Subject: Re: bug#77580: [PATCH] New command ediff-undo

From: Michael Heerdegen <[email-masked]>
Date: Tue, 15 Apr 2025 18:18:43 +0200

Paul Nelson <[email-masked]> writes:

> And (with apologies for the spam) a further, hopefully final update,
> that works in narrowed buffers.

Some comments about your code, independent of how the end result will
look like:

 - Consider to handle an active region similar to how you handle
 narrowing: undo is able to restrict undoing to the region.

 - There is a potential problem with the target buffers of
 `undo-to-buffer': they share the `buffer-file-name' with the original
 buffer.  If they are modified, Emacs will potentially save the contents
 of these buffers to that file, resulting in a mess.

 - Since you mentioned reverting as a use case: doesn't the undo history
 get lost when a buffer is reverted?  I remember that this is the case
 at least sometimes.

Michael.