Subject: Re: [PATCH] rebase: write script before initializing state

From: Junio C Hamano <[email-masked]>
Date: Mon, 09 Jun 2025 16:03:13 -0700

Øystein Walle <[email-masked]> writes:

> ...
> By attempting to write the rebase script before initializing the state
> this potential scenario is avoided.
> ---

Missing sign-off.

> The diff looks perhaps more messy than required. The only required
> change is the filling in of make_script_args and the call to
> sequencer_make_script() above the call to init_basic_state(). But then
> the `if (ret)` looks out of place, and moving that up means adding `goto
> cleanup` which means the code that was previously the else case can be
> dedented.

"git show --histogram" may do a lot better job than the default
algorithm used by "git show" for this patch.

diff --git a/builtin/rebase.c b/builtin/rebase.c
index d4715ed35d..06da8e4f36 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -283,53 +283,53 @@ static int init_basic_state(struct replay_opts *opts, const char *head_name,
 static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)
 {
 	int ret = -1;
 	char *revisions = NULL, *shortrevisions = NULL;
 	struct strvec make_script_args = STRVEC_INIT;
 	struct todo_list todo_list = TODO_LIST_INIT;
 	struct replay_opts replay = get_replay_opts(opts);
 
 	if (get_revision_ranges(opts->upstream, opts->onto, &opts->orig_head->object.oid,
 				&revisions, &shortrevisions))
 		goto cleanup;
 
+	strvec_pushl(&make_script_args, "", revisions, NULL);
+	if (opts->restrict_revision)
+		strvec_pushf(&make_script_args, "^%s",
+			     oid_to_hex(&opts->restrict_revision->object.oid));
+
+	ret = sequencer_make_script(the_repository, &todo_list.buf,
+				    make_script_args.nr, make_script_args.v,
+				    flags);
+	if (ret) {
+		error(_("could not generate todo list"));
+		goto cleanup;
+	}
+
 	if (init_basic_state(&replay,
 			     opts->head_name ? opts->head_name : "detached HEAD",
 			     opts->onto, &opts->orig_head->object.oid))
 		goto cleanup;
 
 	if (!opts->upstream && opts->squash_onto)
 		write_file(path_squash_onto(), "%s\n",
 			   oid_to_hex(opts->squash_onto));
 
-	strvec_pushl(&make_script_args, "", revisions, NULL);
-	if (opts->restrict_revision)
-		strvec_pushf(&make_script_args, "^%s",
-			     oid_to_hex(&opts->restrict_revision->object.oid));
+	discard_index(the_repository->index);
+	if (todo_list_parse_insn_buffer(the_repository, &replay,
+					todo_list.buf.buf, &todo_list))
+		BUG("unusable todo list");
 
-	ret = sequencer_make_script(the_repository, &todo_list.buf,
-				    make_script_args.nr, make_script_args.v,
-				    flags);
-
-	if (ret)
-		error(_("could not generate todo list"));
-	else {
-		discard_index(the_repository->index);
-		if (todo_list_parse_insn_buffer(the_repository, &replay,
-						todo_list.buf.buf, &todo_list))
-			BUG("unusable todo list");
-
-		ret = complete_action(the_repository, &replay, flags,
-			shortrevisions, opts->onto_name, opts->onto,
-			&opts->orig_head->object.oid, &opts->exec,
-			opts->autosquash, opts->update_refs, &todo_list);
-	}
+	ret = complete_action(the_repository, &replay, flags,
+		shortrevisions, opts->onto_name, opts->onto,
+		&opts->orig_head->object.oid, &opts->exec,
+		opts->autosquash, opts->update_refs, &todo_list);
 
 cleanup:
 	replay_opts_release(&replay);
 	free(revisions);
 	free(shortrevisions);
 	todo_list_release(&todo_list);
 	strvec_clear(&make_script_args);
 
 	return ret;
 }
diff --git a/t/t3415-rebase-autosquash.sh b/t/t3415-rebase-autosquash.sh
index fcc40d6fe1..d4c624b841 100755
--- a/t/t3415-rebase-autosquash.sh
+++ b/t/t3415-rebase-autosquash.sh
@@ -394,6 +394,16 @@ test_expect_success 'autosquash with empty custom instructionFormat' '
 	)
 '
 
+test_expect_success 'autosquash with invalid custom instructionFormat' '
+	git reset --hard base &&
+	test_commit invalid-instructionFormat-test &&
+	(
+		test_must_fail git -c rebase.instructionFormat=blah \
+			rebase --autosquash  --force-rebase -i HEAD^ &&
+		test_path_is_missing .git/rebase-merge
+	)
+'
+
 set_backup_editor () {
 	write_script backup-editor.sh <<-\EOF
 	cp "$1" .git/backup-"$(basename "$1")"