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_norepet: forall vl G, list_norepet (map (@fst _ _) vl) -> match_fdecs vl G -> list_norepet (map (@fst _ _) G).