Dominique Devienne <ddevienne@gmail.com> writes:
> But still, arg names are not part of the signature.
> So they should be checked after the fact.
No, that's not how it works. David's comment about signature
reflects the fact that the primary key of pg_proc is name +
schema + input argument types. Arg names are independent of
that and actually have to be checked before we consider argument
type matching, because they help determine which input argument
is which.
(There was considerable debate when we added output arguments
and argument names about whether pg_proc's primary key should
be extended. We ended up not, but it was a judgment call.)
regards, tom lane