From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-hackers@lists.postgresql.org
cc: Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>,
        Thomas Munro <thomas.munro@gmail.com>
Subject: Re: Pointer subtraction with a null pointer
In-reply-to: <48826.1648310694@sss.pgh.pa.us>
References: <48826.1648310694@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Sat, 26 Mar 2022 12:04:54 -0400"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <49359.1648311192.1@sss.pgh.pa.us>
Content-Transfer-Encoding: quoted-printable
Date: Sat, 26 Mar 2022 12:13:12 -0400
Message-ID: <49360.1648311192@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/49360.1648311192%40sss.pgh.pa.us>
Precedence: bulk

I wrote:
> Several of Andres' buildfarm animals have recently started to whine
> that "performing pointer subtraction with a null pointer has undefined
> behavior" for assorted places in freepage.c.

Ah, sorry, I meant to include a link:

https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=3Dmylodon&dt=
=3D2022-03-26%2000%3A02%3A10&stg=3Dmake

This code is old, but mylodon wasn't doing that a week ago, so
Andres must've updated the compiler and/or changed its options.
kestrel and olingo are reporting it too, but they're new.

			regards, tom lane