From: Li Chen <chenl311@xxxxxxxxxxxxxxx>
Implement a new `--trailer <text>` option for `git rebase`
(support merge backend only now), which appends arbitrary
trailer lines to each rebased commit message. Reject early
if used with the apply backend (git am) since it lacks
message‑filter/trailer hook. Automatically set REBASE_FORCE when
any trailer is supplied.
Reviewed-by: Li Chen <chenl311@xxxxxxxxxxxxxxx>
---
Documentation/git-rebase.adoc | 8 +++
builtin/rebase.c | 70 ++++++++++++++++++++++
sequencer.c | 13 ++++
sequencer.h | 2 +
t/meson.build | 1 +
t/t3440-rebase-trailer.sh | 108 ++++++++++++++++++++++++++++++++++
6 files changed, 202 insertions(+)
create mode 100755 t/t3440-rebase-trailer.sh
diff --git a/Documentation/git-rebase.adoc b/Documentation/git-rebase.adoc
index 1f3d152035..757016e529 100644
--- a/Documentation/git-rebase.adoc
+++ b/Documentation/git-rebase.adoc
@@ -525,6 +525,14 @@ See also INCOMPATIBLE OPTIONS below.
Append a `Reviewed-by:` trailer whose value is taken from the
current committer identity, exactly like `--signoff` appends a
Signed-off-by:` trailer.
+
+--trailer <trailer>::
+ Append the given trailer line(s) to every rebased commit
+ message, processed via linkgit:git-interpret-trailers[1].
+ When this option is present *rebase automatically enables*
+ `--force-rebase` so that fast‑forwarded commits are also
+ rewritten.
+
See also INCOMPATIBLE OPTIONS below.
-i::
diff --git a/builtin/rebase.c b/builtin/rebase.c
index b288aedfb1..df65a1e040 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -36,6 +36,9 @@
#include "reset.h"
#include "trace2.h"
#include "hook.h"
+#include "trailer.h"
+
+static const char trailer_state_name[] = "trailer";
static char const * const builtin_rebase_usage[] = {
N_("git rebase [-i] [options] [--exec <cmd>] "
@@ -46,6 +49,8 @@ static char const * const builtin_rebase_usage[] = {
NULL
};
+static struct strvec trailer_args = STRVEC_INIT;
+
static GIT_PATH_FUNC(path_squash_onto, "rebase-merge/squash-onto")
static GIT_PATH_FUNC(path_interactive, "rebase-merge/interactive")
static GIT_PATH_FUNC(apply_dir, "rebase-apply")
@@ -114,6 +119,7 @@ struct rebase_options {
char *reflog_action;
int signoff;
int reviewby;
+ struct strvec trailer_args;
int allow_rerere_autoupdate;
int keep_empty;
int autosquash;
@@ -144,6 +150,7 @@ struct rebase_options {
.flags = REBASE_NO_QUIET, \
.git_am_opts = STRVEC_INIT, \
.exec = STRING_LIST_INIT_NODUP, \
+ .trailer_args = STRVEC_INIT, \
.git_format_patch_opt = STRBUF_INIT, \
.fork_point = -1, \
.reapply_cherry_picks = -1, \
@@ -167,6 +174,7 @@ static void rebase_options_release(struct rebase_options *opts)
free(opts->strategy);
string_list_clear(&opts->strategy_opts, 0);
strbuf_release(&opts->git_format_patch_opt);
+ strvec_clear(&opts->trailer_args);
}
static struct replay_opts get_replay_opts(const struct rebase_options *opts)
@@ -179,6 +187,10 @@ static struct replay_opts get_replay_opts(const struct rebase_options *opts)
replay.signoff = opts->signoff;
replay.reviewby = opts->reviewby;
+
+ for (size_t i = 0; i < opts->trailer_args.nr; i++)
+ strvec_push(&replay.trailer_args, opts->trailer_args.v[i]);
+
replay.allow_ff = !(opts->flags & REBASE_FORCE);
if (opts->allow_rerere_autoupdate)
replay.allow_rerere_auto = opts->allow_rerere_autoupdate;
@@ -437,6 +449,8 @@ static int read_basic_state(struct rebase_options *opts)
struct strbuf head_name = STRBUF_INIT;
struct strbuf buf = STRBUF_INIT;
struct object_id oid;
+ struct strbuf t = STRBUF_INIT, one = STRBUF_INIT;
+ const char *path = state_dir_path(trailer_state_name, opts);
if (!read_oneliner(&head_name, state_dir_path("head-name", opts),
READ_ONELINER_WARN_MISSING) ||
@@ -509,6 +523,22 @@ static int read_basic_state(struct rebase_options *opts)
strbuf_release(&buf);
+ if (strbuf_read_file(&t, path, 0) >= 0) {
+ const char *p = t.buf, *end = t.buf + t.len;
+
+ while (p < end) {
+ const char *nl = memchr(p, '\n', end - p);
+ strbuf_reset(&one);
+ strbuf_add(&one, p, nl ? nl - p : end - p);
+ if (one.len) /* skip empty line */
