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From: Kees Cook <keescook@chromium.org>
To: Qing Zhao <qing.zhao@oracle.com>
Cc: Joseph Myers <joseph@codesourcery.com>,
	Richard Biener <rguenther@suse.de>,
	jakub Jelinek <jakub@redhat.com>,
	gcc Patches <gcc-patches@gcc.gnu.org>,
	Nathan Sidwell <Nathan@acm.org>, martin Sebor <msebor@gmail.com>
Subject: Re: [[GCC13][Patch][V3] 1/2] Add a new option -fstrict-flex-array[=n] and new attribute strict_flex_array
Date: Wed, 31 Aug 2022 15:17:01 -0700	[thread overview]
Message-ID: <202208311505.5B794D17C@keescook> (raw)
In-Reply-To: <792FF180-4337-41BD-81BE-D695CD2623CE@oracle.com>

On Wed, Aug 31, 2022 at 08:16:49PM +0000, Qing Zhao wrote:
> 
> > On Aug 31, 2022, at 4:09 PM, Joseph Myers <joseph@codesourcery.com> wrote:
> > 
> > On Wed, 31 Aug 2022, Qing Zhao wrote:
> > 
> >>>> When -std=gnu89 + -fstrict-flex-array=3 (ONLY C99 flexible array member 
> >>>> [] is treated as a valid flexible array) present together,
> >>> 
> >>> That seems reasonable enough without a warning.  If people want a warning 
> >>> for flexible array members in older language modes, they can use 
> >>> -pedantic; I don't think we need to warn for any particular 
> >>> -fstrict-flex-array modes there.
> >> 
> >> So, you mean,
> >> 
> >> 1. GCC with -std=gnu89 support all [0], [1], and [] as Flexible array member;
> >> 2. Therefore. -std=gnu89 + -fstrict-flex-array=3 does not need a warning;
> >> 
> >> ?
> > 
> > Yes.
> > 
> >> Then, how about:
> >> 
> >> -std=c89:
> >> 
> >> 1. GCC with -std=c89 also support all [0], [1], and [] as Flexible array member;
> >> 2, therefore, -std=c89 + -fstrict-flex-array does not need a warning too.
> >> 
> >> ?
> > 
> > Yes.
> > 
> 
> Okay, I am fine with this.
> 
> Richard and Kees,  what’s your opinion on this?

Agreed: I think it's fine not to warn about these "conflicting" flags in
those cases. It looks like the C standard warnings about flexible arrays
are already hidden behind -Wpedantic, so nothing else is needed, IMO.
Using -fstrict-flex-arrays just enforces that warning. ;)

-- 
Kees Cook

      parent reply	other threads:[~2022-08-31 22:17 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-17 14:40 Qing Zhao
2022-08-17 14:40 ` [[GCC13][Patch][V3] 2/2] Use array_at_struct_end_p in __builtin_object_size [PR101836] Qing Zhao
2022-08-26  8:49   ` Richard Biener
2022-08-26 13:37     ` Qing Zhao
2022-08-26  8:48 ` [[GCC13][Patch][V3] 1/2] Add a new option -fstrict-flex-array[=n] and new attribute strict_flex_array Richard Biener
2022-08-26 13:47   ` Qing Zhao
2022-08-29  8:04     ` Richard Biener
2022-08-30 20:30 ` Fwd: " Qing Zhao
2022-08-30 20:30   ` Qing Zhao
2022-08-30 22:53   ` Joseph Myers
2022-08-31 14:00     ` Qing Zhao
2022-08-31 17:21       ` Joseph Myers
2022-08-31 17:21         ` Joseph Myers
2022-08-31 18:55         ` Qing Zhao
2022-08-31 19:24           ` Qing Zhao
2022-08-31 19:29           ` Joseph Myers
2022-08-31 19:29             ` Joseph Myers
2022-08-31 19:47             ` Qing Zhao
2022-08-31 19:52               ` Joseph Myers
2022-08-31 20:06                 ` Qing Zhao
2022-08-31 20:09                   ` Joseph Myers
2022-08-31 20:16                     ` Qing Zhao
2022-08-31 20:35                       ` Qing Zhao
2022-08-31 22:23                         ` Kees Cook
2022-09-01  6:11                           ` Richard Biener
2022-09-04 14:17                             ` Qing Zhao
2022-08-31 22:17                       ` Kees Cook [this message]

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