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

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

diff --git a/cmd/tools/gvpack.c b/cmd/tools/gvpack.c
index 598d838bf9e5f99184111ffceb1074893a51d897..b2de4bdd7d81f69a04aa80ee8914ff45abcde464 100644 (file)
--- a/cmd/tools/gvpack.c
+++ b/cmd/tools/gvpack.c
@@ -245,9 +245,11 @@ static void init(int argc, char *argv[], pack_info* pinfo)
        case '?':
            if (optopt == '?')
                usage(0);
-           else
+           else {
                fprintf(stderr,
-                       "gvpack: option -%c unrecognized - ignored\n", optopt);
+                       "gvpack: option -%c unrecognized\n", optopt);
+               usage(1);
+           }
            break;
        }
     }