Check arg count when expanding defsymacro.

* eval.c (do_expand): Throw error if defsymacro form
isn't a list of three elements, just like defparm
and defparml do.

1 files changed, 3 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index c5935cc1..341dbcff 100644
--- a/eval.c
+++ b/eval.c
@@ -3435,6 +3435,9 @@ static val do_expand(val form, val menv)
       val init_ex = expand(init, menv);
       val form_ex = form;
 
+      if (sym == defsymacro_s && length(form) != three)
+        eval_error(form, lit("~s: two arguments expected"), sym, nao);
+
       if (init != init_ex)
         form_ex = rlcp(cons(sym, cons(name, cons(init_ex, nil))), form);