BUG #6551: PL/pgSQL: GET DIAGNOSTICS not working for first OUT parameter

The following bug has been logged on the website:

Bug reference:      6551
Logged by:          Adam Buraczewski
Email address:      aburacze@gmail.com
PostgreSQL version: 9.1.3
Operating system:   Linux (Fedora 16)
Description:=20=20=20=20=20=20=20=20

Hi!

I have just found strange behaviour of PL/pgSQL in case of using OUT
parameters and GET DIAGNOSTICS var =3D ROW_COUNT (PostgreSQL 9.1.3). Here i=
s a
self-contained example:

create table t (c integer);

create function p(out x1 integer, out x2 integer, out x3 integer)
as $$
begin
    insert into t values (1);
    get diagnostics x1 =3D row_count;
    insert into t values (2);
    get diagnostics x2 =3D row_count;
    insert into t values (3);
    get diagnostics x3 =3D row_count;
end;
$$ language plpgsql;

select * from p();

 x1 | x2 | x3=20
----+----+----
    |  1 |  1

Why x1 is NULL instead of the value 1? I found a workaround: declare a
temporary variable inside the function then assign ROW_COUNT to that
variable and then assign temporary variable to the OUT parameter. It works
but probably is not the solution one could expect:

create function p_workaround(out x1 integer, out x2 integer, out x3
integer)
as $$
declare
    tmpvar integer;
begin
    insert into t values (1);
    get diagnostics tmpvar =3D row_count;
    x1 :=3D tmpvar;
    insert into t values (2);
    get diagnostics x2 =3D row_count;
    insert into t values (3);
    get diagnostics x3 =3D row_count;
end;
$$ language plpgsql;

select * from p_workaround();

 x1 | x2 | x3=20
----+----+----
  1 |  1 |  1

Best regards,
Adam