From: Tom Lane <tgl@sss.pgh.pa.us>
To: Dean Rasheed <dean.a.rasheed@gmail.com>
cc: exclusion@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18722: Processing arrays with plpgsql raises errors
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Comments: In-reply-to Dean Rasheed <dean.a.rasheed@gmail.com>
	message dated "Mon, 25 Nov 2024 17:59:05 +0000"
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Date: Mon, 25 Nov 2024 14:16:11 -0500
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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.

			regards, tom lane