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Date: Fri, 08 Mar 2024 10:05:27 -0600
Message-Id: <CZOHWDYQJQCQ.23A5RRV1E05N2@neon.tech>
To: "Michael Paquier" <michael@paquier.xyz>
From: "Tristan Partin" <tristan@neon.tech>
Cc: "Sutou Kouhei" <kou@clear-code.com>, <pgsql-hackers@postgresql.org>
Subject: Re: meson: Specify -Wformat as a common warning flag for extensions
References: <20240122.141139.931086145628347157.kou@clear-code.com>
 <CZO4L8L0KP7K.1RWJWEAGL8UMN@neon.tech> <Zeqw9vGrYlb250aO@paquier.xyz>
In-Reply-To: <Zeqw9vGrYlb250aO@paquier.xyz>
Archived-At: <https://www.postgresql.org/message-id/CZOHWDYQJQCQ.23A5RRV1E05N2%40neon.tech>
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On Fri Mar 8, 2024 at 12:32 AM CST, Michael Paquier wrote:
> On Thu, Mar 07, 2024 at 11:39:39PM -0600, Tristan Partin wrote:
> > It sounds like a legitimate issue. I have confirmed the issue exists wi=
th a
> > pg_config compiled with Meson. I can also confirm that this issue exist=
s in
> > the autotools build.
>
> First time I'm hearing about that, but I'll admit that I am cheating
> because -Wformat is forced in my local builds for some time now.  I'm
> failing to see the issue with meson and ./configure even if I remove
> the switch, though, using a recent version of gcc at 13.2.0, but
> perhaps Debian does something underground.  Are there version and/or
> environment requirements to be aware of?
>
> Forcing -Wformat implies more stuff that can be disabled with
> -Wno-format-contains-nul, -Wno-format-extra-args, and
> -Wno-format-zero-length, but the thing is that we're usually very
> conservative with such additions in the scripts.  See also
> 8b6f5f25102f, done, I guess, as an answer to this thread:
> https://www.postgresql.org/message-id/4D431505.9010002%40dunslane.net
>
> A quick look at the past history of pgsql-hackers does not mention
> that as a problem, either, but I may have missed something.

Ok, I figured this out. -Wall implies -Wformat=3D1. We set warning_level=20
to 1 in the Meson project() call, which implies -Wall, and set -Wall in=20
CFLAGS for autoconf. That's the reason we don't get issues building=20
Postgres. A user making use of the pg_config --cflags option, as Sutou=20
is, *will* run into the aforementioned issues, since we don't propogate=20
-Wall into pg_config.

	$ gcc $(pg_config --cflags) -E - < /dev/null > /dev/null
	cc1: warning: =E2=80=98-Wformat-security=E2=80=99 ignored without =E2=80=
=98-Wformat=E2=80=99 [-Wformat-security]
	$ gcc -Wall $(pg_config --cflags) -E - < /dev/null > /dev/null
	(nothing printed)

--=20
Tristan Partin
Neon (https://neon.tech)