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).