Need to clear stack region for local variables in eval; fix #3844

mrbgems/mruby-eval/src/eval.c

@@ -273,13 +273,17 @@ create_proc_from_string(mrb_state *mrb, char *s, mrb_int len, mrb_value binding,
 static mrb_value
 exec_irep(mrb_state *mrb, mrb_value self, struct RProc *proc)
 {
+  /* no argument passed from eval() */
+  mrb->c->ci->argc = 0;
   if (mrb->c->ci->acc < 0) {
-    mrb_value ret = mrb_top_run(mrb, proc, mrb->c->stack[0], 0);
+    mrb_value ret = mrb_top_run(mrb, proc, self, 0);
     if (mrb->exc) {
       mrb_exc_raise(mrb, mrb_obj_value(mrb->exc));
     }
     return ret;
   }
+  /* clear block */
+  mrb->c->stack[1] = mrb_nil_value();
   return mrb_exec_irep(mrb, self, proc);
 }
 

src/vm.c

@@ -491,6 +491,7 @@ mrb_value
 mrb_exec_irep(mrb_state *mrb, mrb_value self, struct RProc *p)
 {
   mrb_callinfo *ci = mrb->c->ci;
+  int keep;
 
   mrb->c->stack[0] = self;
   ci->proc = p;
@@ -499,7 +500,15 @@ mrb_exec_irep(mrb_state *mrb, mrb_value self, struct RProc *p)
     return p->body.func(mrb, self);
   }
   ci->nregs = p->body.irep->nregs;
-  stack_extend(mrb, (ci->argc < 0 && ci->nregs < 3) ? 3 : ci->nregs);
+  if (ci->argc < 0) keep = 3;
+  else keep = ci->argc + 1;
+  if (ci->argc < keep) {
+    stack_extend(mrb, keep);
+  }
+  else {
+    stack_extend(mrb, ci->argc);
+    stack_clear(mrb->c->stack+keep, ci->nregs-keep);
+  }
 
   ci = cipush(mrb);
   ci->nregs = 0;