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 ptr_eq_e': forall v1 v2 B,
(v1=v2 -> B) ->
(ptr_eq v1 v2 -> B).