Re: BUG #17066: Cache lookup failed when null (unknown) is passed as anycompatiblemultirange

On Thu, Jun 24, 2021 at 1:41 AM Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
> On Wed, Jun 23, 2021 at 6:31 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
> > On Tue, Jun 22, 2021 at 7:01 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
> > > On Tue, Jun 22, 2021 at 4:42 PM Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote:
> > > > On 2021-Jun-22, Neil Chen wrote:
> > > >
> > > > > Greetings,
> > > > >
> > > > > I tried to investigate the bug, but the complicated logic here completely
> > > > > messed up my mind...
> > > > >
> > > > > Anyway, this patch can fix it and make the regress test happy. But I think
> > > > > it's better to get the author's advice - I copied this email to Alvaro,
> > > > > hope it doesn't offend him...
> > > >
> > > > Without looking too deeply, the patch seems sensible to me. However,
> > > > I'm CC'ing Alexander and Paul :-)
> > >
> > > Thank you for pointing this out. And thanks to Neil for the fix.
> > >
> > > Looks good at the first glance. I'm going to review this in the next
> > > couple of days.
> >
> > I've reviewed enforce_generic_type_consistency() more carefully. It
> > looks for me that this function requires more significant rework. For
> > instance, these two functions throw errors, but it seems that both of
> > them should work.
> >
> > create function multirange_func(r anycompatiblerange)
> > returns anycompatiblemultirange as 'select multirange($1);' language sql;
> > create function range_func(r anycompatiblemultirange)
> > returns anycompatiblerange as 'select multirange($1);' language sql;
> >
> > # select multirange_func(int4range(1,10));
> > ERROR: could not identify anycompatiblemultirange type
> >
> > # select range_func(int4multirange(int4range(1,10)));
> > ERROR: could not determine polymorphic type anycompatiblerange
> > because input has type unknown
> >
> > So, I'm still investigating this.
>
> The second function was intended to be this to be a meaningful
> example. But anyway it fails with the same error.
>
> create function range_func(r anycompatiblemultirange)
> returns anycompatiblerange as 'select range_merge($1);' language sql;

I've a bit stuck in understanding of
enforce_generic_type_consistency(). There is a set of "argument
declared..." errors. But they aren't present in regression tests.
And I didn't manage to reproduce them, because a function is filtered
out before entering enforce_generic_type_consistency() and I get just
"No function matches ..." error.

Are "argument declared..." errors just internal, which users shouldn't
normally see. Or do they happen in some circumstances? If latter,
then I think it should be added to the regression tests.

I really appreciate a hint here.

------
Regards,
Alexander Korotkov