Notation "'TYPE' A 'WITH'  x1 : t1 , x2 : t2 , x3 : t3 , x4 : t4 , x5 : t5 'PRE'  [ u , .. , v ] P 'POST' [ tz ] Q" :=
     (mk_funspec ((cons u%formals .. (cons v%formals nil) ..), tz) cc_default A
  (fun (ts: list Type) (x: t1*t2*t3*t4*t5) =>
     match x with (x1,x2,x3,x4,x5) => P%assert end)
  (fun (ts: list Type) (x: t1*t2*t3*t4*t5) =>
     match x with (x1,x2,x3,x4,x5) => Q%assert end) _ _)
            (at level 200, x1 at level 0, x2 at level 0, x3 at level 0, x4 at level 0, x5 at level 0,
             P at level 100, Q at level 100).Definition lock_sig := (ProdType (ConstType (share * val * val * val)) Mpred).

Lemma weak_precise_lock_R : forall R h v, predicates_hered.derives (weak_precise_mpred R && emp) (weak_precise_mpred (lock_R R h v) && emp).