(** Compatibility between a compilation environment and an address-taken set. *)
Definition compat_cenv (atk: VSet.t) (cenv: compilenv) : Prop :=
forall id, VSet.In id atk -> VSet.In id cenv -> False.

Lemma compat_cenv_for:
forall f, compat_cenv (addr_taken_stmt f.(fn_body)) (cenv_for f).