From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] user-defined numeric data types triggering ERROR:
 unsupported type
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Comments: In-reply-to Tomas Vondra <tomas.vondra@2ndquadrant.com>
	message dated "Sun, 04 Mar 2018 03:14:50 +0100"
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Date: Sun, 04 Mar 2018 11:59:42 -0500
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Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
> On 03/04/2018 02:37 AM, Tom Lane wrote:
>> I was kind of underwhelmed with these test cases, too, so I didn't
>> commit them.  But they were good for proving that the bytea bug
>> wasn't hypothetical :-)

> Underwhelmed in what sense? Should the tests be constructed in some
> other way, or do you think it's something that doesn't need the tests?

The tests seemed pretty ugly, and I don't think they were doing much to
improve test coverage by adding all those bogus operators.  Now, a look at
https://coverage.postgresql.org/src/backend/utils/adt/selfuncs.c.gcov.html
says that our test coverage for convert_to_scalar stinks, but we could
(and probably should) improve that just by testing extant operators.

A concrete argument for not creating those operators is that they pose a
risk of breaking concurrently-running tests by capturing inexact argument
matches (cf CVE-2018-1058).  There are ways to get around that, eg run
the whole test inside a transaction we never commit; but I don't really
think we need the complication.

			regards, tom lane