Fixpoint iota_formals (i: ident) (tl: typelist) :=
match tl with
| Tcons t tl' => (i,t) :: iota_formals (i+1)%positive tl'
| Tnil => nil
end.
Ltac make_sequential :=
match goal with
| |- @semax _ _ _ _ _ (normal_ret_assert _) => idtac
| |- _ => apply sequential
end.

Lemma isptr_offset_val'': forall i p Q,
(isptr p -> Q) ->
(isptr (offset_val i p) -> Q).