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From: Arnd Bergmann <arnd@kernel.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: David Laight <David.Laight@aculab.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	"David S . Miller" <davem@davemloft.net>,
	"sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sparc: mdesc: Fix compile error seen with gcc 11.x
Date: Tue, 14 Sep 2021 16:53:35 +0200	[thread overview]
Message-ID: <CAK8P3a1mrZHHfN0dK6nV3jpBmnYm+jG=M8j2u=1=ZPkLuf2DXQ@mail.gmail.com> (raw)
In-Reply-To: <3b069cde-6f15-1df1-fbed-e8d94d0ef173@roeck-us.net>

On Tue, Sep 14, 2021 at 4:24 PM Guenter Roeck <linux@roeck-us.net> wrote:
> On 9/14/21 7:17 AM, David Laight wrote:
> >> Sorry, I didn't realize that a field of size 0 increases the structure size
> >> on sparc. I had checked the size of the old and the new structure with gcc
> >> on x86_64 and didn't see a field size increase.
> >
> > clang output doesn't change:
> >
> > https://godbolt.org/z/bTeeq19j1
> >
> > gcc ought to generate the same size.
> >
> > It ought to be 'char data[];' though.
> >
>
> I am never sure if [] or [0] is "correct". Anyway, is there agreement that this
> is an acceptable solution ? I'll be happy to resend if that is the case.

Yes, looks good to me, in the [] version. I think the [0] version can be
interpreted as a zero-length array that may not be accessed, while the
[] flexible array syntax clearly means that extra data follows, and it's
part of the C standard now, while [0] is a gcc extension.

        Arnd

  reply	other threads:[~2021-09-14 14:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-13 16:37 [PATCH] sparc: mdesc: Fix compile error seen with gcc 11.x Guenter Roeck
     [not found] ` <YT+SPIAl0IdWOAn/@ravnborg.org>
2021-09-13 18:52   ` Guenter Roeck
2021-09-14 12:02     ` Anatoly Pugachev
2021-09-14 14:17     ` David Laight
2021-09-14 14:24       ` Guenter Roeck
2021-09-14 14:53         ` Arnd Bergmann [this message]
2021-09-14 15:03           ` David Laight
2021-09-14 15:17             ` Guenter Roeck

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