PERFORM not working properly, please help..

I have a function A1 that returns setof records, and I use it in two ways:
1) from function A2, where I need results from A1
2) from function A3, where I don't need these results, all I need is to execute logic from A1

Here ale very simple versions of my functions:

CREATE OR REPLACE FUNCTION A1() RETURNS setof record AS $BODY$
begin
 -- some logic here
 return query select col from tab;
end;
$BODY$ LANGUAGE 'plpgsql';

CREATE OR REPLACE FUNCTION A2() RETURNS setof record AS $BODY$
begin
 -- some logic here
 return query select * from A1() as dummy ( x double precision);
end;
$BODY$ LANGUAGE 'plpgsql';

CREATE OR REPLACE FUNCTION A3() RETURNS VOID AS $BODY$
begin
 perform A1();
end;
$BODY$ LANGUAGE 'plpgsql';

And here are my function calls:
select * from A1() as(x double precision) --ok
select * from A2() as(x double precision) --ok
select * from A3(); --not ok, argh!

The last one generates error "set-valued function called in context that cannot accept a set". Why doesn't PERFORM work here? Thanks for help..