Mime-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=UTF-8; format=Flowed
Date: Wed, 19 Jul 2023 12:15:31 -0500
Message-Id: <CU6BH3JA3GCY.25ETDNK3LVULF@gonk>
To: "Peter Eisentraut" <peter@eisentraut.org>,
 <pgsql-hackers@postgresql.org>
From: "Tristan Partin" <tristan@neon.tech>
Subject: Re: Fix last unitialized memory warning
References: <CT6HJ3U8068R.3A8SJMV02D9BC@gonk>
 <8f7880cc-3622-1c0a-a126-5b47aafeee51@eisentraut.org>
 <CTUJMJ1B57SL.3T8TKNTE9XSVD@gonk>
 <fe3d9d88-9702-3339-d86a-98a121244c9c@eisentraut.org>
 <CTV4SEUNM92R.2OM4SN8LB7CQN@gonk>
 <54989bdd-d6fe-92dc-a7e3-f4f31252b7eb@eisentraut.org>
In-Reply-To: <54989bdd-d6fe-92dc-a7e3-f4f31252b7eb@eisentraut.org>
Archived-At: 
 <https://www.postgresql.org/message-id/CU6BH3JA3GCY.25ETDNK3LVULF%40gonk>
Precedence: bulk

On Sun Jul 9, 2023 at 2:23 AM CDT, Peter Eisentraut wrote:
> On 06.07.23 15:41, Tristan Partin wrote:
> > On Thu Jul 6, 2023 at 3:21 AM CDT, Peter Eisentraut wrote:
> >> On 05.07.23 23:06, Tristan Partin wrote:
> >>> Thanks for following up. My system is Fedora 38. I can confirm this i=
s
> >>> still happening on master.
> >>>
> >>> $ gcc --version
> >>> gcc (GCC) 13.1.1 20230614 (Red Hat 13.1.1-4)
> >>> Copyright (C) 2023 Free Software Foundation, Inc.
> >>> This is free software; see the source for copying conditions.  There =
is NO
> >>> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PU=
RPOSE.
> >>> $ meson setup build --buildtype=3Drelease
> >>
> >> This buildtype turns on -O3 warnings.  We have usually opted against
> >> chasing warnings in -O3 level because there are often some
> >> false-positive uninitialized variable warnings with every new compiler=
.
> >>
> >> Note that we have set the default build type to debugoptimized, for th=
at
> >> reason.
> >=20
> > Good to know, thanks.
> >=20
> > Regarding the original patch, do you think it is good to be applied?
>
> That patch looks reasonable.  But I can't actually reproduce the=20
> warning, even with gcc-13.  I do get the warning from plpgsql.  Can you=
=20
> show the warning you are seeing?

Here is the full warning that the original patch suppresses.

[1360/1876] Compiling C object src/bin/pgbench/pgbench.p/pgbench.c.o
In function =E2=80=98coerceToInt=E2=80=99,
    inlined from =E2=80=98evalStandardFunc=E2=80=99 at ../src/bin/pgbench/p=
gbench.c:2607:11:
../src/bin/pgbench/pgbench.c:2032:17: warning: =E2=80=98vargs[0].type=E2=80=
=99 may be used uninitialized [-Wmaybe-uninitialized]
 2032 |         if (pval->type =3D=3D PGBT_INT)
      |             ~~~~^~~~~~
../src/bin/pgbench/pgbench.c: In function =E2=80=98evalStandardFunc=E2=80=
=99:
../src/bin/pgbench/pgbench.c:2240:22: note: =E2=80=98vargs=E2=80=99 declare=
d here
 2240 |         PgBenchValue vargs[MAX_FARGS];
      |                      ^~~~~
In function =E2=80=98coerceToInt=E2=80=99,
    inlined from =E2=80=98evalStandardFunc=E2=80=99 at ../src/bin/pgbench/p=
gbench.c:2607:11:
../src/bin/pgbench/pgbench.c:2034:32: warning: =E2=80=98vargs[0].u.ival=E2=
=80=99 may be used uninitialized [-Wmaybe-uninitialized]
 2034 |                 *ival =3D pval->u.ival;
      |                         ~~~~~~~^~~~~
../src/bin/pgbench/pgbench.c: In function =E2=80=98evalStandardFunc=E2=80=
=99:
../src/bin/pgbench/pgbench.c:2240:22: note: =E2=80=98vargs=E2=80=99 declare=
d here
 2240 |         PgBenchValue vargs[MAX_FARGS];
      |                      ^~~~~
In function =E2=80=98coerceToInt=E2=80=99,
    inlined from =E2=80=98evalStandardFunc=E2=80=99 at ../src/bin/pgbench/p=
gbench.c:2607:11:
../src/bin/pgbench/pgbench.c:2039:40: warning: =E2=80=98vargs[0].u.dval=E2=
=80=99 may be used uninitialized [-Wmaybe-uninitialized]
 2039 |                 double          dval =3D rint(pval->u.dval);
      |                                        ^~~~~~~~~~~~~~~~~~
../src/bin/pgbench/pgbench.c: In function =E2=80=98evalStandardFunc=E2=80=
=99:
../src/bin/pgbench/pgbench.c:2240:22: note: =E2=80=98vargs=E2=80=99 declare=
d here
 2240 |         PgBenchValue vargs[MAX_FARGS];
      |                      ^~~~~

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