Hint Extern 2 (field_compatible _ (StructField _ :: _) _) =>
(apply field_compatible_cons; split; [ apply compute_in_members_e; reflexivity | ])
: field_compatible.

(* Specifications: *)
Lemma field_compatible_nullval: forall CS t f P,
@field_compatible CS t f nullval -> P.
Lemma field_compatible_nullval1:
forall (CS: compspecs) t fld p,
@field_compatible CS t fld p -> p <> nullval.
Lemma field_compatible_nullval2:
forall (CS: compspecs) t fld p,
@field_compatible CS t fld p -> nullval <> p.