Raise `ArgumentError` by `aspec` check; ref #4688

This is partial `aspec` check that only checks `MRB_ARGS_NONE()`.

2 files changed, 8 insertions, 0 deletions

diff --git a/src/class.c b/src/class.c
index ac0bb8ede..d037a8abb 100644
--- a/src/class.c
+++ b/src/class.c
@@ -470,6 +470,9 @@ mrb_define_method_id(mrb_state *mrb, struct RClass *c, mrb_sym mid, mrb_func_t f
   int ai = mrb_gc_arena_save(mrb);
 
   MRB_METHOD_FROM_FUNC(m, func);
+  if (aspec == MRB_ARGS_NONE()) {
+    MRB_METHOD_NOARG_SET(m);
+  }
   mrb_define_method_raw(mrb, c, mid, m);
   mrb_gc_arena_restore(mrb, ai);
 }
diff --git a/src/vm.c b/src/vm.c
index 8d233f291..449ea7b13 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -1435,6 +1435,11 @@ RETRY_TRY_BLOCK:
           ci->proc = p;
           recv = p->body.func(mrb, recv);
         }
+        else if (MRB_METHOD_NOARG_P(m) &&
+                 (argc > 0 || (argc == -1 && RARRAY_LEN(regs[1]) != 0))) {
+          argnum_error(mrb, 0);
+          goto L_RAISE;
+        }
         else {
           recv = MRB_METHOD_FUNC(m)(mrb, recv);
         }