why can't plpgsql return a row-expression?

Hi,

PL/pgsql seems to have a strange restriction regarding "RETURN".
Normally, you can write "RETURN <expression>". But if the function
returns a row type, then you can only write "RETURN variable" or
"RETURN NULL".

rhaas=# create type xyz as (a int, b int);
CREATE TYPE
rhaas=# select row(1,2)::xyz;
row
-------
(1,2)
(1 row)

rhaas=# create or replace function return_xyz() returns xyz as $$
rhaas$# begin
rhaas$# return row(1,2)::xyz;
rhaas$# end$$ language plpgsql;
ERROR: RETURN must specify a record or row variable in function returning row
LINE 3: return row(1,2)::xyz;
^

Off the top of my head, I can't think of any reason for this
restriction, nor can I find any code comments or anything in the
commit log which explains the reason for it. Does anyone know why we
don't allow this?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company