From: Denton Liu <liu.denton@gmail.com>
To: phillip.wood@dunelm.org.uk
Cc: "Git Mailing List" <git@vger.kernel.org>,
"Eric Sunshine" <sunshine@sunshineco.com>,
"Junio C Hamano" <gitster@pobox.com>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
"Johannes Sixt" <j6t@kdbg.org>,
"SZEDER Gábor" <szeder.dev@gmail.com>
Subject: Re: [PATCH v5 3/5] rebase: fast-forward --onto in more cases
Date: Tue, 16 Apr 2019 23:44:20 -0700 [thread overview]
Message-ID: <20190417064420.GA12818@archbookpro.localdomain> (raw)
In-Reply-To: <216aa032-d28e-79ba-6bc7-c4bd3de4321d@gmail.com>
On Tue, Apr 16, 2019 at 02:59:12PM +0100, Phillip Wood wrote:
> Hi Denton
>
> It's good to see rebase fast-forwarding properly when it should
>
> On 15/04/2019 23:29, Denton Liu wrote:
> > Before, when we had the following graph,
> >
> > A---B---C (master)
> > \
> > D (side)
> >
> > running 'git rebase --onto master... master side' would result in D
> > being always rebased, no matter what. However, the desired behavior is
> > that rebase should notice that this is fast-forwardable and do that
> > instead.
> >
> > Add detection to `can_fast_forward` so that this case can be detected
> > and a fast-forward will be performed. First of all, rewrite the function
> > to use gotos which simplifies the logic. Next, since the
> >
> > options.upstream &&
> > !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)
> >
> > conditions were removed in `cmd_rebase`, we reintroduce a substitute in
> > `can_fast_forward`. In particular, checking the merge bases of
> > `upstream` and `head` fixes a failing case in t3416.
> >
> > The abbreviated graph for t3416 is as follows:
> >
> > F---G topic
> > /
> > A---B---C---D---E master
> >
> > and the failing command was
> >
> > git rebase --onto master...topic F topic
> >
> > Before, Git would see that there was one merge base (C), and the merge
> > and onto were the same so it would incorrectly return 1, indicating that
> > we could fast-forward. This would cause the rebased graph to be 'ABCFG'
> > when we were expecting 'ABCG'.
> >
> > With the additional logic, we detect that upstream and head's merge base
> > is F. Since onto isn't F, it means we're not rebasing the full set of
> > commits from master..topic. Since we're excluding some commits, a
> > fast-forward cannot be performed and so we correctly return 0.
> >
> > Add '-f' to test cases that failed as a result of this change because
> > they were not expecting a fast-forward so that a rebase is forced.
> >
> > While we're at it, remove a trailing whitespace from rebase.c.
> >
> > Signed-off-by: Denton Liu <liu.denton@gmail.com>
> > ---
> > builtin/rebase.c | 40 +++++++++++++++++++++++-----------
> > t/t3400-rebase.sh | 2 +-
> > t/t3404-rebase-interactive.sh | 2 +-
> > t/t3432-rebase-fast-forward.sh | 4 ++--
> > 4 files changed, 31 insertions(+), 17 deletions(-)
> >
> > diff --git a/builtin/rebase.c b/builtin/rebase.c
> > index 77deebc65c..7aa6a090d4 100644
> > --- a/builtin/rebase.c
> > +++ b/builtin/rebase.c
> > @@ -895,12 +895,12 @@ static int is_linear_history(struct commit *from, struct commit *to)
> > return 1;
> > }
> > -static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
> > - struct object_id *merge_base)
> > +static int can_fast_forward(struct commit *onto, struct commit *upstream,
> > + struct object_id *head_oid, struct object_id *merge_base)
> > {
> > struct commit *head = lookup_commit(the_repository, head_oid);
