From: "John Cai via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: John Cai <johncai86@gmail.com>, John Cai <johncai86@gmail.com>
Subject: [PATCH] rebase: set REF_HEAD_DETACH in checkout_up_to_date()
Date: Fri, 11 Mar 2022 05:05:44 +0000 [thread overview]
Message-ID: <pull.1226.git.git.1646975144178.gitgitgadget@gmail.com> (raw)
From: John Cai <johncai86@gmail.com>
Fixes a bug whereby rebase updates the deferenced reference HEAD points
to instead of HEAD directly.
If HEAD is on main and if the following is a fast-forward operation,
git rebase $(git rev-parse main) $(git rev-parse topic)
Instead of HEAD being set to $(git rev-parse topic), rebase erroneously
dereferences HEAD and sets main to $(git rev-parse topic). This bug was
reported by Michael McClimon. See [1].
This is happening because on a fast foward with an oid as a <branch>,
update_refs() will only call update_ref() with REF_NO_DEREF if
RESET_HEAD_DETACH is set. This change was made in 176f5d96 (built-in rebase
--autostash: leave the current branch alone if possible,
2018-11-07). In rebase, we are not setting the RESET_HEAD_DETACH flag,
which means that the update_ref() call ends up dereferencing
HEAD and updating it to the oid used as <branch>.
The correct behavior is that git rebase should update HEAD to $(git
rev-parse topic) without dereferencing it.
Fix this bug by adding the RESET_HEAD_DETACH flag in checkout_up_to_date
so that once reset_head() calls update_refs(), it calls update_ref() with
REF_NO_DEREF which updates HEAD directly intead of deferencing it and
updating the branch that HEAD points to.
Also add a test to ensure this behavior.
1. https://lore.kernel.org/git/xmqqsfrpbepd.fsf@gitster.g/
Signed-off-by: John Cai <johncai86@gmail.com>
---
rebase: update HEAD when is an oid
Fixes a bug [1] reported by Michael McClimon where rebase with oids will
erroneously update the branch HEAD points to.
1. https://lore.kernel.org/git/xmqqsfrpbepd.fsf@gitster.g/
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1226%2Fjohn-cai%2Fjc%2Ffix-rebase-oids-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1226/john-cai/jc/fix-rebase-oids-v1
Pull-Request: https://github.com/git/git/pull/1226
builtin/rebase.c | 2 +-
t/t3400-rebase.sh | 21 +++++++++++++++++++++
2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/builtin/rebase.c b/builtin/rebase.c
index b29ad2b65e7..52afeffcc2e 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -828,7 +828,7 @@ static int checkout_up_to_date(struct rebase_options *options)
options->switch_to);
ropts.oid = &options->orig_head;
ropts.branch = options->head_name;
- ropts.flags = RESET_HEAD_RUN_POST_CHECKOUT_HOOK;
+ ropts.flags = RESET_HEAD_RUN_POST_CHECKOUT_HOOK | RESET_HEAD_DETACH;
ropts.head_msg = buf.buf;
if (reset_head(the_repository, &ropts) < 0)
ret = error(_("could not switch to %s"), options->switch_to);
diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index 71b1735e1dd..0b92e78976c 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -437,4 +437,25 @@ test_expect_success 'rebase when inside worktree subdirectory' '
)
'
+test_expect_success 'rebase with oids' '
+ git init main-wt &&
+ (
+ cd main-wt &&
+ >file &&
+ git add file &&
+ git commit -m initial &&
+ git checkout -b side &&
+ echo >>file &&
+ git commit -a -m side &&
+ git checkout main &&
+ git tag hold &&
+ git checkout -B main hold &&
+ git rev-parse main >pre &&
+ git rebase $(git rev-parse main) $(git rev-parse side) &&
+ git rev-parse main >post &&
+ test "$(git rev-parse side)" = "$(cat .git/HEAD)" &&
+ test_cmp pre post
+ )
+'
+
test_done
base-commit: 1a4874565fa3b6668042216189551b98b4dc0b1b
--
gitgitgadget
next reply other threads:[~2022-03-11 5:05 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 5:05 John Cai via GitGitGadget [this message]
2022-03-11 5:33 ` [PATCH] rebase: set REF_HEAD_DETACH in checkout_up_to_date() Junio C Hamano
2022-03-11 5:55 ` Junio C Hamano
2022-03-11 14:14 ` John Cai
2022-03-11 15:05 ` Phillip Wood
2022-03-11 15:28 ` John Cai
2022-03-11 19:42 ` John Cai
2022-03-11 21:31 ` Phillip Wood
2022-03-11 17:24 ` [PATCH v2 0/2] rebase: update HEAD when is an oid John Cai via GitGitGadget
2022-03-11 17:24 ` [PATCH v2 1/2] rebase: use test_commit helper in setup John Cai via GitGitGadget
2022-03-13 7:50 ` Junio C Hamano
2022-03-14 10:52 ` Phillip Wood
2022-03-14 21:47 ` Junio C Hamano
2022-03-11 17:24 ` [PATCH v2 2/2] rebase: set REF_HEAD_DETACH in checkout_up_to_date() John Cai via GitGitGadget
2022-03-13 7:58 ` Junio C Hamano
2022-03-14 10:54 ` Phillip Wood
2022-03-14 14:05 ` Phillip Wood
2022-03-14 14:11 ` John Cai
2022-03-14 14:25 ` Phillip Wood
2022-03-17 3:16 ` [PATCH v3 0/2] rebase: update HEAD when is an oid John Cai via GitGitGadget
2022-03-17 3:16 ` [PATCH v3 1/2] rebase: use test_commit helper in setup John Cai via GitGitGadget
2022-03-17 13:37 ` Ævar Arnfjörð Bjarmason
2022-03-17 3:16 ` [PATCH v3 2/2] rebase: set REF_HEAD_DETACH in checkout_up_to_date() John Cai via GitGitGadget
2022-03-17 13:42 ` Ævar Arnfjörð Bjarmason
2022-03-17 15:34 ` Junio C Hamano
2022-03-17 19:53 ` [PATCH v4 0/3] rebase: update HEAD when is an oid John Cai via GitGitGadget
2022-03-17 19:53 ` [PATCH v4 1/3] rebase: test showing bug in rebase with non-branch John Cai via GitGitGadget
2022-03-17 21:10 ` Junio C Hamano
2022-03-17 21:37 ` Junio C Hamano
2022-03-17 22:44 ` John Cai
2022-03-17 19:53 ` [PATCH v4 2/3] rebase: use test_commit helper in setup John Cai via GitGitGadget
2022-03-18 11:14 ` Phillip Wood
2022-03-18 13:06 ` John Cai
2022-03-17 19:53 ` [PATCH v4 3/3] rebase: set REF_HEAD_DETACH in checkout_up_to_date() John Cai via GitGitGadget
2022-03-17 21:36 ` Junio C Hamano
2022-03-18 0:30 ` John Cai
2022-03-18 13:54 ` [PATCH v5 0/2] rebase: update HEAD when is an oid John Cai via GitGitGadget
2022-03-18 13:54 ` [PATCH v5 1/2] rebase: use test_commit helper in setup John Cai via GitGitGadget
2022-03-18 16:51 ` Junio C Hamano
2022-03-18 13:54 ` [PATCH v5 2/2] rebase: set REF_HEAD_DETACH in checkout_up_to_date() John Cai via GitGitGadget
2022-03-18 16:55 ` [PATCH v5 0/2] rebase: update HEAD when is an oid Junio C Hamano
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