Set Returning Functions and array_agg()

Hi,

I have a UDF (written in C) that returns SETOF RECORD of an anonymous record type

(defined via OUT parameters). I'm trying to use array_agg() to transform its output to

an array:

pg_dev=# SELECT array_agg(col1(my_setof_record_returning_func()));

ERROR:  set-valued function called in context that cannot accept a set

Can somebody explain why I get the error message? Presumably the parser is deciding that

the expression provided to array_agg() is a set, based on my_setof_record_returning_func()'s

definition. But shouldn't the column selection (or equivalent column-as-func-call notation) supply

the expected context to array_agg()?

Thanks.