can not pass date to function correctly - postgresql

Question

CREATE or replace FUNCTION testing_lockstep(_id_arr int[], _counter_arr int[], d_date date)
RETURNS TABLE (uc__id int)
LANGUAGE plpgsql AS
$func$
DECLARE
_id int;
_counter int;
d_date date;
BEGIN
FOR _id, _counter IN
SELECT *
FROM unnest (_id_arr, _counter_arr) t -- !!
LOOP
RETURN QUERY
with orig_dataset as (
select a.uc_id, cr.imei,cr.points_geom ,cr.created_at as time_created
from campaign_routes cr
left join assets a on a.imei = cr.imei
where cr.created_at::date > d_date
)
select uc_id
from orig_dataset;
END LOOP;
END
$func$;
My function call is as follows:
SELECT * FROM testing_lockstep('{454,454}'::int[]
, '{2,3}'::int[], TO_DATE('2017-01-03','YYYY-MM-DD') );
The issue is I am getting a null result set, even though if I hardcode the same date in the function body, then I am getting correct results, i.e. if I write:
where cr.created_at::date > '2023-01-17'::date
then I am getting correct results.
Please note, in the main function body, I have ommited parts for the sake of brevity.

Answer 1

Apparently it is allowed to declare a variable with the same name as a parameter, that is than used instead of the parameter.
Simple remove the duplicated declaration of d_date from your function and it will start to work;)
CREATE or replace FUNCTION testing_lockstep(_id_arr int[], _counter_arr int[], d_date date)
RETURNS TABLE (uc__id int)
LANGUAGE plpgsql AS
$func$
DECLARE
_id int;
_counter int;
-- comment this out -->>>> d_date date;