GNU bug report logs - #13796
24.3.50; Minor bug in "(elisp) Managing Overlays"

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Xue Fuqiao <xfq.free <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3.50; Minor bug in "(elisp) Managing Overlays"
Date: Sun, 24 Feb 2013 07:57:58 +0800

In (info "(elisp) Managing Overlays"):

 -- Function: move-overlay overlay start end &optional buffer
[...]
     This is the only valid way to change the endpoints of an overlay.
[...]

 -- Function: remove-overlays &optional start end name value
     This function removes all the overlays between START and END whose
     property NAME has the value VALUE.  It can move the endpoints of
     the overlays in the region, or split them.

I think both `move-overlay' and `remove-overlays' can change the
endpoints of an overlay.  So maybe it is a bug here.



In GNU Emacs 24.3.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.6.0)
 of 2013-02-24 on Emacs
Bzr revision: 111865 rgm <at> gnu.org-20130223220645-ym5xjdm8i09p2huy
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-- 
Best regards, Xue Fuqiao.
http://www.emacswiki.org/emacs/XueFuqiao

Message #8 received at 13796 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: Xue Fuqiao <xfq.free <at> gmail.com>
Cc: 13796 <at> debbugs.gnu.org
Subject: Re: bug#13796: 24.3.50; Minor bug in "(elisp) Managing Overlays"
Date: Sat, 23 Feb 2013 22:35:24 -0500

Xue Fuqiao wrote:

> I think both `move-overlay' and `remove-overlays' can change the
> endpoints of an overlay.  So maybe it is a bug here.

remove-overlays may move them as a side effect. This does not invalidate
the point that

     This is the only valid way to change the endpoints of an overlay.
     Do not try modifying the markers in the overlay by hand, as that
     fails to update other vital data structures and can cause some
     overlays to be "lost".

is trying to make. Anyway, remove-overlays uses move-overlays.

Message #15 received at 13796 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Glenn Morris <rgm <at> gnu.org>
Cc: Xue Fuqiao <xfq.free <at> gmail.com>, 13796 <at> debbugs.gnu.org
Subject: Re: bug#13796: 24.3.50; Minor bug in "(elisp) Managing Overlays"
Date: Sun, 24 Feb 2013 21:10:06 -0500

>      This is the only valid way to change the endpoints of an overlay.
>      Do not try modifying the markers in the overlay by hand, as that
>      fails to update other vital data structures and can cause some
>      overlays to be "lost".

I'm wondering exactly what kind of "modifying the markers in the overlay
by hand" is being referred to here,


        Stefan

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