Definition compute_legal_nested_field0 (t: type) (gfs: list gfield) : list Prop :=
match gfs with
| nil => nil
| gf :: gfs0 =>
match (nested_field_type t gfs0), gf with
| Tarray _ n _, ArraySubsc i =>
(0 <= i <= n) :: compute_legal_nested_field t gfs0
| Tstruct id _, StructField i =>
if compute_in_members i (co_members (get_co id)) then compute_legal_nested_field t gfs else False :: nil
| Tunion id _, UnionField i =>
if compute_in_members i (co_members (get_co id)) then compute_legal_nested_field t gfs else False :: nil
| _, _ => False :: nil
end
end.

Lemma compute_legal_nested_field0_spec':
forall t gfs,
Forall Datatypes.id (compute_legal_nested_field0 t gfs) ->
legal_nested_field0 t gfs.