Set Returning Function problem

Hi,

I noticed what i think is a weird behaviour with SRFs. When I use them
in a SELECT clause, and the SRF returns no rows, the query returns no
rows too, when I think it should return an a null column. I'm posting an
example below:

test=> CREATE TABLE foo (cod SERIAL, bar TEXT);
NOTICE: CREATE TABLE will create implicit sequence "foo_cod_seq" for
"serial" column "foo.cod"
CREATE TABLE

test=>
test=> INSERT INTO foo (bar) VALUES ('asdasd');
INSERT 60702758 1

test=> CREATE OR REPLACE FUNCTION srf_foo(INTEGER)
test-> RETURNS setof foo
test-> AS '
test'> SELECT * FROM foo WHERE cod = $1;
test'> ' LANGUAGE 'SQL';
CREATE FUNCTION

test=>
test=> SELECT cod, (srf_foo(cod)).bar
test-> FROM foo;
cod | bar
-----+--------
1 | asdasd
(1 record)

test=>
test=> SELECT cod, (srf_foo(50)).bar
test-> FROM foo;
cod | bar
-----+-----
(0 records)

Thanks in advance,

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