> > - struct commit_list *merge_bases;
> > - int res;
> > + struct commit_list *merge_bases = NULL;
> > + int res = 0;
> > if (!head)
> > return 0;
> > @@ -908,12 +908,29 @@ static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
> > merge_bases = get_merge_bases(onto, head);
> > if (merge_bases && !merge_bases->next) {
> > oidcpy(merge_base, &merge_bases->item->object.oid);
> > - res = oideq(merge_base, &onto->object.oid);
> > + if (!oideq(merge_base, &onto->object.oid))
> > + goto done;
> > } else {
> > oidcpy(merge_base, &null_oid);
> > - res = 0;
> > + goto done;
> > }
> > +
> > + if (!upstream)
> > + goto done;
> > +
> > free_commit_list(merge_bases);
> > + merge_bases = get_merge_bases(upstream, head);
> > + if (merge_bases && !merge_bases->next) {
> > + if (!oideq(&onto->object.oid, &merge_bases->item->object.oid))
> > + goto done;
> > + } else
> > + goto done;
> > +
> > + res = 1;
> > +
> > +done:
> > + if (merge_bases)
> > + free_commit_list(merge_bases);
> > return res && is_linear_history(onto, head);
> > }
>
> I had a hard time following all those gotos. When you 'goto done' in both
> branches of an if statement it is hard to work out which cases fall through
> to the rest of the code. If I've understood it correctly I think it is
> clearer as
>
> merge_bases = get_merge_bases(onto, head);
> if (merge_bases && !merge_bases->next) {
> oidcpy(merge_base, &merge_bases->item->object.oid);
> if (oideq(merge_base, &onto->object.oid) && upstream) {
> free_commit_list(merge_bases);
> merge_bases = get_merge_bases(upstream, head);
> if (merge_bases && !merge_bases->next)
> if (oideq(&onto->object.oid,
> &merge_bases->item->object.oid))
> res = 1;
> }
> } else {
> oidcpy(merge_base, &null_oid);
> }
>
> if (merge_bases)
> free_commit_list(merge_bases);
> return res && is_linear_history(onto, head);
> }
>
> The nested if's aren't great but I think it is easier to follow
I am pretty impartial between gotos and ifs. If no one else has any
strong opinions between the two, I'll reroll with ifs.
>
> > @@ -1682,13 +1699,10 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
> > /*
> > * Check if we are already based on onto with linear history,
> > - * but this should be done only when upstream and onto are the same
> > - * and if this is not an interactive rebase.
> > + * but this should be done if this is not an interactive rebase.
> > */
> > - if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
> > - !is_interactive(&options) && !options.restrict_revision &&
> > - options.upstream &&
> > - !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
> > + if (can_fast_forward(options.onto, options.upstream, &options.orig_head, &merge_base) &&
>
> This is rather long, perhaps break the argument list
Thanks, will do.
>
> Best Wishes
>
> Phillip
> > + !is_interactive(&options) && !options.restrict_revision) {
> > int flag;
> > if (!(options.flags & REBASE_FORCE)) {
> > @@ -1782,7 +1796,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
> > strbuf_addf(&msg, "%s: checkout %s",
> > getenv(GIT_REFLOG_ACTION_ENVIRONMENT), options.onto_name);
> > if (reset_head(&options.onto->object.oid, "checkout", NULL,
> > - RESET_HEAD_DETACH | RESET_ORIG_HEAD |
> > + RESET_HEAD_DETACH | RESET_ORIG_HEAD |
> > RESET_HEAD_RUN_POST_CHECKOUT_HOOK,
> > NULL, msg.buf))
> > die(_("Could not detach HEAD"));
> > diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
> > index 460d0523be..604d624ff8 100755
