Re: [ANNOUNCE] Git v2.26.0-rc1

[Elijah Newren <newren@gmail.com>]

On Tue, Mar 10, 2020 at 12:08 PM Junio C Hamano <gitster@pobox.com> wrote:
>
> Jeff King <peff@peff.net> writes:
>
> > On Tue, Mar 10, 2020 at 07:57:11AM -0700, Junio C Hamano wrote:
> >
> >>  * "git rebase" has learned to use the merge backend (i.e. the
> >>    machinery that drives "rebase -i") by default, while allowing
> >>    "--apply" option to use the "apply" backend (e.g. the moral
> >>    equivalent of "format-patch piped to am").  The rebase.backend
> >>    configuration variable can be set to customize.
> >
> > I noticed a few behavior changes that I think are related to this
> > switch.
> > ...
> > Oops. If I "git rebase --continue" from there, I get "No rebase in
> > progress?". Doing "git cherry-pick --skip" clears it. I guess the issue
> > is the continued presence of .git/CHERRY_PICK_HEAD.
> >
> > As you can see from the output above (and the earlier snippet, if you
> > run it), there are also a bunch of minor stderr output changes. I think
> > these probably aren't worth caring about.
>
> Hmph.  It might have been way premature to switch the default, then.

Or perhaps a bit late in the cycle to do it, yeah.

> Introducing rebase.backend to allow adventurous to opt in early,
> while keeping the default backend same, may not be a bad way to
> avoid the regression in the upcoming release and to give us enough
> time deal with it after the release, perhaps?

Seems reasonable.

> -- >8 --
> Subject: rebase: do not switch the default to 'merge' just yet
>
> Reverts 2ac0d627 (rebase: change the default backend from "am" to
> "merge", 2020-02-15) to postpone the switch of default backend of
> "git rebase" to the merge backend, as there seem to be a few
> remaining bugs (we saw two reported on the day after 2.26-rc1---we
> do not know how many remaining bugs there are) that regresses the
> end user experience.
>
>  * When a rebase stops with a merge conflict, "rebase --continue"
>    after resolving the conflict opens an editor with the merge
>    backend;
>
>  * When a rebase sees a change that is already applied, the end user
>    gets thrown into "cherry-picking" mode, causing "git status" to
>    say "nothing to commit, working tree clean". At that point, "git
>    rebase --continue" does not let the user get out of this state.
>
> Let's keep the default for the upcoming release, without removing
> the configuration variable so that those adventurous can opt into
> using the 'merge' backend to help polishing it.
>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  Documentation/git-rebase.txt           | 6 +++---
>  builtin/rebase.c                       | 4 ++--
>  t/t5520-pull.sh                        | 7 +++----
>  t/t9106-git-svn-commit-diff-clobber.sh | 3 +--
>  4 files changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
> index 8c1f4b8268..58bc556142 100644
> --- a/Documentation/git-rebase.txt
> +++ b/Documentation/git-rebase.txt
> @@ -260,8 +260,7 @@ See also INCOMPATIBLE OPTIONS below.
>
>  --apply:
>         Use applying strategies to rebase (calling `git-am`
> -       internally).  This option may become a no-op in the future
> -       once the merge backend handles everything the apply one does.
> +       internally).  This is the default.
>  +
>  See also INCOMPATIBLE OPTIONS below.
>
> @@ -315,7 +314,8 @@ See also INCOMPATIBLE OPTIONS below.
>  --merge::
>         Use merging strategies to rebase.  When the recursive (default) merge
>         strategy is used, this allows rebase to be aware of renames on the
> -       upstream side.  This is the default.
> +       upstream side.  This may become the default in the future
> +       once known bugs are shaken out of this backend.
>  +
>  Note that a rebase merge works by replaying each commit from the working
>  branch on top of the <upstream> branch.  Because of this, when a merge
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index f3036f40c6..37d2920620 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -100,7 +100,7 @@ struct rebase_options {
>  #define REBASE_OPTIONS_INIT {                          \
>                 .type = REBASE_UNSPECIFIED,             \
>                 .empty = EMPTY_UNSPECIFIED,             \
> -               .default_backend = "merge",             \
> +               .default_backend = "apply",             \
>                 .flags = REBASE_NO_QUIET,               \
>                 .git_am_opts = ARGV_ARRAY_INIT,         \
>                 .git_format_patch_opt = STRBUF_INIT     \
> @@ -1913,7 +1913,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>
>         if (options.type == REBASE_UNSPECIFIED) {
>                 if (!strcmp(options.default_backend, "merge"))
> -                       imply_merge(&options, "--merge");
> +                       options.type = REBASE_MERGE;
>                 else if (!strcmp(options.default_backend, "apply"))
>                         options.type = REBASE_APPLY;
>                 else
> diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
> index 2f86fca042..e8d28e5e36 100755
> --- a/t/t5520-pull.sh
> +++ b/t/t5520-pull.sh
> @@ -340,7 +340,7 @@ test_expect_success '--rebase with conflicts shows advice' '
>         test_tick &&
>         git commit -m "Create conflict" seq.txt &&
>         test_must_fail git pull --rebase . seq 2>err >out &&
> -       test_i18ngrep "Resolve all conflicts manually" err
> +       test_i18ngrep "Resolve all conflicts manually" out
>  '
>
>  test_expect_success 'failed --rebase shows advice' '
> @@ -354,7 +354,7 @@ test_expect_success 'failed --rebase shows advice' '
>         git checkout -f -b fails-to-rebase HEAD^ &&
>         test_commit v2-without-cr file "2" file2-lf &&
>         test_must_fail git pull --rebase . diverging 2>err >out &&
> -       test_i18ngrep "Resolve all conflicts manually" err
> +       test_i18ngrep "Resolve all conflicts manually" out
>  '
>
>  test_expect_success '--rebase fails with multiple branches' '
> @@ -774,8 +774,7 @@ test_expect_success 'git pull --rebase does not reapply old patches' '
>         (
>                 cd dst &&
>                 test_must_fail git pull --rebase &&
> -               cat .git/rebase-merge/done .git/rebase-merge/git-rebase-todo >work &&
> -               grep -v -e \# -e ^$ work >patches &&
> +               find .git/rebase-apply -name "000*" >patches &&
>                 test_line_count = 1 patches &&
>                 rm -f work
>         )
> diff --git a/t/t9106-git-svn-commit-diff-clobber.sh b/t/t9106-git-svn-commit-diff-clobber.sh
> index aec45bca3b..dbe8deac0d 100755
> --- a/t/t9106-git-svn-commit-diff-clobber.sh
> +++ b/t/t9106-git-svn-commit-diff-clobber.sh
> @@ -92,8 +92,7 @@ test_expect_success 'multiple dcommit from git svn will not clobber svn' "
>
>
>  test_expect_success 'check that rebase really failed' '
> -       git status >output &&
> -       grep currently.rebasing output
> +       test -d .git/rebase-apply
>  '
>
>  test_expect_success 'resolve, continue the rebase and dcommit' "

Looks good to me.  I'll look into the regressions.