From: Richard Biener <rguenther@suse.de>
To: Siddhesh Poyarekar <siddhesh@gotplt.org>
Cc: Kees Cook <keescook@chromium.org>,
Qing Zhao <qing.zhao@oracle.com>,
joseph@codesourcery.com, gcc-patches@gcc.gnu.org,
siddhesh@gcc.gnu.org
Subject: Re: [V2][PATCH 1/1] Add a new warning option -Wstrict-flex-arrays.
Date: Fri, 2 Dec 2022 07:16:31 +0000 (UTC) [thread overview]
Message-ID: <nycvar.YFH.7.77.849.2212020712430.17722@jbgna.fhfr.qr> (raw)
In-Reply-To: <898dfeed-f392-fb86-7fbd-f99d335c7a64@gotplt.org>
On Thu, 1 Dec 2022, Siddhesh Poyarekar wrote:
> On 2022-12-01 11:42, Kees Cook wrote:
> > On Wed, Nov 30, 2022 at 02:25:56PM +0000, Qing Zhao wrote:
> >> '-Wstrict-flex-arrays'
> >> Warn about inproper usages of flexible array members according to
> >> the LEVEL of the 'strict_flex_array (LEVEL)' attribute attached to
> >> the trailing array field of a structure if it's available,
> >> otherwise according to the LEVEL of the option
> >> '-fstrict-flex-arrays=LEVEL'.
> >>
> >> This option is effective only when LEVEL is bigger than 0.
> >> Otherwise, it will be ignored with a warning.
> >>
> >> when LEVEL=1, warnings will be issued for a trailing array
> >> reference of a structure that have 2 or more elements if the
> >> trailing array is referenced as a flexible array member.
> >>
> >> when LEVEL=2, in addition to LEVEL=1, additional warnings will be
> >> issued for a trailing one-element array reference of a structure if
> >> the array is referenced as a flexible array member.
> >>
> >> when LEVEL=3, in addition to LEVEL=2, additional warnings will be
> >> issued for a trailing zero-length array reference of a structure if
> >> the array is referenced as a flexible array member.
> >>
> >> At the same time, -Warray-bounds is updated:
> >
> > Why is there both -Wstrict-flex-arrays and -Warray-bounds? I thought
> > only the latter was going to exist?
Sorry for appearantly not being clear - I was requesting
-Wstrict-flex-arrays to be dropped and instead adjusting -Warray-bounds
to adhere to -fstrict-flex-arrays in both =1 and =2 where then =2
would only add the intermediate pointer results verification.
I think that's reasonable if documented since the default behavior
with -Wall will not change then unless the -fstrict-flex-arrays
default is altered.
> Oh my understanding of the consensus was to move flex array related diagnosis
> from -Warray-bounds to -Wstring-flex-arrays as Qing has done. If only the
> former exists then instead of removing the flex array related statement in the
> documentation as Richard suggested, we need to enhance it to say that
> behaviour of -Warray-bounds will depend on -fstrict-flex-arrays.
>
> -Warray-bounds does diagnosis beyond just flexible arrays, in case that's the
> confusion.
Richard.
--
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)
next prev parent reply other threads:[~2022-12-02 7:16 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-30 14:25 [V2][PATCH 0/1]Add " Qing Zhao
2022-11-30 14:25 ` [V2][PATCH 1/1] Add " Qing Zhao
2022-12-01 16:42 ` Kees Cook
2022-12-01 17:04 ` Qing Zhao
2022-12-01 17:18 ` Kees Cook
2022-12-01 17:48 ` Qing Zhao
2022-12-01 19:45 ` Siddhesh Poyarekar
2022-12-01 22:27 ` Qing Zhao
2022-12-01 23:19 ` Kees Cook
2022-12-01 23:53 ` Siddhesh Poyarekar
2022-12-02 7:16 ` Richard Biener [this message]
2022-12-02 7:20 ` Richard Biener
2022-12-02 14:43 ` Qing Zhao
2022-12-05 15:16 ` Richard Biener
2022-12-05 15:20 ` Qing Zhao
2022-12-02 14:40 ` Qing Zhao
2022-12-06 16:14 [V3][PATCH 0/2]Update -Warray-bounds with -fstrict-flex-arrays Qing Zhao
2022-12-06 16:14 ` [V2][PATCH 1/1] Add a new warning option -Wstrict-flex-arrays Qing Zhao
2022-12-06 16:16 ` Qing Zhao
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