> > --- a/t/t3400-rebase.sh
> > +++ b/t/t3400-rebase.sh
> > @@ -295,7 +295,7 @@ test_expect_success 'rebase--am.sh and --show-current-patch' '
> > echo two >>init.t &&
> > git commit -a -m two &&
> > git tag two &&
> > - test_must_fail git rebase --onto init HEAD^ &&
> > + test_must_fail git rebase -f --onto init HEAD^ &&
> > GIT_TRACE=1 git rebase --show-current-patch >/dev/null 2>stderr &&
> > grep "show.*$(git rev-parse two)" stderr
> > )
> > diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
> > index b60b11f9f2..f054186cc7 100755
> > --- a/t/t3404-rebase-interactive.sh
> > +++ b/t/t3404-rebase-interactive.sh
> > @@ -1066,7 +1066,7 @@ test_expect_success C_LOCALE_OUTPUT 'rebase --edit-todo does not work on non-int
> > git reset --hard &&
> > git checkout conflict-branch &&
> > set_fake_editor &&
> > - test_must_fail git rebase --onto HEAD~2 HEAD~ &&
> > + test_must_fail git rebase -f --onto HEAD~2 HEAD~ &&
> > test_must_fail git rebase --edit-todo &&
> > git rebase --abort
> > '
> > diff --git a/t/t3432-rebase-fast-forward.sh b/t/t3432-rebase-fast-forward.sh
> > index 4f04d67fd7..d0e5b1f3e6 100755
> > --- a/t/t3432-rebase-fast-forward.sh
> > +++ b/t/t3432-rebase-fast-forward.sh
> > @@ -64,9 +64,9 @@ test_expect_success 'add work to upstream' '
> > changes='our and their changes'
> > test_rebase_same_head success --onto B B
> > test_rebase_same_head success --onto B... B
> > -test_rebase_same_head failure --onto master... master
> > +test_rebase_same_head success --onto master... master
> > test_rebase_same_head failure --fork-point --onto B B
> > test_rebase_same_head failure --fork-point --onto B... B
> > -test_rebase_same_head failure --fork-point --onto master... master
> > +test_rebase_same_head success --fork-point --onto master... master
> > test_done
> >
next prev parent reply other threads:[~2019-04-17 6:44 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-23 15:25 [PATCH 0/3] rebase: learn --keep-base Denton Liu
2019-03-23 15:25 ` [PATCH 1/3] rebase: teach rebase --keep-base Denton Liu
2019-03-24 3:46 ` Eric Sunshine
2019-03-24 13:20 ` Junio C Hamano
2019-03-25 0:06 ` Denton Liu
2019-03-25 5:41 ` Denton Liu
2019-04-01 10:45 ` Junio C Hamano
2019-03-24 13:37 ` Junio C Hamano
2019-03-25 5:47 ` Denton Liu
2019-03-25 18:50 ` Johannes Schindelin
2019-03-25 19:29 ` Denton Liu
2019-03-26 13:27 ` Johannes Schindelin
2019-03-23 15:25 ` [PATCH 2/3] t3416: test " Denton Liu
2019-03-23 15:25 ` [PATCH 3/3] git-rebase.txt: document --keep-base option Denton Liu
2019-03-24 13:15 ` [PATCH 0/3] rebase: learn --keep-base Junio C Hamano
2019-03-25 0:04 ` Denton Liu
2019-04-01 10:45 ` Junio C Hamano
2019-03-26 14:35 ` Ævar Arnfjörð Bjarmason
2019-03-26 17:50 ` Denton Liu
2019-03-26 20:35 ` Ævar Arnfjörð Bjarmason
2019-03-26 21:30 ` Denton Liu
2019-03-27 15:39 ` Ævar Arnfjörð Bjarmason
2019-03-28 22:17 ` [PATCH v2] rebase: teach rebase --keep-base Denton Liu
2019-03-28 23:13 ` Ævar Arnfjörð Bjarmason
2019-03-29 15:47 ` Johannes Schindelin
2019-03-29 17:52 ` Denton Liu
2019-04-01 10:46 ` Junio C Hamano
2019-04-01 20:51 ` [PATCH v3 0/4] " Denton Liu
2019-04-01 20:51 ` [PATCH v3 1/4] t3431: add rebase --fork-point tests Denton Liu
2019-04-04 20:28 ` Denton Liu
2019-04-05 11:15 ` SZEDER Gábor
2019-04-08 4:38 ` Junio C Hamano
2019-04-05 14:55 ` Johannes Schindelin
2019-04-05 17:25 ` Denton Liu
2019-04-05 17:51 ` Johannes Sixt
2019-04-05 18:51 ` Johannes Schindelin
