Re: BUG #1723: array_cat() bug when passed empty array

I wrote:
> Actually, I would say the bug is exec_assign_value's.  There is nothing
> at all wrong with a function returning one of its input values; for
> example the smaller/larger functions all do that.

For that matter, you don't need a function at all:

regression=# create or replace function copyit(text) returns text as $$
regression$# declare tmp text;
regression$# begin
regression$#   tmp := $1;
regression$#   tmp := tmp;
regression$#   return tmp;
regression$# end$$ language plpgsql stable;
CREATE FUNCTION
regression=# select copyit('foo');
ERROR:  out of memory
DETAIL:  Failed on request of size 1065320319.
CONTEXT:  PL/pgSQL function "copyit" line 4 at assignment
regression=#

This makes it perfectly clear that the problem is that exec_assign_value
must copy the given value before it frees the old, just in case they're
the same.  (Hmm, I wonder if we can shortcircuit the whole thing ...)

            regards, tom lane