Fix dijkstra -? to actually print usage instead of error on macOS

Towards https://gitlab.com/graphviz/graphviz/-/issues/1852.

diff --git a/cmd/tools/dijkstra.c b/cmd/tools/dijkstra.c
index ddf5704e8d501c870cabcfab763bb1f505b3825f..2b3819380ff7b4d323a4ce7ee13821d9125c3c3d 100644 (file)
--- a/cmd/tools/dijkstra.c
+++ b/cmd/tools/dijkstra.c
@@ -261,7 +261,7 @@ static void init(int argc, char *argv[])
            doPath = 1;
            break;
        case '?':
-           if (optopt == '\0')
+           if (optopt == '\0' || optopt == '?')
                usage(0);
            else {
                fprintf(stderr, "%s: option -%c unrecognized\n",