Hint Rewrite @closed_wrt_subst_eval_expr using solve [auto 50 with closed] : subst.
Hint Rewrite @closed_wrt_subst_eval_lvalue using solve [auto 50 with closed] : subst.
Hint Unfold closed_wrt_modvars : closed.

Lemma closed_wrt_lift0C: forall {B} S (Q: B),
closed_wrt_vars S (@liftx (LiftEnviron B) Q).