Re: BUG #18722: Processing arrays with plpgsql raises errors

On Mon, 25 Nov 2024 at 19:16, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Dean Rasheed <dean.a.rasheed@gmail.com> writes:
> > I didn't mean do it in all cases, I just meant the NullIfExpr case
> > identified here. My point was that instead of modifying the evaluation
> > code for EEOP_NULLIF to make it call
> > MakeExpandedObjectReadOnlyInternal(), it would be easier to insert a
> > EEOP_MAKE_READONLY step for the first argument of the EEOP_NULLIF
> > step.
>
> But then the NULLIF step would only have access to the R/O pointer,
> no?  We do want to pass on a R/W pointer to the output, if we got
> one, to handle cases like
>         fconsumer(NULLIF(fproducer(...), ...), ...)
> Admittedly that's a pretty edgy edge-case, but still we're leaving
> money on the table if we don't do it.  So I think we have to deal
> with the issue within NULLIF.
>

OK, that makes sense.

Regards,
Dean