Date: Fri, 13 Mar 2026 09:18:59 +0000
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>,
	Peter Eisentraut <peter@eisentraut.org>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: Defend against -ffast-math in meson builds
Message-ID: <abPWg4DJx6GciBDB@ip-10-97-1-34.eu-west-3.compute.internal>
References: <abFXfKC8zR0Oclon@ip-10-97-1-34.eu-west-3.compute.internal>
 <vwnxbsap65km373ghtqhhvhwnc35suwraegb7z5op4okxyuwzu@kpaumampogpe>
 <a9d82d5f-58c5-4252-960f-f91cb5bc5a99@eisentraut.org>
 <3316.1773242385@sss.pgh.pa.us>
 <abGPko4lPv/Bj6Bt@ip-10-97-1-34.eu-west-3.compute.internal>
 <3583.1773247555@sss.pgh.pa.us>
 <dx5yldtsqih2htsd7cz3tfxt5zhuggpeegwllz7wz2r26tll5h@cwhsw4ddfbc5>
 <abKU4cLSlRu6v3J+@ip-10-97-1-34.eu-west-3.compute.internal>
 <4425.1773328251@sss.pgh.pa.us>
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="LlTAxJ2fZwYEH6fs"
Content-Disposition: inline
In-Reply-To: <4425.1773328251@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/abPWg4DJx6GciBDB%40ip-10-97-1-34.eu-west-3.compute.internal>
Precedence: bulk


--LlTAxJ2fZwYEH6fs
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

Hi,

On Thu, Mar 12, 2026 at 11:10:51AM -0400, Tom Lane wrote:
> Bertrand Drouvot <bertranddrouvot.pg@gmail.com> writes:
> > On Wed, Mar 11, 2026 at 01:48:31PM -0400, Andres Freund wrote:
> >> On 2026-03-11 12:45:55 -0400, Tom Lane wrote:
> >>> So no, I don't wanna support this.  But maybe we should move the
> >>> code-level tests out of the datetime files and into utils/float.h
> >>> or some such place.
> 
> >> I think it's probably better to have it in a .c file (maybe float.c), I could
> >> kinda imagine some extension intentionally enabling -ffast-math, because it
> >> does something numerically intensive where the incorrectness doesn't matter.
> 
> > I think that you have a good point about the extension. That said a .h file
> > could also prevent the extension to make use of -ffast-math "accidentally".
> 
> Yeah, that was my thought too.  But I think Andres has a point that in
> principle an extension could use -ffast-math intentionally, so I'm
> content to just put the test in float.c.

Yeah, I do agree. Something like in the attached?

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

--LlTAxJ2fZwYEH6fs
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v2-0001-Move-ffast-math-defense-to-float.c-and-remove-the.patch"