From 871d90846fc38b116fc1dff75bbe5e2b262d1f54 Mon Sep 17 00:00:00 2001
From: David Caldwell <david@galvanix.com>
Date: Mon, 24 Sep 2018 23:21:11 +0000
Subject: [PATCH] Add a more helpful error message when unkown options are
 encountered

---
 docopt.go | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/docopt.go b/docopt.go
index c22feb7..a670cd3 100644
--- a/docopt.go
+++ b/docopt.go
@@ -181,7 +181,15 @@ func parse(doc string, argv []string, help bool, version string, optionsFirst bo
 		return
 	}
 
-	err = newUserError("")
+	if len(*left) > 0 {
+		var left_names []string
+		for _, l := range(*left) {
+			left_names = append(left_names, l.name)
+		}
+		err = newUserError(fmt.Sprintf("Unknown option(s): %s", strings.Join(left_names, ", ")))
+	} else {
+		err = newUserError("")
+	}
 	output = handleError(err, usage)
 	return
 }