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Date: Wed, 31 Aug 2022 19:52:27 +0000
From: Joseph Myers <joseph@codesourcery.com>
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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
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On Wed, 31 Aug 2022, Qing Zhao wrote:

> Does the above mean that -std=gnu89 does not support C99 flexible array 
> member, then

No.

Flexible array members are supported by GCC in all C standards modes.  The 
C90 standard doesn't support them, but that's irrelevant to what GCC 
supports; it just means a diagnostic is required for strict conformance in 
pre-C99 modes.

> 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.

-- 
Joseph S. Myers
joseph@codesourcery.com