+ strvec_push(&opts->trailer_args,
+ strbuf_detach(&one, NULL));
+ p = nl ? nl + 1 : end;
+ }
+ strbuf_release(&one);
+ }
+ strbuf_release(&t);
+
return 0;
}
@@ -537,6 +567,28 @@ static int rebase_write_basic_state(struct rebase_options *opts)
if (opts->reviewby)
write_file(state_dir_path("reviewby", opts), "--reviewby");
+ /*
+ * save opts->trailer_args into state_dir/trailer
+ */
+ if (opts->trailer_args.nr) {
+ struct strbuf buf = STRBUF_INIT;
+ size_t i;
+
+ for (i = 0; i < opts->trailer_args.nr; i++) {
+ strbuf_addstr(&buf, opts->trailer_args.v[i]);
+ strbuf_addch(&buf, '\n');
+ }
+ write_file(state_dir_path(trailer_state_name, opts),
+ "%s", buf.buf);
+ strbuf_release(&buf);
+ } else {
+ /*
+ * but if rebase doesn't pass any --trailer，
+ * and state dir still have residual files，let's delete it。
+ */
+ unlink_or_warn(state_dir_path(trailer_state_name, opts));
+ }
+
return 0;
}
@@ -1140,6 +1192,7 @@ int cmd_rebase(int argc,
.flags = PARSE_OPT_NOARG,
.defval = REBASE_DIFFSTAT,
},
+ OPT_PASSTHRU_ARGV(0, "trailer", &trailer_args, N_("trailer"), N_("add custom trailer(s)"), PARSE_OPT_NONEG),
OPT_BOOL(0, "signoff", &options.signoff,
N_("add a Signed-off-by trailer to each commit")),
OPT_BOOL(0, "reviewby", &options.reviewby,
@@ -1292,6 +1345,13 @@ int cmd_rebase(int argc,
builtin_rebase_options,
builtin_rebase_usage, 0);
+ for (i = 0; i < trailer_args.nr; i++)
+ strvec_push(&options.trailer_args, trailer_args.v[i]);
+
+ /* if add --trailer，force rebase */
+ if (options.trailer_args.nr)
+ options.flags |= REBASE_FORCE;
+
if (preserve_merges_selected)
die(_("--preserve-merges was replaced by --rebase-merges\n"
"Note: Your `pull.rebase` configuration may also be set to 'preserve',\n"
@@ -1549,6 +1609,16 @@ int cmd_rebase(int argc,
if (options.root && !options.onto_name)
imply_merge(&options, "--root without --onto");
+ /*
+ * The apply‑based backend (git am) cannot append trailers because
+ * it lacks a message‑filter facility. Reject early, before any
+ * state (index, HEAD, etc.) is modified.
+ */
+ if (options.type == REBASE_APPLY && options.trailer_args.nr)
+ die(_("the --apply backend (git am) cannot currently handle "
+ "--trailer; please omit --apply or use "
+ "the merge/interactive backend"));
+
if (isatty(2) && options.flags & REBASE_NO_QUIET)
strbuf_addstr(&options.git_format_patch_opt, " --progress");
diff --git a/sequencer.c b/sequencer.c
index 01933882ed..b61c668c39 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -429,6 +429,7 @@ void replay_opts_release(struct replay_opts *opts)
free(opts->revs);
replay_ctx_release(ctx);
free(opts->ctx);
+ strvec_clear(&opts->trailer_args);
}
int sequencer_remove_state(struct replay_opts *opts)
@@ -2506,6 +2507,18 @@ static int do_pick_commit(struct repository *r,
_("dropping %s %s -- patch contents already upstream\n"),
oid_to_hex(&commit->object.oid), msg.subject);
} /* else allow == 0 and there's nothing special to do */
+
+ if (!res && opts->trailer_args.nr && !drop_commit) {
+ const char *trailer_file =
+ msg_file ? msg_file : git_path_merge_msg(r);
+
+ if (amend_file_with_trailers(trailer_file,
+ &opts->trailer_args)) {
+ res = error(_("unable to add trailers to commit message"));
+ goto leave;
+ }
+ }
+
if (!opts->no_commit && !drop_commit) {
if (author || command == TODO_REVERT || (flags & AMEND_MSG))
res = do_commit(r, msg_file, author, opts, flags,
diff --git a/sequencer.h b/sequencer.h
index 82b79fd1e8..4f5ea2d818 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -46,6 +46,7 @@ struct replay_opts {
int no_commit;
int signoff;
int reviewby;
+ struct strvec trailer_args;
int allow_ff;
int allow_rerere_auto;
int allow_empty;
@@ -88,6 +89,7 @@ struct replay_opts {
.action = -1, \
.xopts = STRVEC_INIT, \
.ctx = replay_ctx_new(), \
+ .trailer_args = STRVEC_INIT, \
}
/*
diff --git a/t/meson.build b/t/meson.build
index 327fa461fd..fc4b64fca1 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -393,6 +393,7 @@ integration_tests = [
't3437-rebase-fixup-options.sh',
