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bug#23871: 25.1.50; Undo unexpectedly leads to blank buffer
From: |
Markus Triska |
Subject: |
bug#23871: 25.1.50; Undo unexpectedly leads to blank buffer |
Date: |
Wed, 29 Jun 2016 23:47:19 +0200 |
To reproduce this issue, please perform the following steps:
1. Install SWI-Prolog >= 7.2. I am using 7.3.23 in the following.
2. Copy ediprolog.el to the current directory via:
$ wget https://www.metalevel.at/ediprolog/ediprolog.el
3. Copy ceiled.pl to the current directory via:
$ wget https://www.metalevel.at/ei/ceiled.pl
4. With ediprolog.el and ceiled.pl in the current directory,
start Emacs with:
$ emacs -Q ceiled.pl -fn "Bitstream Vera Sans Mono 15" \
--eval "(load \"$PWD/ediprolog.el\")"
Please see the screenshot for how this looks for me:
https://www.metalevel.at/ei/ceil1.png
5. Press:
M-x ediprolog-dwim RET
This consults the buffer. If everything works as intended, you see
"Buffer consulted." in the message area.
6. Press:
M-g M-g 15 RET
This moves point at the beginning of "%?- time(....)".
7. Press:
M-x ediprolog-dwim RET
This evaluates the Prolog query at point. It only takes a few
milliseconds to produce a very long line that spans several visual
lines.
Please see the screenshot:
https://www.metalevel.at/ei/ceil2.png
8. Press:
C-_
This *undoes* the insertion of text that resulted from step (7).
9. As expected, the insertion is undone, but unexpectedly a completely blank
buffer remains.
Please see the screenshot:
https://www.metalevel.at/ei/ceil3.png
When I press C-p to move to the previous line, the expected part
of the buffer is shown.
Please see the screenshot:
https://www.metalevel.at/ei/ceil4.png
In summary, step 8 leads to 2 problems:
(a) a blank buffer is shown
(b) point position after the undo is not where point was before the insertion.
Please note that #1095 ("Unexpected point position after undo") may be
related: Point after undo is sometimes at an unexpected position.
Thank you for looking into this!
Markus
In GNU Emacs 25.1.50.1 (x86_64-apple-darwin15.5.0, X toolkit, Xaw scroll bars)
of 2016-05-30 built on mt-imac
Repository revision: 190942baeff3f541abf2a937e0fb4d3f9ea104be
Windowing system distributor 'The X.Org Foundation', version 11.0.11502000
Configured using:
'configure --without-ns CFLAGS=-I/opt/local/include
LDFLAGS=-L/opt/local/lib'
Configured features:
XPM JPEG TIFF GIF PNG GSETTINGS NOTIFY ACL GNUTLS LIBXML2 FREETYPE XFT
ZLIB TOOLKIT_SCROLL_BARS LUCID X11
Important settings:
value of $LANG: en_US.UTF-8
locale-coding-system: utf-8-unix
- bug#23871: 25.1.50; Undo unexpectedly leads to blank buffer,
Markus Triska <=