Subject: bug#16377: Undo Tree regression: (error "Unrecognized entry in undo list undo-tree-canary")

From: Toby Cubitt <[email-masked]>
Date: Thu, 6 Jul 2017 10:47:39 +0100

On Thu, Jul 06, 2017 at 10:02:56AM +0100, Toby Cubitt wrote:
> I'm way behind on dealing with undo-tree bug reports whilst busy with
> "real life". #16377 is a very helpful bug report, which I can now
> reproduce much more reliably with current Emacs version than I could when
> it was originally reported. I hope to have time for a mammoth undo-tree
> maintenance session later this summer. If that works out, I'll look into
> it then.

Scratch that. I can't reproduce #16377 in Emacs 25.2.1, undo-tree git
head, except by calling undo-tree-undo/redo commands via M-x in buffers
where undo-tree-mode is disabled.

Calling undo-tree commands with undo-tree-mode disabled is entirely
expected to mess up buffer-undo-list. I've added checks in git to all the
undo-tree interactive commands to throw a user-error if they're called
when undo-tree is not enabled, to guard against this.

But that has nothing to do with the original bug, which appears to
already be fixed in git.

Toby
-- 
Dr T. S. Cubitt
Royal Society University Research Fellow
Quantum Information Theory
Department of Computer Science
University College London

email: [email-masked]
web:   www.dr-qubit.org