From: Tom Lane <tgl@sss.pgh.pa.us>
To: Thomas Munro <thomas.munro@gmail.com>
cc: James Hilliard <james.hilliard1@gmail.com>,
        David Steele <david@pgmasters.net>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
        Sergey Shinderuk <s.shinderuk@postgrespro.ru>
Subject: Re: [PATCH v3 1/1] Fix detection of preadv/pwritev support for OSX.
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Comments: In-reply-to Thomas Munro <thomas.munro@gmail.com>
	message dated "Tue, 30 Mar 2021 12:54:11 +1300"
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Date: Tue, 30 Mar 2021 01:58:37 -0400
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Thomas Munro <thomas.munro@gmail.com> writes:
> I'll move it when committing.  I'll let this patch sit for another day
> to see if any other objections show up.

FWIW, I remain fairly strongly against this, precisely because of the
point that it requires us to start using a randomly different
feature-probing technology anytime Apple decides that they're going to
implement some standard API that they didn't before.  Even if it works
everywhere for preadv/pwritev (which we won't know in advance of
buildfarm testing, and maybe not then, since detection failures will
probably be silent), it seems likely that we'll hit some case in the
future where this interacts badly with some other platform's weirdness.
We haven't claimed in the past to support MACOSX_DEPLOYMENT_TARGET,
and I'm not sure we should start now.  How many people actually care
about that?

			regards, tom lane