An option can't exclude itself, so "abc[-ab][!abc]" with "command -a -b"

shouldn't segfault falling off the end of the list trying to report a
nonexistent error condition.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/args.c b/lib/args.c
index e6378beb..00932de9 100644
--- a/lib/args.c
+++ b/lib/args.c
@@ -159,11 +159,11 @@ static int gotflag(struct getoptflagstate *gof, struct opts *opt)
     struct opts *bad;
     unsigned i = 1;
 
-    for (bad=gof->opts, i=1; ;bad = bad->next, i<<=1) {
+    for (bad=gof->opts, i=1; bad ;bad = bad->next, i<<=1) {
       if (opt == bad || !(i & toys.optflags)) continue;
       if (toys.optflags & bad->dex[2]) break;
     }
-    help_exit("No '%c' with '%c'", opt->c, bad->c);
+    if (bad) help_exit("No '%c' with '%c'", opt->c, bad->c);
   }
 
   // Does this option take an argument?