Junio C HamanoWhen 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-BWhen 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 "--detached-head-name=<branch>" option to "git merge" and its underlying "git fmt-merge-message", to pretend as if we were merging into <branch> (instead of HEAD) 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> --- Documentation/git-fmt-merge-msg.txt | 6 ++++- Documentation/git-merge.txt | 7 +++++- builtin/fmt-merge-msg.c | 4 ++++ builtin/merge.c | 4 ++++ fmt-merge-msg.c | 2 ++ fmt-merge-msg.h | 1 + t/t6200-fmt-merge-msg.sh | 35 ++++++++++++++++++++++++++++- 7 files changed, 56 insertions(+), 3 deletions(-)
Show changes to 7 files +56 −3
Documentation/git-fmt-merge-msg.txt, Documentation/git-merge.txt, builtin/fmt-merge-msg.c, builtin/merge.c, fmt-merge-msg.c, fmt-merge-msg.h, t/t6200-fmt-merge-msg.sh
diff --git a/Documentation/git-fmt-merge-msg.txt b/Documentation/git-fmt-merge-msg.txt index 6793d8fc05..235276752f 100644 --- a/Documentation/git-fmt-merge-msg.txt +++ b/Documentation/git-fmt-merge-msg.txt @@ -9,7 +9,7 @@ git-fmt-merge-msg - Produce a merge commit message SYNOPSIS -------- [verse] -'git fmt-merge-msg' [-m <message>] [--log[=<n>] | --no-log] +'git fmt-merge-msg' [-m <message>] [--detached-head-name <branch>] [--log[=<n>] | --no-log] 'git fmt-merge-msg' [-m <message>] [--log[=<n>] | --no-log] -F <file> DESCRIPTION @@ -44,6 +44,10 @@ OPTIONS Use <message> instead of the branch names for the first line of the log message. For use with `--log`. +--detached-head-name <branch>:: + When merging into a detached HEAD, prepare the merge + message as if merging to the branch `<branch>` instead. + -F <file>:: --file <file>:: Take the list of merged objects from <file> instead of diff --git a/Documentation/git-merge.txt b/Documentation/git-merge.txt index e8cecf5a51..c369c1776a 100644 --- a/Documentation/git-merge.txt +++ b/Documentation/git-merge.txt @@ -12,7 +12,8 @@ SYNOPSIS 'git merge' [-n] [--stat] [--no-commit] [--squash] [--[no-]edit] [--no-verify] [-s <strategy>] [-X <strategy-option>] [-S[<keyid>]] [--[no-]allow-unrelated-histories] - [--[no-]rerere-autoupdate] [-m <msg>] [-F <file>] [<commit>...] + [--[no-]rerere-autoupdate] [-m <msg>] [-F <file>] + [--detached-head-name <branch>] [<commit>...] 'git merge' (--continue | --abort | --quit) DESCRIPTION @@ -76,6 +77,10 @@ The 'git fmt-merge-msg' command can be used to give a good default for automated 'git merge' invocations. The automated message can include the branch description. +--detached-head-name <branch>:: + When merging into a detached HEAD, prepare the default merge + message as if merging to the branch `<branch>` instead. + -F <file>:: --file=<file>:: Read the commit message to be used for the merge commit (in diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c index 48a8699de7..255c45b17a 100644 --- a/builtin/fmt-merge-msg.c +++ b/builtin/fmt-merge-msg.c @@ -12,6 +12,7 @@ int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix) { const char *inpath = NULL; const char *message = NULL; + char *detached_head_name = NULL; int shortlog_len = -1; struct option options[] = { { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"), @@ -23,6 +24,8 @@ int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix) DEFAULT_MERGE_LOG_LEN }, OPT_STRING('m', "message", &message, N_("text"), N_("use <text> as start of message")), + OPT_STRING(0, "detached", &detached_head_name, N_("name"), + N_("use <name> instead of detached HEAD")), OPT_FILENAME('F', "file", &inpath, N_("file to read from")), OPT_END() }; @@ -56,6 +59,7 @@ int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix) opts.add_title = !message; opts.credit_people = 1; opts.shortlog_len = shortlog_len; + opts.detached_head_name = detached_head_name; ret = fmt_merge_msg(&input, &output, &opts); if (ret) diff --git a/builtin/merge.c b/builtin/merge.c index 5f0476b0b7..d0b624bd65 100644 --- a/builtin/merge.c +++ b/builtin/merge.c @@ -87,6 +87,7 @@ static int signoff; static const char *sign_commit; static int autostash; static int no_verify; +static char *detached_head_name; static struct strategy all_strategy[] = { { "recursive", NO_TRIVIAL }, @@ -286,6 +287,8 @@ static struct option builtin_merge_options[] = { { OPTION_LOWLEVEL_CALLBACK, 'F', "file", &merge_msg, N_("path"), N_("read message from file"), PARSE_OPT_NONEG, NULL, 0, option_read_message }, + OPT_STRING(0, "detached", &detached_head_name, N_("name"), + N_("use <name> instead of detached HEAD")), OPT__VERBOSITY(&verbosity), OPT_BOOL(0, "abort", &abort_current_merge, N_("abort the current in-progress merge")), @@ -1121,6 +1124,7 @@ static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *mer opts.add_title = !have_message; opts.shortlog_len = shortlog_len; opts.credit_people = (0 < option_edit); + opts.detached_head_name = detached_head_name; fmt_merge_msg(merge_names, merge_msg, &opts); if (merge_msg->len) diff --git a/fmt-merge-msg.c b/fmt-merge-msg.c index 5216191488..72b96d45e6 100644 --- a/fmt-merge-msg.c +++ b/fmt-merge-msg.c @@ -656,6 +656,8 @@ int fmt_merge_msg(struct strbuf *in, struct strbuf *out, die("No current branch"); if (starts_with(current_branch, "refs/heads/")) current_branch += 11; + else if (!strcmp(current_branch, "HEAD") && opts->detached_head_name) + current_branch = opts->detached_head_name; find_merge_parents(&merge_parents, in, &head_oid); diff --git a/fmt-merge-msg.h b/fmt-merge-msg.h index f2ab0e0085..b5f3a5ec54 100644 --- a/fmt-merge-msg.h +++ b/fmt-merge-msg.h @@ -9,6 +9,7 @@ struct fmt_merge_msg_opts { unsigned add_title:1, credit_people:1; int shortlog_len; + const char *detached_head_name; }; extern int merge_log_config; diff --git a/t/t6200-fmt-merge-msg.sh b/t/t6200-fmt-merge-msg.sh index 06c5fb5615..b6fa76189e 100755 --- a/t/t6200-fmt-merge-msg.sh +++ b/t/t6200-fmt-merge-msg.sh @@ -573,7 +573,28 @@ test_expect_success 'merge-msg with "merging" an annotated tag' ' test_cmp expected .git/MERGE_MSG ' +test_expect_success 'merge --detached=<name>' ' + test_when_finished "git checkout main" && + git checkout -B side main && + git commit --allow-empty -m "One step ahead" && + + git checkout --detach main && + git merge --no-ff side && + git show -s --format="%s" >full.0 && + head -n1 full.0 >actual && + # expect that HEAD is shown as-is + grep -e "Merge branch .side. into HEAD$" actual && + + git reset --hard main && + git merge --no-ff --detached=main side && + git show -s --format="%s" >full.1 && + head -n1 full.1 >actual && + # expect that we pretend to be merging to main, that is suppressed + grep -e "Merge branch .side.$" actual +' + test_expect_success 'merge.suppressDest configuration' ' + test_when_finished "git checkout main" && git checkout -B side main && git commit --allow-empty -m "One step ahead" && git checkout main && @@ -590,7 +611,19 @@ test_expect_success 'merge.suppressDest configuration' ' git -c merge.suppressDest="ma?*[rn]" fmt-merge-msg <.git/FETCH_HEAD >full.3 && head -n1 full.3 >actual && grep -e "Merge branch .side." actual && - ! grep -e " into main$" actual + ! grep -e " into main$" actual && + + git checkout --detach HEAD && + git -c merge.suppressDest="main" fmt-merge-msg <.git/FETCH_HEAD >full.4 && + head -n1 full.4 >actual && + grep -e "Merge branch .side. into HEAD$" actual && + + git -c merge.suppressDest="main" fmt-merge-msg \ + --detached=main <.git/FETCH_HEAD >full.5 && + head -n1 full.5 >actual && + grep -e "Merge branch .side." actual && + ! grep -e " into main$" actual && + ! grep -e " into HEAD$" actual ' test_done
-- 2.34.1-472-g213ab46be7