2019-04-05 20:19 ` Johannes Schindelin
2019-04-05 21:10 ` SZEDER Gábor
2019-04-01 20:51 ` [PATCH v3 2/4] t3432: test rebase fast-forward behavior Denton Liu
2019-04-01 20:52 ` [PATCH v3 3/4] rebase: fast-forward --onto in more cases Denton Liu
2019-04-02 1:25 ` Junio C Hamano
2019-04-02 1:48 ` Junio C Hamano
2019-04-02 4:44 ` Denton Liu
2019-04-01 20:52 ` [PATCH v3 4/4] rebase: teach rebase --keep-base Denton Liu
2019-04-05 21:39 ` [PATCH v4 0/4] " Denton Liu
2019-04-05 21:40 ` [PATCH v4 1/4] t3431: add rebase --fork-point tests Denton Liu
2019-04-05 21:40 ` [PATCH v4 2/4] t3432: test rebase fast-forward behavior Denton Liu
2019-04-05 21:40 ` [PATCH v4 3/4] rebase: fast-forward --onto in more cases Denton Liu
2019-04-05 21:40 ` [PATCH v4 4/4] rebase: teach rebase --keep-base Denton Liu
2019-04-15 22:29 ` [PATCH v5 0/5] " Denton Liu
2019-04-15 22:29 ` [PATCH v5 1/5] t3431: add rebase --fork-point tests Denton Liu
2019-04-15 22:29 ` [PATCH v5 2/5] t3432: test rebase fast-forward behavior Denton Liu
2019-04-15 22:29 ` [PATCH v5 3/5] rebase: fast-forward --onto in more cases Denton Liu
2019-04-16 6:26 ` Junio C Hamano
2019-04-16 13:59 ` Phillip Wood
2019-04-17 6:44 ` Denton Liu [this message]
2019-04-17 14:14 ` Phillip Wood
2019-04-19 17:08 ` Denton Liu
2019-04-15 22:29 ` [PATCH v5 4/5] rebase: fast-forward --fork-point " Denton Liu
2019-04-15 22:29 ` [PATCH v5 5/5] rebase: teach rebase --keep-base Denton Liu
2019-04-17 18:01 ` [PATCH v6 0/5] " Denton Liu
2019-04-17 18:01 ` [PATCH v6 1/6] t3431: add rebase --fork-point tests Denton Liu
2019-04-17 18:01 ` [PATCH v6 2/6] t3432: test rebase fast-forward behavior Denton Liu
2019-04-17 18:01 ` [PATCH v6 3/6] rebase: refactor can_fast_forward into goto tower Denton Liu
2019-04-17 18:01 ` [PATCH v6 4/6] rebase: fast-forward --onto in more cases Denton Liu
2019-04-17 19:59 ` Phillip Wood
2019-04-17 18:01 ` [PATCH v6 5/6] rebase: fast-forward --fork-point " Denton Liu
2019-04-17 18:01 ` [PATCH v6 6/6] rebase: teach rebase --keep-base Denton Liu
2019-04-21 8:11 ` [PATCH v7 0/6] rebase: learn --keep-base Denton Liu
2019-04-21 8:11 ` [PATCH v7 1/6] t3431: add rebase --fork-point tests Denton Liu
2019-04-23 23:12 ` Denton Liu
2019-04-21 8:11 ` [PATCH v7 2/6] t3432: test rebase fast-forward behavior Denton Liu
2019-04-21 8:11 ` [PATCH v7 3/6] rebase: refactor can_fast_forward into goto tower Denton Liu
2019-04-21 8:11 ` [PATCH v7 4/6] rebase: fast-forward --onto in more cases Denton Liu
2019-04-21 8:11 ` [PATCH v7 5/6] rebase: fast-forward --fork-point " Denton Liu
2019-04-21 8:11 ` [PATCH v7 6/6] rebase: teach rebase --keep-base Denton Liu
2019-05-08 0:12 ` [RFC WIP PATCH v8 00/13] learn --keep-base & more Ævar Arnfjörð Bjarmason
2019-05-08 3:57 ` Junio C Hamano
2019-07-19 19:14 ` Junio C Hamano
2019-07-19 21:01 ` Denton Liu
2019-08-25 9:11 ` [PATCH v9 0/9] rebase: learn --keep-base and improvements on fast-forward behaviour Denton Liu
2019-08-25 9:11 ` [PATCH v9 1/9] t3431: add rebase --fork-point tests Denton Liu
2019-08-25 9:12 ` [PATCH v9 2/9] t3432: test rebase fast-forward behavior Denton Liu
2019-08-25 9:12 ` [PATCH v9 3/9] t3432: distinguish "noop-same" v.s. "work-same" in "same head" tests Denton Liu
2019-08-25 9:12 ` [PATCH v9 4/9] t3432: test for --no-ff's interaction with fast-forward Denton Liu
2019-08-25 9:12 ` [PATCH v9 5/9] rebase: refactor can_fast_forward into goto tower Denton Liu
2019-08-25 13:17 ` Pratyush Yadav
2019-08-26 23:17 ` Denton Liu
