1 typedef struct x
2 {
3   struct x *type;
4   struct x *chain;
5   struct x *value;
6 } *tree;
7 
8 int
func(new,old)9 func (new, old)
10      register tree new, old;
11 {
12   if (old->type == 0 || new->type == 0)
13     {
14       register tree t = old->type;
15       if (t == 0)
16 	t = new->type;
17       for (; t; t = t->chain )
18 	if (t->value)
19 	  return 1;
20     }
21   return 0;
22 }
23