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author | Junio C Hamano <gitster@pobox.com> | 2021-12-20 22:53:43 (GMT) |
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committer | Junio C Hamano <gitster@pobox.com> | 2021-12-20 22:55:02 (GMT) |
commit | bd2bc94252a47443e19d366f8cc9626d4f92df7a (patch) | |
tree | 692b1b4563512d4bd54faab15649282f1bf2a31d /fmt-merge-msg.c | |
parent | cd3e606211bb1cf8bc57f7d76bab98cc17a150bc (diff) | |
download | git-bd2bc94252a47443e19d366f8cc9626d4f92df7a.zip git-bd2bc94252a47443e19d366f8cc9626d4f92df7a.tar.gz git-bd2bc94252a47443e19d366f8cc9626d4f92df7a.tar.bz2 |
merge: allow to pretend a merge is made into a different branch
When a series of patches for a topic-B depends on having topic-A,
the workflow to prepare the topic-B branch would look like this:
$ git checkout -b topic-B main
$ git merge --no-ff --no-edit topic-A
$ git am <mbox-for-topic-B
When topic-A gets updated, recreating the first merge and rebasing
the rest of the topic-B, all on detached HEAD, is a useful
technique. After updating topic-A with its new round of patches:
$ git checkout topic-B
$ prev=$(git rev-parse 'HEAD^{/^Merge branch .topic-A. into}')
$ git checkout --detach $prev^1
$ git merge --no-ff --no-edit topic-A
$ git rebase --onto HEAD $prev @{-1}^0
$ git checkout -B @{-1}
This will
(0) check out the current topic-B.
(1) find the previous merge of topic-A into topic-B.
(2) detach the HEAD to the parent of the previous merge.
(3) merge the updated topic-A to it.
(4) reapply the patches to rebuild the rest of topic-B.
(5) update topic-B with the result.
without contaminating the reflog of topic-B too much. topic-B@{1}
is the "logically previous" state before topic-A got updated, for
example. At (4), comparison (e.g. range-diff) between HEAD and
@{-1} is a meaningful way to sanity check the result, and the same
can be done at (5) by comparing topic-B and topic-B@{1}.
But there is one glitch. The merge into the detached HEAD done in
the step (3) above gives us "Merge branch 'topic-A' into HEAD", and
does not say "into topic-B".
Teach the "--into-name=<branch>" option to "git merge" and its
underlying "git fmt-merge-message", to pretend as if we were merging
into <branch>, no matter what branch we are actually merging into,
when they prepare the merge message. The pretend name honors the
usual "into <target>" suppression mechanism, which can be seen in
the tests added here.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'fmt-merge-msg.c')
-rw-r--r-- | fmt-merge-msg.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/fmt-merge-msg.c b/fmt-merge-msg.c index 5216191..d255945 100644 --- a/fmt-merge-msg.c +++ b/fmt-merge-msg.c @@ -649,12 +649,15 @@ int fmt_merge_msg(struct strbuf *in, struct strbuf *out, memset(&merge_parents, 0, sizeof(merge_parents)); - /* get current branch */ + /* learn the commit that we merge into and the current branch name */ current_branch = current_branch_to_free = resolve_refdup("HEAD", RESOLVE_REF_READING, &head_oid, NULL); if (!current_branch) die("No current branch"); - if (starts_with(current_branch, "refs/heads/")) + + if (opts->into_name) + current_branch = opts->into_name; + else if (starts_with(current_branch, "refs/heads/")) current_branch += 11; find_merge_parents(&merge_parents, in, &head_oid); |