bug#13446: 24.2; Fix loop test in linum.el

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Any reason why this hasn't been accepted?

On my end, it's mostly for lack of time.  But having just looked at it,
I can't see what the problem is about really.  I mean, your patch looks
fine, but it's not clear what it's fixing.  I've read your explanation,
but I think it's too subtle to explain with only text.

I just installed your patch into trunk, since it looks sane.

But I'd be interested to hear a concrete description of the problematic
behavior this bug could introduce.


        Stefan


> Nathan Trapuzzano <nbtrap@nbtrap.com> writes:

>> There is an incorrect loop test in linum.el that potentially applies an
>> overlay to a line not visible in the window and thereby messes up the
>> width of the overlays in the lines that are visible. The patch/merge
>> directive is attached, and what follows is the commit message:
>> 
>> -----
>> 
>> Modify loop test in `linum-update-window'.
>> 
>> `limit' is set to the position returned by `window-end'; this position
>> is either on the last visible (logical) line in the buffer or is the
>> first position on the line following the last visible line. In the
>> former case, the loop variable never reaches the value of `limit', but
>> in the latter case, an overlay is applied to a line that is not
>> visible in the window. This can mess up the width of the overlay on
>> the visible lines, especially if the width of the line number (as a
>> string) of the line that's not visible is different from the width of
>> the visible lines' line numbers.
>> # Bazaar merge directive format 2 (Bazaar 0.90)
>> # revision_id: nbtrap@nbtrap.com-20130115010121-h7kwjyr5kimowgml
>> # target_branch: .
>> # testament_sha1: a9154d3ede2b389220646bb8e9e708117d876d01
>> # timestamp: 2013-01-14 20:03:26 -0500
>> # base_revision_id: nbtrap@nbtrap.com-20130111013646-pn4xh5r94x5asomb
>> # 
>> # Begin patch
>> === modified file 'lisp/linum.el'
>> --- lisp/linum.el	2012-01-19 07:21:25 +0000
>> +++ lisp/linum.el	2013-01-15 00:45:27 +0000
>> @@ -151,7 +151,7 @@
>> (run-hooks 'linum-before-numbering-hook)
>> ;; Create an overlay (or reuse an existing one) for each
>> ;; line visible in this window, if necessary.
>> -    (while (and (not (eobp)) (<= (point) limit))
>> +    (while (and (not (eobp)) (< (point) limit))
>> (let* ((str (if fmt
>> (propertize (format fmt line) 'face 'linum)
>> (funcall linum-format line)))
>> 
>> # Begin bundle
>> IyBCYXphYXIgcmV2aXNpb24gYnVuZGxlIHY0CiMKQlpoOTFBWSZTWdjgvvgAABJfgAAQQGFxUBIA
>> AACv794QIABkRTaajamQyGjTaRiFGgBMBBkwQhDmaVnH5r9hMFQyJ7EUzThiw4Ixc/mQVpexbPS2
>> 9yLLTxaFbWvXcN2zcydOQxpD652acQC4g4Z96jI5BipgKAAiM5Zz45Kd/4u5IpwoSGxwX3wA