Show usage and exit non-zero for unsupported option in lefty

Towards https://gitlab.com/graphviz/graphviz/-/issues/1843.

diff --git a/cmd/lefty/lefty.c b/cmd/lefty/lefty.c
index e49eaa7acf56ba6db9f1b7166e81ee92042bccf5..25cf1eccde6698e6ab4d561fc0008bcc83d7c0a2 100644 (file)
--- a/cmd/lefty/lefty.c
+++ b/cmd/lefty/lefty.c
@@ -471,7 +471,8 @@ static void processargs (int argc, char *argv[]) {
                 fclose(fp);
             fp = stdin;
         } else if (argv[0][0] == '-') {
-            fprintf (stderr, "option %s unrecognized - ignored\n", argv[0]);
+            fprintf (stderr, "option %s unrecognized\n", argv[0]);
+            usage(1);
         }
         else {
             if (fp != NULL && fp != stdin)