From: Junio C Hamano <gitster@pobox•com>
To: git@vger•kernel.org
Cc: "Christian Couder" <christian.couder@gmail•com>,
"SZEDER Gábor" <szeder@ira•uka.de>
Subject: BUG: "cherry-pick A..B || git reset --hard OTHER"
Date: Tue, 06 Dec 2016 10:58:42 -0800 [thread overview]
Message-ID: <xmqqlgvs28bh.fsf@gitster.mtv.corp.google.com> (raw)
I was burned a few times with this in the past few years, but it did
not irritate me often enough that I didn't write it down. But I
think this is serious enough that deserves attention from those who
were involved.
A short reproduction recipe, using objects from git.git that are
publicly available and stable, shows how bad it is.
$ git checkout v2.9.3^0
$ git cherry-pick 0582a34f52..a94bb68397
... see conflict, decide to give up backporting to
... such an old fork point.
... the git-prompt gives "|CHERRY-PICKING" correctly.
$ git reset --hard v2.10.2^0
... the git-prompt no longer says "|CHERRY-PICKING"
$ edit && git commit -m "prelim work for backporting"
[detached HEAD cc5a6a9219] prelim work for backporting
$ git cherry-pick 0582a34f52..a94bb68397
error: a cherry-pick or revert is already in progress
hint: try "git cherry-pick (--continue | --quit | --abort)"
fatal: cherry-pick failed
$ git cherry-pick --abort
... we come back to v2.9.3^0, losing the new commit!
The above shows two bugs.
(1) The third invocation of "cherry-pick" with "--abort" to get rid
of the state from the unfinished cherry-pick we did previously
is necessary, but the command does not notice that we resetted
to a new branch AND we even did some other work there. This
loses end-user's work.
"git cherry-pick --abort" should learn from "git am --abort"
that has an extra safety to deal with the above workflow. The
state from the unfinished "am" is removed, but the head is not
rewound to avoid losing end-user's work.
You can try by replacing two instances of
$ git cherry-pick 0582a34f52..a94bb68397
with
$ git format-patch --stdout 0582a34f52..a94bb68397 | git am
in the above sequence, and conclude with "git am--abort" to see
how much more pleasant and safe "git am --abort" is.
(2) The bug in "cherry-pick --abort" is made worse because the
git-completion script seems to be unaware of $GIT_DIR/sequencer
and stops saying "|CHERRY-PICKING" after the step to switch to
a different state with "git reset --hard v2.10.2^0". If the
prompt showed it after "git reset", the end user would have
thought twice before starting the "prelim work".
Thanks.
next reply other threads:[~2016-12-06 18:58 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-06 18:58 Junio C Hamano [this message]
2016-12-07 14:31 ` BUG: "cherry-pick A..B || git reset --hard OTHER" Christian Couder
2016-12-07 18:36 ` Stephan Beyer
2016-12-07 20:04 ` Junio C Hamano
2016-12-07 20:35 ` Stephan Beyer
2016-12-07 23:21 ` Duy Nguyen
2016-12-09 11:33 ` Duy Nguyen
2016-12-09 11:34 ` [PATCH] rebase: rename --forget to be consistent with sequencer Nguyễn Thái Ngọc Duy
2016-12-09 11:34 ` [PATCH] revert, cherry-pick: rename --quit to be consistent with rebase Nguyễn Thái Ngọc Duy
2016-12-09 18:07 ` BUG: "cherry-pick A..B || git reset --hard OTHER" Junio C Hamano
2016-12-09 19:24 ` Stephan Beyer
2016-12-09 19:28 ` Stephan Beyer
2016-12-10 11:00 ` Duy Nguyen
2016-12-10 21:23 ` Junio C Hamano
2016-12-08 7:50 ` Christian Couder
2016-12-07 21:51 ` [PATCH 1/5] am: Fix filename in safe_to_abort() error message Stephan Beyer
2016-12-08 10:21 ` Paul Tan
2016-12-07 21:51 ` [PATCH 2/5] am: Change safe_to_abort()'s not rewinding error into a warning Stephan Beyer
2016-12-07 21:51 ` [PATCH 3/5] Add test that cherry-pick --abort does not unsafely change HEAD Stephan Beyer
2016-12-07 21:51 ` [PATCH 4/5] Make sequencer abort safer Stephan Beyer
2016-12-08 15:28 ` Johannes Schindelin
2016-12-08 17:27 ` Junio C Hamano
2016-12-08 19:17 ` Stephan Beyer
2016-12-09 18:33 ` Junio C Hamano
2016-12-09 19:01 ` [PATCH v2 1/5] am: Fix filename in safe_to_abort() error message Stephan Beyer
2016-12-09 19:01 ` [PATCH v2 2/5] am: Change safe_to_abort()'s not rewinding error into a warning Stephan Beyer
2016-12-09 19:01 ` [PATCH v2 3/5] Add test that cherry-pick --abort does not unsafely change HEAD Stephan Beyer
2016-12-09 19:01 ` [PATCH v2 4/5] Make sequencer abort safer Stephan Beyer
2016-12-10 19:56 ` Christian Couder
2016-12-10 20:04 ` Jeff King
2016-12-10 20:20 ` Stephan Beyer
2016-12-09 19:01 ` [PATCH v2 5/5] sequencer: Remove useless get_dir() function Stephan Beyer
2016-12-07 21:51 ` [PATCH " Stephan Beyer
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