`with recursive` as a subquery fails

create table r (

    src int primary key,

    tgt int

);

insert into r (src, tgt) values

  (2, 1),(3, 1),(4, 2),(5, 2),(6, 3),(7, 3),(8, 4),(9, 5);

(select src, tgt

 from r

)

union

(with recursive

      TransitiveClosure as (select  src, tgt

                            from r

                            union

                            (select

                                   TransitiveClosure.src as src,

                                   r.tgt as tgt

                            from TransitiveClosure,

                                 r

                            where r.src = TransitiveClosure.tgt)

                           )

 select src, tgt from TransitiveClosure

);