I wrote:
> The thing I'm unhappy about is that "0" is being overloaded way too far
> as a function argument/result type in pg_proc. Currently it could mean:
> * unused position in proargtype array;
> * erroneous definition;
> * "C string" parameter to a type input function (but, for who
> knows what reason, C string outputs from type-output functions
> are represented differently);
> * user proc returning some kind of tuple;
> * user proc returning nothing in particular;
> and who knows what else.
Almost forgot:* function accepting any data type whatever
(I think COUNT() is the only one at present).
regards, tom lane