2019-08-25 9:12 ` [PATCH v9 6/9] rebase: fast-forward --onto in more cases Denton Liu
2019-08-25 9:12 ` [PATCH v9 7/9] rebase: fast-forward --fork-point " Denton Liu
2019-08-25 9:12 ` [PATCH v9 8/9] rebase tests: test linear branch topology Denton Liu
2019-08-25 9:12 ` [PATCH v9 9/9] rebase: teach rebase --keep-base Denton Liu
2019-08-25 22:59 ` Philip Oakley
2019-08-26 19:37 ` [PATCH v9 0/9] rebase: learn --keep-base and improvements on fast-forward behaviour Junio C Hamano
2019-08-27 5:37 ` [PATCH v10 " Denton Liu
2019-08-27 5:37 ` [PATCH v10 1/9] t3431: add rebase --fork-point tests Denton Liu
2019-08-27 5:37 ` [PATCH v10 2/9] t3432: test rebase fast-forward behavior Denton Liu
2019-08-27 5:37 ` [PATCH v10 3/9] t3432: distinguish "noop-same" v.s. "work-same" in "same head" tests Denton Liu
2019-08-27 5:37 ` [PATCH v10 4/9] t3432: test for --no-ff's interaction with fast-forward Denton Liu
2019-08-27 8:11 ` SZEDER Gábor
2019-08-27 5:37 ` [PATCH v10 5/9] rebase: refactor can_fast_forward into goto tower Denton Liu
2019-08-27 5:37 ` [PATCH v10 6/9] rebase: fast-forward --onto in more cases Denton Liu
2019-08-27 5:38 ` [PATCH v10 7/9] rebase: fast-forward --fork-point " Denton Liu
2019-08-27 5:38 ` [PATCH v10 8/9] rebase tests: test linear branch topology Denton Liu
2019-08-27 5:38 ` [PATCH v10 9/9] rebase: teach rebase --keep-base Denton Liu
2019-05-08 0:12 ` [RFC WIP PATCH v8 01/13] t3431: add rebase --fork-point tests Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 02/13] t3432: test rebase fast-forward behavior Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 03/13] t3432: distinguish "noop-same" v.s. "work-same" in "same head" tests Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 04/13] t3432: test for --no-ff's interaction with fast-forward Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 05/13] rebase: refactor can_fast_forward into goto tower Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 06/13] rebase: fast-forward --onto in more cases Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 07/13] rebase: fast-forward --fork-point " Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 08/13] rebase: teach rebase --keep-base Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 09/13] rebase tests: test linear branch topology Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 10/13] rebase: don't rebase linear topology with --fork-point Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 11/13] rebase: eliminate side-effects from can_fast_forward() Ævar Arnfjörð Bjarmason
2019-05-17 21:16 ` Johannes Schindelin
2019-05-08 0:12 ` [RFC WIP PATCH v8 12/13] rebase: add a should_fast_forward() utility function Ævar Arnfjörð Bjarmason
2019-05-08 0:12 ` [RFC WIP PATCH v8 13/13] WIP: can_fast_forward() support for --preserve-merges and --rebase-merges Ævar Arnfjörð Bjarmason
2019-05-17 22:02 ` Johannes Schindelin
2019-04-06 19:44 ` [PATCH v3 0/4] rebase: teach rebase --keep-base Ævar Arnfjörð Bjarmason
2019-04-06 20:38 ` Denton Liu
2019-04-13 21:10 ` Ævar Arnfjörð Bjarmason
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190417064420.GA12818@archbookpro.localdomain \
--to=liu.denton@gmail.com \
--cc=Johannes.Schindelin@gmx.de \
--cc=avarab@gmail.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=j6t@kdbg.org \
--cc=phillip.wood@dunelm.org.uk \
--cc=sunshine@sunshineco.com \
--cc=szeder.dev@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).