Re: git rebase --root bug

From

PWPhillip Wood <phillip.wood123@gmail.com>

Date

May 12, 2023, 15:18 UTC

Message-ID

<a6c6d3a4-433d-f275-e31c-4eece062722c@gmail.com>

In-Reply-To

<ZF0U6tneDjLfGxf1@nand.local>

Hi Taylor

On 11/05/2023 17:16, Taylor Blau wrote:

> On Thu, May 11, 2023 at 03:21:11PM +0100, Phillip Wood wrote:
>> The cause of the problem is that --root creates an empty commit (known as
>> "squash_onto" in the code) which it uses as the "onto" commit. When it picks
>> the first commit in the todo list the "onto" commit is amended and so is
>> unreachable when the reflog is expired above. I think the best fix would be
>> to stop pretending that we have a real "onto" commit when --root is used
>> without --onto and either store "new root" .git/rebase-merge/onto or not
>> create that file at all.
> 
> Wouldn't it suffice to consider the squash_onto commit as reachable the
> same way we do for `--indexed-objects`?

diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index ff0afad63e..8ac5e2eec6 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -66,6 +66,19 @@ test_expect_success 'setup' '
  SHELL=
  export SHELL

+test_expect_success 'orig-head is not garbage collected' '
+        git checkout --detach &&
+        test_commit --no-tag x &&
+        (
+                set_fake_editor &&
+                FAKE_LINES="1 edit 2" git rebase -i @~2
+        ) &&
+        git reset @^ &&
+        git reflog expire --expire-unreachable=now &&
+        git gc --prune=now &&
+        git rebase --abort
+'
+
  test_expect_success 'rebase --keep-empty' '
          git checkout -b emptybranch primary &&
          git commit --allow-empty -m "empty" &&

I'm not familiar with the gc code, does it use the --indexed-objects 
option of "git rev-list"?

Best Wishes

Phillip