Re: BUG #18463: Possible bug in stored procedures with polymorphic OUT parameters

I wrote:
> It looks like we'd have to teach resolve_polymorphic_tupdesc how
> to get argument types out of a CallExpr, so that does not lead
> to an entirely trivial fix, but it's surely possible.

> Maybe it'd be better to not try to use build_function_result_tupdesc_t
> here at all. It looks to me like the output argument list in the
> CallStmt is already fully polymorphically resolved, so we could just
> build a tupdesc based on that and probably save a lot of work.

Some experimentation showed that we need to return the correct
output column names in this tupdesc, so continuing to use
build_function_result_tupdesc_t seems like the easiest path for that.
However, stmt->outargs does hold nodes of the correct resolved data
types, so overwriting the atttypid's from that produces a nicely
small patch, as attached.

regards, tom lane