Definition prog_var_block (rho: environ) (il: list ident) (b: block) : Prop :=
  Exists (fun id => match ge_of rho id with Some b' => b'=b | _ => False end) il.

Lemma match_fdecs_in: forall i vl G, In i (map (@fst _ _) G) -> match_fdecs vl G -> In i (map (@fst _ _) vl).