commit: allow -c/-C for all kinds of --fixup

The previous commit allowed -m and -F for all --fixup variations. The -c/-C flags were blocked by the same higher-layer incompatibility check that previously caught -F, namely die_for_incompatible_opt4() grouping them with --fixup. Drop --fixup from that check and route the resolved commit through prepare_amend_commit() in the fixup path, mirroring the no-message-source behaviour of --fixup=amend. With this in place, -m/-F/-c/-C all behave consistently across the plain, amend, and reword --fixup forms. Signed-off-by: Erik Cervin-Edin <erik@cervined.in> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Erik Cervin-Edin committed May 26, 2026 at 12:47 UTC f1c098502df421cb0c96bb168044c278ef9d7990
3 files changed +71 -11
Documentation/git-commit.adoc
+5 -4
@@ -102,8 +102,8 @@ include::diff-context-options.adoc[]
102 +
103 The commit created by plain `--fixup=<commit>` has a title
104 composed of "fixup!" followed by the title of _<commit>_,
105 -and is recognized specially by `git rebase --autosquash`. The `-m`
106 -or `-F` option may be used to supplement the log message
105 +and is recognized specially by `git rebase --autosquash`. The `-m`,
106 +`-F`, `-C`, or `-c` option may be used to supplement the log message
107 of the created commit, but the additional commentary will be thrown
108 away once the "fixup!" commit is squashed into _<commit>_ by
109 `git rebase --autosquash`.
@@ -112,8 +112,9 @@ The commit created by `--fixup=amend:<commit>` is similar but its
112 title is instead prefixed with "amend!". The log message of
113 _<commit>_ is copied into the log message of the "amend!" commit and
114 opened in an editor so it can be refined. The replacement message may
115 -also be supplied directly using `-m` or `-F`, bypassing the
116 -need to open an editor. When `git rebase
115 +also be supplied directly using `-m`, `-F`, or `-C`, bypassing the
116 +need to open an editor, or using `-c` to open the editor pre-populated
117 +with the referenced commit's message. When `git rebase
118 --autosquash` squashes the "amend!" commit into _<commit>_, the log
119 message of _<commit>_ is replaced by the refined log message from the
120 "amend!" commit. It is an error for the "amend!" commit's log message
builtin/commit.c
+9 -4
@@ -837,9 +837,9 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
837 hook_arg1 = "message";
838
839 /*
840 - * Only `-m` and `-F` are handled here. `-c`/`-C` are
841 - * incompatible with --fixup and have already errored out
842 - * during option parsing.
840 + * `-m`, `-F`, `-C`, and `-c` provide the message body.
841 + * If none was given and this is an amend, use the target
842 + * commit's body instead.
843 */
844 if (have_option_m) {
845 strbuf_addbuf(&sb, &message);
@@ -851,6 +851,11 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
851 } else if (logfile) {
852 if (strbuf_read_file(&sb, logfile, 0) < 0)
853 die_errno(_("could not read log file '%s'"), logfile);
854 + } else if (use_message) {
855 + struct commit *c = lookup_commit_reference_by_name(use_message);
856 + if (!c)
857 + die(_("could not lookup commit '%s'"), use_message);
858 + prepare_amend_commit(c, &sb, &ctx);
859 } else if (!strcmp(fixup_prefix, "amend")) {
860 prepare_amend_commit(commit, &sb, &ctx);
861 }
@@ -1341,7 +1346,7 @@ static int parse_and_validate_options(int argc, const char *argv[],
1346 die(_("options '%s' and '%s' cannot be used together"), "--squash", "--fixup");
1347 die_for_incompatible_opt3(!!use_message, "-C",
1348 !!edit_message, "-c",
1344 - !!fixup_message, "--fixup");
1349 + !!logfile, "-F");
1350 die_for_incompatible_opt4(have_option_m, "-m",
1351 !!edit_message, "-c",
1352 !!use_message, "-C",
t/t7500-commit-template-squash-signoff.sh
+57 -3
@@ -492,6 +492,62 @@ test_expect_success 'commit --fixup works with -F' '
492 EOF
493 '
494
495 +test_expect_success 'commit --fixup works with -C' '
496 + commit_for_rebase_autosquash_setup &&
497 + git commit --fixup HEAD~ -C HEAD &&
498 + test_commit_message HEAD <<-EOF
499 + fixup! $(git log -1 --format=%s HEAD~2)
500 +
501 + $(get_commit_msg HEAD~)
502 + EOF
503 +'
504 +
505 +test_expect_success 'commit --fixup=amend: works with -c' '
506 + commit_for_rebase_autosquash_setup &&
507 + test_set_editor : &&
508 + git commit --fixup=amend:HEAD -c HEAD~ &&
509 + test_commit_message HEAD <<-EOF
510 + amend! intermediate commit
511 +
512 + target message subject line
513 +
514 + target message body line 1
515 + target message body line 2
516 + EOF
517 +'
518 +
519 +test_expect_success 'commit --fixup=amend:HEAD with -C HEAD and without have the same message' '
520 + commit_for_rebase_autosquash_setup &&
521 + start=$(git rev-parse HEAD) &&
522 +
523 + git commit --fixup=amend:HEAD -C HEAD &&
524 + git commit --fixup=amend:HEAD -C HEAD &&
525 + git log -1 --pretty=%B >with-c &&
526 +
527 + git reset --hard "$start" &&
528 + test_set_editor : &&
529 + git commit --fixup=amend:HEAD &&
530 + git commit --fixup=amend:HEAD &&
531 + git log -1 --pretty=%B >without-c &&
532 +
533 + test_cmp with-c without-c
534 +'
535 +
536 +test_expect_success 'commit --fixup=amend: with -C copies full subject + body of squash commit' '
537 + commit_for_rebase_autosquash_setup &&
538 + git commit --squash HEAD~ -m "inner body" &&
539 + echo "extra" >>foo &&
540 + git add foo &&
541 + git commit --fixup=amend:HEAD -C HEAD &&
542 + test_commit_message HEAD <<-EOF
543 + amend! squash! $(git log -1 --format=%s HEAD~3)
544 +
545 + squash! $(git log -1 --format=%s HEAD~3)
546 +
547 + inner body
548 + EOF
549 +'
550 +
551 test_expect_success 'commit --fixup=reword: works with -F' '
552 commit_for_rebase_autosquash_setup &&
553 echo "message from file" >msgfile &&
@@ -553,9 +609,7 @@ test_expect_success 'invalid message options when using --fixup' '
609 echo changes >>foo &&
610 echo "message" >log &&
611 git add foo &&
556 - test_must_fail git commit --fixup HEAD~1 --squash HEAD~2 &&
557 - test_must_fail git commit --fixup HEAD~1 -C HEAD~2 &&
558 - test_must_fail git commit --fixup HEAD~1 -c HEAD~2
612 + test_must_fail git commit --fixup HEAD~1 --squash HEAD~2
613 '
614
615 cat >expected-template <<EOF