sequencer: make commit options more extensible

So far every time we need to tweak the behaviour of run_git_commit()
we have been adding a "int" parameter to it.  As the function gains
parameters and different callsites having different needs, this is
becoming a maintenance burden.  When a new knob needs to be added to
address a specific need for a single callsite, all the other callsites
need to add a "no, I do not want anything special with respect to the
new knob" argument.

Consolidate the existing four parameters into a flag word to make it
more maintainable, as we will be adding a new one to the mix soon.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer.c

@@ -602,6 +602,11 @@ N_("you have staged changes in your working tree\n"
 "\n"
 "  git rebase --continue\n");
 
+#define ALLOW_EMPTY (1<<0)
+#define EDIT_MSG    (1<<1)
+#define AMEND_MSG   (1<<2)
+#define CLEANUP_MSG (1<<3)
+
 /*
  * If we are cherry-pick, and if the merge did not result in
  * hand-editing, we will hit this commit and inherit the original
@@ -615,8 +620,7 @@ N_("you have staged changes in your working tree\n"
  * author metadata.
  */
 static int run_git_commit(const char *defmsg, struct replay_opts *opts,
-			  int allow_empty, int edit, int amend,
+			  unsigned int flags)
-			  int cleanup_commit_message)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	const char *value;
@@ -624,7 +628,7 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
 	cmd.git_cmd = 1;
 
 	if (is_rebase_i(opts)) {
-		if (!edit) {
+		if (!(flags & EDIT_MSG)) {
 			cmd.stdout_to_stderr = 1;
 			cmd.err = -1;
 		}
@@ -640,7 +644,7 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
 	argv_array_push(&cmd.args, "commit");
 	argv_array_push(&cmd.args, "-n");
 
-	if (amend)
+	if ((flags & AMEND_MSG))
 		argv_array_push(&cmd.args, "--amend");
 	if (opts->gpg_sign)
 		argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
@@ -648,16 +652,16 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
 		argv_array_push(&cmd.args, "-s");
 	if (defmsg)
 		argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
-	if (cleanup_commit_message)
+	if ((flags & CLEANUP_MSG))
 		argv_array_push(&cmd.args, "--cleanup=strip");
-	if (edit)
+	if ((flags & EDIT_MSG))
 		argv_array_push(&cmd.args, "-e");
-	else if (!cleanup_commit_message &&
+	else if (!(flags & CLEANUP_MSG) &&
 		 !opts->signoff && !opts->record_origin &&
 		 git_config_get_value("commit.cleanup", &value))
 		argv_array_push(&cmd.args, "--cleanup=verbatim");
 
-	if (allow_empty)
+	if ((flags & ALLOW_EMPTY))
 		argv_array_push(&cmd.args, "--allow-empty");
 
 	if (opts->allow_empty_message)
@@ -926,14 +930,14 @@ static void record_in_rewritten(struct object_id *oid,
 static int do_pick_commit(enum todo_command command, struct commit *commit,
 		struct replay_opts *opts, int final_fixup)
 {
-	int edit = opts->edit, cleanup_commit_message = 0;
+	unsigned int flags = opts->edit ? EDIT_MSG : 0;
-	const char *msg_file = edit ? NULL : git_path_merge_msg();
+	const char *msg_file = opts->edit ? NULL : git_path_merge_msg();
 	unsigned char head[20];
 	struct commit *base, *next, *parent;
 	const char *base_label, *next_label;
 	struct commit_message msg = { NULL, NULL, NULL, NULL };
 	struct strbuf msgbuf = STRBUF_INIT;
-	int res, unborn = 0, amend = 0, allow = 0;
+	int res, unborn = 0, allow;
 
 	if (opts->no_commit) {
 		/*
@@ -991,7 +995,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 			opts);
 		if (res || command != TODO_REWORD)
 			goto leave;
-		edit = amend = 1;
+		flags |= EDIT_MSG | AMEND_MSG;
 		msg_file = NULL;
 		goto fast_forward_edit;
 	}
@@ -1046,15 +1050,15 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 	}
 
 	if (command == TODO_REWORD)
-		edit = 1;
+		flags |= EDIT_MSG;
 	else if (is_fixup(command)) {
 		if (update_squash_messages(command, commit, opts))
 			return -1;
-		amend = 1;
+		flags |= AMEND_MSG;
 		if (!final_fixup)
 			msg_file = rebase_path_squash_msg();
 		else if (file_exists(rebase_path_fixup_msg())) {
-			cleanup_commit_message = 1;
+			flags |= CLEANUP_MSG;
 			msg_file = rebase_path_fixup_msg();
 		} else {
 			const char *dest = git_path("SQUASH_MSG");
@@ -1064,7 +1068,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 					     rebase_path_squash_msg(), dest);
 			unlink(git_path("MERGE_MSG"));
 			msg_file = dest;
-			edit = 1;
+			flags |= EDIT_MSG;
 		}
 	}
 
@@ -1123,11 +1127,11 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 	if (allow < 0) {
 		res = allow;
 		goto leave;
-	}
+	} else if (allow)
+		flags |= ALLOW_EMPTY;
 	if (!opts->no_commit)
 fast_forward_edit:
-		res = run_git_commit(msg_file, opts, allow, edit, amend,
+		res = run_git_commit(msg_file, opts, flags);
-				     cleanup_commit_message);
 
 	if (!res && final_fixup) {
 		unlink(rebase_path_fixup_msg());
@@ -2154,7 +2158,7 @@ static int continue_single_pick(void)
 
 static int commit_staged_changes(struct replay_opts *opts)
 {
-	int amend = 0;
+	unsigned int flags = ALLOW_EMPTY | EDIT_MSG;
 
 	if (has_unstaged_changes(1))
 		return error(_("cannot rebase: You have unstaged changes."));
@@ -2184,10 +2188,10 @@ static int commit_staged_changes(struct replay_opts *opts)
 				       "--continue' again."));
 
 		strbuf_release(&rev);
-		amend = 1;
+		flags |= AMEND_MSG;
 	}
 
-	if (run_git_commit(rebase_path_message(), opts, 1, 1, amend, 0))
+	if (run_git_commit(rebase_path_message(), opts, flags))
 		return error(_("could not commit staged changes."));
 	unlink(rebase_path_amend());
 	return 0;