From 99d6eeb8fc25f8a969b40e13623f1023d11074d8 Mon Sep 17 00:00:00 2001
From: nicm <nicm@openbsd.org>
Date: Thu, 3 Mar 2022 08:24:12 +0000
Subject: [PATCH] Allow optional arguments.

---
 usr.bin/tmux/arguments.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/usr.bin/tmux/arguments.c b/usr.bin/tmux/arguments.c
index ce3313801f5..8b1f9c60786 100644
--- a/usr.bin/tmux/arguments.c
+++ b/usr.bin/tmux/arguments.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: arguments.c,v 1.52 2021/11/02 10:57:04 nicm Exp $ */
+/* $OpenBSD: arguments.c,v 1.53 2022/03/03 08:24:12 nicm Exp $ */
 
 /*
  * Copyright (c) 2010 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -131,8 +131,9 @@ args_parse(const struct args_parse *parse, struct args_value *values,
 	u_int			 i;
 	enum args_parse_type	 type;
 	struct args_value	*value, *new;
-	u_char			 flag, argument;
+	u_char			 flag;
 	const char		*found, *string, *s;
+	int			 optional_argument;
 
 	if (count == 0)
 		return (args_create());
@@ -169,18 +170,27 @@ args_parse(const struct args_parse *parse, struct args_value *values,
 				args_free(args);
 				return (NULL);
 			}
-			argument = *++found;
-			if (argument != ':') {
+			if (*++found != ':') {
 				log_debug("%s: -%c", __func__, flag);
 				args_set(args, flag, NULL);
 				continue;
 			}
+			if (*found == ':') {
+				optional_argument = 1;
+				found++;
+			}
 			new = xcalloc(1, sizeof *new);
 			if (*string != '\0') {
 				new->type = ARGS_STRING;
 				new->string = xstrdup(string);
 			} else {
 				if (i == count) {
+					if (optional_argument) {
+						log_debug("%s: -%c", __func__,
+						    flag);
+						args_set(args, flag, NULL);
+						continue;
+					}
 					xasprintf(cause,
 					    "-%c expects an argument",
 					    flag);
-- 
2.20.1