[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14
From: |
Phillip Lord |
Subject: |
bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14 |
Date: |
Sat, 14 May 2016 14:57:02 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.93 (gnu/linux) |
Eli Zaretskii <eliz@gnu.org> writes:
>> Date: Sat, 14 May 2016 12:25:13 +0300
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: 22295@debbugs.gnu.org, Jim Meyering <jim@meyering.net>
>>
>> > From: Jim Meyering <jim@meyering.net>
>> > Date: Sat, 2 Jan 2016 20:01:36 -0800
>> >
>> > Hello,
>> > I noticed that viper-mode's "undo" ('u') command began to undo too much
>> > and was able quickly to determine that it worked fine with my snapshot
>> > built from git master some time on Nov 10, yet that it began to undo
>> > too much four days later.
>> >
>> > To demonstrate the problem (without risking changing anything in your
>> > home directory), run this:
>> >
>> > mkdir /tmp/x && HOME=/tmp/x emacs -Q -f viper-mode -nw
>> > ~/previously-nonexistent-file
>> >
>> > then respond "y", "y", "5" to get past the "viperize" setup questions.
>> > To reproduce the error, insert two lines, terminating each "insertion"
>> > with ESC,
>> > so that each is recorded as a separate undo'able operation. I.e., type this
>> >
>> > a 1 ESC
>> >
>> > to create the first line, then
>> >
>> > o 2 ESC
>> >
>> > to create the second.
>> > Finally, hit "u" to undo creation of the second and you'll see that it
>> > undoes
>> > both operations, erasing both lines. This is rather disruptive when that
>> > first
>> > bit of text was a long paragraph or two -- the novice may think that it's
>> > lost,
>> > because redo does not restore it -- however, it is available in emacs's
>> > yank buffer.
>>
>> Phillip, could you please look into this? This sounds like a annoying
>> problem for users of viper-mode, and AFAIU it happens on the release
>> branch as well.
>
> (Adding Michael to the addressees.)
>
> I took a short look, and it sounds like we need more experts here.
> Undo in viper has its own implementation, which tries to do something
> that is not immediately clear to me, and is not really documented
> anywhere. I guess vi users will know that, but I'm not one of them.
>
> The viper-undo command and related functions manipulate the Emacs undo
> data structures directly, see viper-adjust-undo. I guess the recent
> changes in low-level undo implementation run afoul of what viper-mode
> tries to do.
>
> I hope the above provides enough hints to find the reason for this
> problem and solve it.
>
Sorry for slow response -- was travelling.
Yep, viper is doing strange things to undo -- it adds a symbol ('viper)
to the undo list, then removes it later, amalgamating everything upto
'viper.
I've got a complete test case (below in case anyone is interested --
I'll make a proper unit test of it on master eventually).
On e0f64e7b4f9c3bbc12c4909ca8c8aa751f1fca4a (a random commit around
the time of the error). This produced a undo list like so:
(nil
(2 . 4)
nil
(2 . 3)
(1 . 2)
(t . -1))
While on emacs-25 it gives (my comments):
((3 . 4) ;; insertion from 3 to 4
(2 . 3) ;; insertion from 2 to 3
nil ;; boundary
(2 . 3) ;; insertion from 2 to 3
(1 . 2) ;; insertion from 1 to 2
(t . -1) ;; buffer created with file that does not exist
)
So it looks like the amalgamation that Emacs is supposed to be doing is
failing. No idea at all where the head "nil" has gone.
Will work on this more.
(setq viper-inhibit-startup-message 't)
(setq viper-expert-level '5)
(find-file "/tmp/file.txt")
(setq viper-mode t)
(require 'viper)
;; leave emacs lisp in Emacs mode or edebug becomes impossible
(setq viper-vi-state-mode-list (delq
'emacs-lisp-mode
viper-vi-state-mode-list))
(setq viper-emacs-state-mode-list (cons
'emacs-lisp-mode
viper-vi-state-mode-list))
;; alas edebug "print last eval" is still broken
(require 'edebug)
(edebug-instrument-function 'viper-adjust-undo)
;; a 1
(execute-kbd-macro
[?a ?1 escape ?o ?2 escape])
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Eli Zaretskii, 2016/05/14
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Eli Zaretskii, 2016/05/14
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14,
Phillip Lord <=
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Michael Kifer, 2016/05/14
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Phillip Lord, 2016/05/14
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Michael Kifer, 2016/05/14
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Phillip Lord, 2016/05/16
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Michael Kifer, 2016/05/16
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Phillip Lord, 2016/05/17
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Michael Kifer, 2016/05/17
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Michael Albinus, 2016/05/16
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Phillip Lord, 2016/05/16
- bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14, Michael Kifer, 2016/05/16