Hi Ben,
On Wed, 21 Aug 2019, Ben Wijen wrote:
> Consider the following scenario:
> git checkout not-the-master
> work work work
> git rebase --autostash upstream master
>
> Here 'rebase --autostash <upstream> <branch>' incorrectly moves the
> active branch (not-the-master) to master (before the rebase).
>
> The expected behavior: (58794775:/git-rebase.sh:526)
> AUTOSTASH=$(git stash create autostash)
> git reset --hard
> git checkout master
> git rebase upstream
> git stash apply $AUTOSTASH
>
> The actual behavior: (6defce2b:/builtin/rebase.c:1062)
> AUTOSTASH=$(git stash create autostash)
> git reset --hard master
> git checkout master
> git rebase upstream
> git stash apply $AUTOSTASH
Interesting. So the only difference is that the original rebase called
`git reset --hard` on the current HEAD, while the new behavior tries to
reset to the branch to which the user wants to switch, right away.
I can see that this would lead to possible problems e.g. if a file had
been added between master and the current branch.
> This commit reinstates the 'legacy script' behavior as introduced with
> 58794775: rebase: implement --[no-]autostash and rebase.autostash
>
> As with this commit the reset must never change the active branch,
> the 'HEAD is now at ...' message has now been removed.
Actually, I am not so sure that I like this change.
Previously, users had a chance to figure out to which revision the
worktree was reset, before switching the branch (because switching the
branch we _do_, via `git checkout master`).
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 670096c065..a928f44941 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -1968,9 +1968,6 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
> state_dir_path("autostash", &options);
> struct child_process stash = CHILD_PROCESS_INIT;
> struct object_id oid;
> - struct commit *head =
> - lookup_commit_reference(the_repository,
> - &options.orig_head);
This should probably be changed to look up `HEAD` instead, then, so that
we can keep the message.
I.e. you probably want to use `get_oid("HEAD", &head_oid)` instead.
> argv_array_pushl(&stash.args,
> "stash", "create", "autostash", NULL);
> @@ -1991,17 +1988,14 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
> options.state_dir);
> write_file(autostash, "%s", oid_to_hex(&oid));
> printf(_("Created autostash: %s\n"), buf.buf);
> - if (reset_head(&head->object.oid, "reset --hard",
> +
> + /*
> + * We might not be on orig_head yet:
> + * Make sure to reset w/o switching branches...
> + */
> + if (reset_head(NULL, "reset --hard",
> NULL, RESET_HEAD_HARD, NULL, NULL) < 0)
> die(_("could not reset --hard"));
> - printf(_("HEAD is now at %s"),
> - find_unique_abbrev(&head->object.oid,
> - DEFAULT_ABBREV));
> - strbuf_reset(&buf);
> - pp_commit_easy(CMIT_FMT_ONELINE, head, &buf);
> - if (buf.len > 0)
> - printf(" %s", buf.buf);
> - putchar('\n');
>
> if (discard_index(the_repository->index) < 0 ||
> repo_read_index(the_repository) < 0)
> diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
> index b8f4d03467..d1352096f2 100755
> --- a/t/t3420-rebase-autostash.sh
> +++ b/t/t3420-rebase-autostash.sh
> @@ -37,7 +37,6 @@ test_expect_success setup '
> create_expected_success_am () {
> cat >expected <<-EOF
> $(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
> - HEAD is now at $(git rev-parse --short feature-branch) third commit
> First, rewinding head to replay your work on top of it...
> Applying: second commit
> Applying: third commit
> @@ -48,7 +47,6 @@ create_expected_success_am () {
> create_expected_success_interactive () {
> q_to_cr >expected <<-EOF
> $(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
> - HEAD is now at $(git rev-parse --short feature-branch) third commit
> Applied autostash.
> Successfully rebased and updated refs/heads/rebased-feature-branch.
> EOF
> @@ -57,7 +55,6 @@ create_expected_success_interactive () {
> create_expected_failure_am () {
> cat >expected <<-EOF
> $(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
> - HEAD is now at $(git rev-parse --short feature-branch) third commit
> First, rewinding head to replay your work on top of it...
> Applying: second commit
> Applying: third commit
> @@ -70,7 +67,6 @@ create_expected_failure_am () {
> create_expected_failure_interactive () {
> cat >expected <<-EOF
> $(grep "^Created autostash: [0-9a-f][0-9a-f]*\$" actual)
> - HEAD is now at $(git rev-parse --short feature-branch) third commit
> Applying autostash resulted in conflicts.
> Your changes are safe in the stash.
> You can run "git stash pop" or "git stash drop" at any time.
> @@ -306,4 +302,16 @@ test_expect_success 'branch is left alone when possible' '
> test unchanged-branch = "$(git rev-parse --abbrev-ref HEAD)"
> '
>
> +test_expect_success 'never change active branch' '
> + git checkout -b upstream unrelated-onto-branch &&
> + test_when_finished "
> + git reset --hard &&
> + git checkout - &&
> + git branch -D upstream" &&
I feel like we want to have a more meaningful branch name than
"upstream", and then we can get away with leaving it in place, i.e. just
test_when_finished "git reset --hard && git checkout -" &&
> + echo changed >file0 &&
> + git add file0 &&
Since `file0` is already tracked, I think that this `git add` invocation
only distracts from the essence of this test case.
> + git rebase --autostash upstream feature-branch &&
> + test_cmp_rev upstream unrelated-onto-branch
Otherwise: well done! And thank you so much for fixing this.
Ciao,
Dscho
> +'
> +
> test_done
> --
> 2.22.0
>
>
