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bug#39680: 27.0.60; electric-pair-mode broken by undo
From: |
Kévin Le Gouguec |
Subject: |
bug#39680: 27.0.60; electric-pair-mode broken by undo |
Date: |
Wed, 19 Feb 2020 19:34:37 +0100 |
Hello,
Commit e66d5a1c45 (2019-02-19T00:00:44Z!monnier@iro.umontreal.ca) might
have introduced a bug. From emacs -Q:
1. C-x b foo RET
2. M-x electric-pair-mode RET
3. (
- A closing parenthesis has been inserted.
4. C-b C-f
- This is to break undo grouping.
5. a
6. C-_
7. (
In Emacs 26.3, buffer foo contains "(())" and point is after the
innermost opening bracket.
In Emacs 27, buffer foo contains "()" and point is after the closing
bracket. The *Messages* buffer shows:
> cancel-change-group: Undoing to some unrelated state
NB: this can be reproduced with other electric-pair characters, e.g. ".
I found the bug in a Python buffer trying to write a tuple of strings: I
opened a parenthesis, forgot to add quotes, wrote a string, hit undo,
tried to insert a single quote… and got moved past the end parenthesis
instead.
I tried to write a non-regression test; unfortunately what I came up
with does not catch this bug reliably:
(ert-deftest electric-pair-undo-unrelated-state ()
(with-temp-buffer
(buffer-enable-undo)
(electric-pair-mode)
(let ((last-command-event ?\())
(self-insert-command 1))
(undo-boundary)
(insert "hi there")
(undo)
(let ((last-command-event ?\())
(self-insert-command 1))))
C-x C-e'ing the (with-temp-buffer …) form only triggers the error once
every two evaluations, for some reason.
Thank you for your time.
In GNU Emacs 28.0.50 (build 5, x86_64-pc-linux-gnu, GTK+ Version 3.24.13, cairo
version 1.16.0)
of 2020-02-19 built on my-little-tumbleweed
Repository revision: e1e1bd8f85c53fea9f61b6ec99b461ddd93461b9
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12007000
System Description: openSUSE Tumbleweed
Configured using:
'configure --with-xwidgets --with-cairo'
- bug#39680: 27.0.60; electric-pair-mode broken by undo,
Kévin Le Gouguec <=