Hint Rewrite @subst_lift4 (*@subst_lift4'*) @subst_lift4C : subst.

Lemma bool_val_notbool_ptr:
forall v t m,
match t with Tpointer _ _ => True | _ => False end ->
(Cop.bool_val (force_val (Cop.sem_notbool v t m)) type_bool m = Some true)
= (v = nullval).