 
> Will fail most of the time.

Thanks.

Actually, I had a hard time making it fail consistently (after I
overcame the initial failure due to cl-assert not being available in
"emacs -Q" ;-), until I found a simple way to make it 100% repeatable:

  (defun 14170-mini ()
    (interactive)
    (remove-overlays)
    (sit-for 0)  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
    (let* ((win-end-initial (window-end nil t))
           (test-ov (make-overlay (point) (+ (point) 1000))))
      (overlay-put test-ov 'display "...")
      (cl-assert (not (= win-end-initial (window-end nil t))))

And that immediately led to the root cause: window-end was thinking
that the display is up to date, while it really wasn't.

Turns out this is a regression introduced in v24.1, while solving bug
#12600.  I think I fixed this (trunk revision 112268) without
reintroducing that bug.

I don't know if this solves the original problem with linum, but if it
doesn't, that's a different problem.

Thanks.

P.S.  Note that the above recipe still predictably fails at EOB, but
this is expected and correct.