| Message ID | xmqqh7dbplji.fsf@gitster.g (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] pull: --ff-only should make it a noop when already-up-to-date | expand |
On Wed, Oct 20, 2021 at 12:02:09PM -0700, Junio C Hamano wrote: > Earlier, we made sure that "git pull --ff-only" (and "git -c > pull.ff=only pull") errors out when our current HEAD is not an > ancestor of the tip of the history we are merging, but the condition > to trigger the error was implemented incorrectly. > > Imagine you forked from a remote branch, built your history on top > of it, and then attempted to pull from them again. If they have not > made any update in the meantime, our current HEAD is obviously not > their ancestor, and this new error triggers. > > Without the --ff-only option, we just report that there is no need > to pull; we did the same historically with --ff-only, too. Thanks, this looks good to me overall, and I agree this is a regression we should try to fix promptly (so thank you for jumping on it). > Make sure we do not fail with the recently added check to restore > the historycal behaviour. Not sure if "historycal" is a typo or some clever pun. :) > +/* > + * Is orig_head is a descendant of _all_ merge_heads? s/is a/a/ > +static int already_up_to_date(struct object_id *orig_head, > + struct oid_array *merge_heads) > +{ > + int i; > + struct commit *ours; > + > + ours = lookup_commit_reference(the_repository, orig_head); > + for (i = 0; i < merge_heads->nr; i++) { > + struct commit_list *list = NULL; > + struct commit *theirs; > + int ok; > + > + theirs = lookup_commit_reference(the_repository, &merge_heads->oid[i]); > + commit_list_insert(theirs, &list); > + ok = repo_is_descendant_of(the_repository, ours, list); > + free_commit_list(list); > + if (!ok) > + return 0; > + } > + return 1; > +} You answered all of my "what about..." questions from before elsewhere in the thread, so this looks correct. > +test_expect_success 'already-up-to-date pull succeeds with "only" in pull.ff' ' > + git reset --hard c1 && > + test_config pull.ff only && > + git pull . c0 && > + test "$(git rev-parse HEAD)" = "$(git rev-parse c1)" > +' > + > +test_expect_success 'already-up-to-date pull/rebase succeeds with "only" in pull.ff' ' > + git reset --hard c1 && > + test_config pull.ff only && > + git -c pull.rebase=true pull . c0 && > + test "$(git rev-parse HEAD)" = "$(git rev-parse c1)" > +' And these tests cover the cases I'd expect. The use of "test" with process substitution looks a bit funny to me these days, but it does match the surrounding code (and losing the exit codes isn't a big deal here, as we are not testing rev-parse). The combo of "test_config" and "git -c" is unusual, but I don't see anything wrong with it. -Peff
On Wed, Oct 20, 2021 at 2:45 PM Jeff King <peff@peff.net> wrote: > > On Wed, Oct 20, 2021 at 12:02:09PM -0700, Junio C Hamano wrote: > > > Earlier, we made sure that "git pull --ff-only" (and "git -c > > pull.ff=only pull") errors out when our current HEAD is not an > > ancestor of the tip of the history we are merging, but the condition > > to trigger the error was implemented incorrectly. > > > > Imagine you forked from a remote branch, built your history on top > > of it, and then attempted to pull from them again. If they have not > > made any update in the meantime, our current HEAD is obviously not > > their ancestor, and this new error triggers. > > > > Without the --ff-only option, we just report that there is no need > > to pull; we did the same historically with --ff-only, too. > > Thanks, this looks good to me overall, and I agree this is a regression > we should try to fix promptly (so thank you for jumping on it). It looks like you guys got this under control in no time. Thank you so much! -Alex
diff --git a/builtin/pull.c b/builtin/pull.c index b311ea6b9d..05f1f0e446 100644 --- a/builtin/pull.c +++ b/builtin/pull.c @@ -933,6 +933,33 @@ static int get_can_ff(struct object_id *orig_head, return ret; } +/* + * Is orig_head is a descendant of _all_ merge_heads? + * unfortunately is_descendant_of() cannot be used as it is to + * ask if orig_head is a descendant of at least one of them. + */ +static int already_up_to_date(struct object_id *orig_head, + struct oid_array *merge_heads) +{ + int i; + struct commit *ours; + + ours = lookup_commit_reference(the_repository, orig_head); + for (i = 0; i < merge_heads->nr; i++) { + struct commit_list *list = NULL; + struct commit *theirs; + int ok; + + theirs = lookup_commit_reference(the_repository, &merge_heads->oid[i]); + commit_list_insert(theirs, &list); + ok = repo_is_descendant_of(the_repository, ours, list); + free_commit_list(list); + if (!ok) + return 0; + } + return 1; +} + static void show_advice_pull_non_ff(void) { advise(_("You have divergent branches and need to specify how to reconcile them.\n" @@ -1074,7 +1101,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix) /* ff-only takes precedence over rebase */ if (opt_ff && !strcmp(opt_ff, "--ff-only")) { - if (!can_ff) + if (!can_ff && !already_up_to_date(&orig_head, &merge_heads)) die_ff_impossible(); opt_rebase = REBASE_FALSE; } diff --git a/t/t7601-merge-pull-config.sh b/t/t7601-merge-pull-config.sh index 1f652f433e..6275641b9c 100755 --- a/t/t7601-merge-pull-config.sh +++ b/t/t7601-merge-pull-config.sh @@ -2,7 +2,7 @@ test_description='git merge -Testing pull.* configuration parsing.' +Testing pull.* configuration parsing and other things.' . ./test-lib.sh @@ -387,6 +387,20 @@ test_expect_success 'pull prevents non-fast-forward with "only" in pull.ff' ' test_must_fail git pull . c3 ' +test_expect_success 'already-up-to-date pull succeeds with "only" in pull.ff' ' + git reset --hard c1 && + test_config pull.ff only && + git pull . c0 && + test "$(git rev-parse HEAD)" = "$(git rev-parse c1)" +' + +test_expect_success 'already-up-to-date pull/rebase succeeds with "only" in pull.ff' ' + git reset --hard c1 && + test_config pull.ff only && + git -c pull.rebase=true pull . c0 && + test "$(git rev-parse HEAD)" = "$(git rev-parse c1)" +' + test_expect_success 'merge c1 with c2 (ours in pull.twohead)' ' git reset --hard c1 && git config pull.twohead ours &&
Earlier, we made sure that "git pull --ff-only" (and "git -c pull.ff=only pull") errors out when our current HEAD is not an ancestor of the tip of the history we are merging, but the condition to trigger the error was implemented incorrectly. Imagine you forked from a remote branch, built your history on top of it, and then attempted to pull from them again. If they have not made any update in the meantime, our current HEAD is obviously not their ancestor, and this new error triggers. Without the --ff-only option, we just report that there is no need to pull; we did the same historically with --ff-only, too. Make sure we do not fail with the recently added check to restore the historycal behaviour. Reported-by: Kenneth Arnold <ka37@calvin.edu> Helped-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com> --- * With tests and a proposed log message. builtin/pull.c | 29 ++++++++++++++++++++++++++++- t/t7601-merge-pull-config.sh | 16 +++++++++++++++- 2 files changed, 43 insertions(+), 2 deletions(-)