From: Joseph Myers <joseph@codesourcery.com>
To: Qing Zhao <qing.zhao@oracle.com>
Cc: jakub Jelinek <jakub@redhat.com>,
richard Biener <rguenther@suse.de>,
Kees Cook <keescook@chromium.org>,
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 19:29:13 +0000 [thread overview]
Message-ID: <alpine.DEB.2.22.394.2208311927220.498823@digraph.polyomino.org.uk> (raw)
In-Reply-To: <B92A4442-0B40-4C62-A725-FCC8176A00F3@oracle.com>
[-- Attachment #1: Type: text/plain, Size: 888 bytes --]
On Wed, 31 Aug 2022, Qing Zhao via Gcc-patches wrote:
> > How is level 3 (thus -fstrict-flex-array) interpreted when you specify
> > -std=c89? How for -std=gnu89?
>
> 1. what’s the major difference between -std=c89 and -std=gnu89 on flexible array? (Checked online, cannot find a concrete answer on this).
> ** my understanding is: -std=c89 will not support any flexible array (neither [], [0], [1]), but -std=gnu89 will support [0] and [1], but not [].
> Is this correct?
Flexible array members are supported in all C standard modes, since they
don't affect the semantics of any valid pre-C99 program (only make valid
programs that were previously erroneous).
With -std=c89 or -std=gnu89, -pedantic will give a warning "ISO C90 does
not support flexible array members" and -pedantic-errors will change that
to an error.
--
Joseph S. Myers
joseph@codesourcery.com
WARNING: multiple messages have this Message-ID
From: Joseph Myers <joseph@codesourcery.com>
To: Qing Zhao <qing.zhao@oracle.com>
Cc: jakub Jelinek <jakub@redhat.com>,
richard Biener <rguenther@suse.de>,
Kees Cook <keescook@chromium.org>,
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 19:29:13 +0000 [thread overview]
Message-ID: <alpine.DEB.2.22.394.2208311927220.498823@digraph.polyomino.org.uk> (raw)
Message-ID: <20220831192913.GTf-fo9naRlxVYkvI-WbJZsfG3LoyOQC_FmAVBzM6bI@z> (raw)
In-Reply-To: <B92A4442-0B40-4C62-A725-FCC8176A00F3@oracle.com>
On Wed, 31 Aug 2022, Qing Zhao via Gcc-patches wrote:
> > How is level 3 (thus -fstrict-flex-array) interpreted when you specify
> > -std=c89? How for -std=gnu89?
>
> 1. what’s the major difference between -std=c89 and -std=gnu89 on flexible array? (Checked online, cannot find a concrete answer on this).
> ** my understanding is: -std=c89 will not support any flexible array (neither [], [0], [1]), but -std=gnu89 will support [0] and [1], but not [].
> Is this correct?
Flexible array members are supported in all C standard modes, since they
don't affect the semantics of any valid pre-C99 program (only make valid
programs that were previously erroneous).
With -std=c89 or -std=gnu89, -pedantic will give a warning "ISO C90 does
not support flexible array members" and -pedantic-errors will change that
to an error.
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2022-08-31 19:29 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 [this message]
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
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