GNU bug report logs - #60467
30.0.50; primitive-undo: Changes to be undone by function different from announced

Previous Next

Full log

Message #29 received at 60467 <at> debbugs.gnu.org (full text, mbox):

From: Gregory Heytings <gregory <at> heytings.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 60467 <at> debbugs.gnu.org, yantar92 <at> posteo.net,
 Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: Re: bug#60467: 30.0.50; primitive-undo: Changes to be undone by
 function different from announced
Date: Tue, 03 Jan 2023 13:44:01 +0000

[Message part 1 (text/plain, inline)]

>> Patch attached.
>
> Hmm... scary, even if this is intended for the master branch.  Could you 
> at least keep the few comments which were in the original code, and 
> perhaps also add comments explaining all those tricky tests with consp, 
> equality to t and to old-bul, the significance of (car ptr) and (caar 
> ptr), etc.?  This would make the code more maintainer-friendly, as the 
> need to constantly consult the spec of the various undo-list elements 
> (and hope the spec is complete and accurate ;-) would be avoided.
>

Is the attached patch better in that respect?

>
> I'd prefer to fix this in Emacs 29 if feasible, but unless the changes 
> are much simpler and/or more clearly documented, so that it becomes 
> possible to assess their risks, I don't see how that could happen.
>

I don't see how the changes could be made simpler, sorry, but now they are 
documented.  Feel free to ask further questions if something is still 
unclear.

>
> I presume that all the undo tests we have still pass?
>

They do.

>
> If so, how about adding a test for this bug?
>

I'll see if I can do that, but it seems tricky.

[Fix-combine-change-call.patch (text/x-diff, attachment)]

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.