't3438-rebase-broken-files.sh',
't3439-rebase-reviewby.sh',
+ 't3440-rebase-trailer.sh',
't3500-cherry.sh',
't3501-revert-cherry-pick.sh',
't3502-cherry-pick-merge.sh',
diff --git a/t/t3440-rebase-trailer.sh b/t/t3440-rebase-trailer.sh
new file mode 100755
index 0000000000..6dc08e9633
--- /dev/null
+++ b/t/t3440-rebase-trailer.sh
@@ -0,0 +1,108 @@
+#!/bin/sh
+#
+
+test_description='git rebase --trailer integration tests
+We verify that --trailer on the merge/interactive/exec/root backends,
+and that it is rejected early when the apply backend is requested.'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-rebase.sh # test_commit_message, helpers
+
+############################################################################
+# 1. repository setup
+############################################################################
+
+test_expect_success 'setup repo with a small history' '
+ git commit --allow-empty -m "Initial empty commit" &&
+ test_commit first file a &&
+ test_commit second file &&
+ git checkout -b conflict-branch first &&
+ test_commit file-2 file-2 &&
+ test_commit conflict file &&
+ test_commit third file &&
+ ident="$GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>"
+'
+
+create_expect () {
+ cat >"$1" <<-EOF
+ $2
+
+ Reviewed-by: Dev <dev@xxxxxxxxxxx>
+ EOF
+}
+# golden files:
+create_expect initial-signed "Initial empty commit"
+create_expect first-signed "first"
+create_expect second-signed "second"
+create_expect file2-signed "file-2"
+create_expect third-signed "third"
+create_expect conflict-signed "conflict"
+
+############################################################################
+# 2. explicitly reject --apply + --trailer
+############################################################################
+
+test_expect_success 'apply backend is rejected when --trailer is given' '
+ git reset --hard third &&
+ git tag before-apply &&
+ test_expect_code 128 \
+ git rebase --apply --trailer "Reviewed-by: Dev <dev@xxxxxxxxxxx>" \
+ HEAD^ &&
+ git diff --quiet before-apply..HEAD # prove nothing moved
+'
+
+############################################################################
+# 3. --no‑op: same range, no changes
+############################################################################
+
+test_expect_success '--trailer without range change is a no‑op' '
+ git checkout main &&
+ git tag before-noop &&
+ git rebase --trailer "Reviewed-by: Dev <dev@xxxxxxxxxxx>" HEAD &&
+ git diff --quiet before-noop..HEAD
+'
+
+############################################################################
+# 4. merge backend (-m), conflict resolution path
+############################################################################
+
+test_expect_success 'rebase -m --trailer adds trailer after conflicts' '
+ git reset --hard third &&
+ test_must_fail git rebase -m \
+ --trailer "Reviewed-by: Dev <dev@xxxxxxxxxxx>" \
+ second third &&
+ git checkout --theirs file &&
+ git add file &&
+ GIT_EDITOR=: git rebase --continue &&
+ git show --no-patch --pretty=format:%B HEAD~2 >actual &&
+ test_cmp file2-signed actual
+'
+
+############################################################################
+# 5. --exec path
+############################################################################
+
+test_expect_success 'rebase --exec --trailer adds trailer' '
+ test_when_finished "rm -f touched" &&
+ git rebase --exec "touch touched" \
+ --trailer "Reviewed-by: Dev <dev@xxxxxxxxxxx>" \
+ first^ first &&
+ test_path_is_file touched &&
+ test_commit_message HEAD first-signed
+'
+
+############################################################################
+# 6. --root path
+############################################################################
+
+test_expect_success 'rebase --root --trailer updates every commit' '
+ git checkout first &&
+ git rebase --root --keep-empty \
+ --trailer "Reviewed-by: Dev <dev@xxxxxxxxxxx>" &&
+ test_commit_message HEAD first-signed &&
+ test_commit_message HEAD^ initial-signed
+'
+test_done
--
2.49.0
