(* Lemma nonexpansive_2super_non_expansive: forall {A B: Type} (F: (A -> B -> mpred) -> mpred), (forall a b, nonexpansive (fun Q => F P Q)) -> (forall Q, nonexpansive (fun P => F P Q)) -> forall P Q n, approx n (F P Q) = approx n (F (approx n P) (approx n Q)). *)
Definition acquire_arg_type: rmaps.TypeTree := rmaps.ProdType (rmaps.ConstType (val * share)) rmaps.Mpred.
Definition acquire_pre: val * share * mpred -> environ -> mpred :=
fun args =>
match args with
| (v, sh, R) =>
PROP (readable_share sh)
LOCAL (temp _lock v)
SEP (lock_inv sh v R)
end.
Notation acquire_post :=
(fun args =>
match args with
| (v, sh, R) =>
PROP ()
LOCAL ()
SEP (lock_inv sh v R; R)
end).

Lemma NP_acquire_post: @super_non_expansive acquire_arg_type (fun _ => acquire_post).
Definition acquire_spec: funspec := mk_funspec
((_lock OF tptr Tvoid)%formals :: nil, tvoid)
cc_default
acquire_arg_type
(fun _ => acquire_pre)
(fun _ => acquire_post)
NP_acquire_pre
NP_acquire_post
.