Re: Git Interactive Rebase - Bug in error message ?

Re: Git Interactive Rebase - Bug in error message ?

[Matthieu Tourne]

Hi,

I tried to perform an interactive rebase of several commits in my tree.
In one of my commits I had performed a git rm --cached, on several files.
The resulting message was :

error: Untracked working tree file 'foo' would be overwritten by merge.
shift: 1: can't shift that many

I eventually removed the file from the fs, and the rebase worked.
The fact that the rebase is not working is probably not a bug, but the
last line looks like an sh bug.

I can reproduce this with git 1.7.1, and also git HEAD (1.7.1.245.g7c42e)


this can be reproduced with :

$ mkdir dirA
$ echo "A" > dirA/A
$ git commit -a -m 'first commit'

$ mkdir dirB
$ echo "B" > dirB/B
$ git commit -a -m 'creating dirB'

$ mkdir dirC
$ echo "C" > dirC/C
$ git rm -r --cached dirA
$ git commit -a -m 'creating dirC, removing dirA'

$ git rebase --interactive HEAD~2
(then swapping the two commits)

pick creating dirC, removing dirA
pick creating dirB

error: Untracked working tree file 'dirA/A' would be overwritten by merge.
shift: 1: can't shift that many


Thank you,

Matthieu.

-- 
Matthieu Tourne

[PATCH] rebase -i: Abort cleanly if new base cannot be checked out

[Ian Ward Comfort]

On 7 Jun 2010, at 5:06 PM, Matthieu Tourne wrote:
> I tried to perform an interactive rebase of several commits in my tree.
> In one of my commits I had performed a git rm --cached, on several files.
> The resulting message was :
>
> error: Untracked working tree file 'foo' would be overwritten by merge.
> shift: 1: can't shift that many
>
> I eventually removed the file from the fs, and the rebase worked.
> The fact that the rebase is not working is probably not a bug, but the
> last line looks like an sh bug.

The last line is a side effect of dash, which apparently complains when asked
to shift from an empty array, and it shouldn't be there. The best fix, though,
isn't to silence shift but to eliminate that code path by fixing another bug
in rebase--interactive. In the scenario you describe, git currently leaves the
repository in the middle of an impossible rebase, with questionably-consistent
state in .git/rebase-merge. The behavior is more compactly (if more
nonsensically) exhibited with:

  $ git init test && cd test
  $ touch A
  $ git add A
  $ git commit -m 'add' A
  $ git rm --cached A
  $ git commit -m 'remove'
  $ GIT_EDITOR=: git rebase -i --no-ff HEAD^

Let's abort cleanly instead, since that's what non-interactive rebase does
already.

---- 8< ----

Untracked content in the working tree may prevent rebase -i from checking out
the new base onto which it wants to replay commits, if the new base commit
includes files at those (now untracked) paths. Currently, rebase -i dies
uncleanly in this situation, updating ORIG_HEAD and leaving a useless
.git/rebase-merge directory, with which the user can do nothing useful except
rebase --abort. Make rebase -i abort the procedure itself instead, as
non-interactive rebase already does, and add a test for this behavior.

Signed-off-by: Ian Ward Comfort <icomfort@stanford.edu>
---
 git-rebase--interactive.sh    |    3 ++-
 t/t3404-rebase-interactive.sh |   10 ++++++++++
 2 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 436b7f5..6b86abc 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -974,8 +974,9 @@ EOF
 
 		test -d "$REWRITTEN" || test -n "$NEVER_FF" || skip_unnecessary_picks
 
+		output git checkout $ONTO || die_abort "could not detach HEAD"
 		git update-ref ORIG_HEAD $HEAD
-		output git checkout $ONTO && do_rest
+		do_rest
 		;;
 	esac
 	shift
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index f20ea38..8d40915 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -146,6 +146,16 @@ test_expect_success 'abort' '
 	! test -d .git/rebase-merge
 '
 
+test_expect_success 'abort with error when new base cannot be checked out' '
+	git rm --cached file1 &&
+	git commit -m "remove file in base" &&
+	test_must_fail git rebase -i master > output 2>&1 &&
+	grep "Untracked working tree file .file1. would be overwritten" \
+		output &&
+	! test -d .git/rebase-merge &&
+	git reset --hard HEAD^
+'
+
 test_expect_success 'retain authorship' '
 	echo A > file7 &&
 	git add file7 &&
-- 
1.7.1