From: Kevin Easton <kevin@guarana.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Joe Perches <joe@perches.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Karsten Keil <isdn@linux-pingi.de>,
"David S. Miller" <davem@davemloft.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, Guenter Roeck <linux@roeck-us.net>,
IDE-ML <linux-ide@vger.kernel.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Networking <netdev@vger.kernel.org>
Subject: Re: [PATCH 05/14] isdn: isdnloop: suppress a gcc-7 warning
Date: Sat, 15 Jul 2017 00:20:23 -0400 [thread overview]
Message-ID: <20170715042022.GA18345@la.guarana.org> (raw)
In-Reply-To: <CAK8P3a2fYr11L-0sg-veKx5F5dGH5btQAhSZtFbNXxVtcHd8dg@mail.gmail.com>
On Fri, Jul 14, 2017 at 12:37:05PM +0200, Arnd Bergmann wrote:
> On Fri, Jul 14, 2017 at 12:08 PM, Joe Perches <joe@perches.com> wrote:
> > On Fri, 2017-07-14 at 11:25 +0200, Arnd Bergmann wrote:
> >> We test whether a bit is set in a mask here, which is correct
> >> but gcc warns about it as it thinks it might be confusing:
> >>
> >> drivers/isdn/isdnloop/isdnloop.c:412:37: error: ?: using integer constants in boolean context, the expression will always evaluate to 'true' [-Werror=int-in-bool-context]
...
> > Perhaps this is a logic defect and should be:
> >
> > if (!(card->flags & ((channel) ? ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE)))
>
> Yes, good catch. I had thought about it for a bit whether that would be
> the answer, but come to the wrong conclusion on my own.
>
> Note that the version you suggested will still have the warning, so I think
> it needs to be
It shouldn't - the warning is for using an integer *constant* in boolean
context, but the result of & isn't a constant and should be fine.
!(flags & mask) is a very common idiom.
- Kevin
next prev parent reply other threads:[~2017-07-15 4:20 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-14 9:25 [PATCH 00/14] gcc-7 warnings Arnd Bergmann
2017-07-14 9:25 ` [PATCH, RESEND 01/14] ide: avoid warning for timings calculation Arnd Bergmann
2017-07-14 9:25 ` [PATCH, RESEND 02/14] ata: avoid gcc-7 warning in ata_timing_quantize Arnd Bergmann
2017-07-15 10:56 ` Tejun Heo
2017-07-14 9:25 ` [PATCH, RESEND 03/14] drm/vmwgfx: avoid gcc-7 parentheses warning Arnd Bergmann
2017-07-14 10:11 ` Jani Nikula
2017-07-14 19:21 ` Linus Torvalds
2017-07-14 19:23 ` Linus Torvalds
2017-07-14 20:28 ` Arnd Bergmann
2017-07-17 13:15 ` Sinclair Yeh
2017-07-14 9:25 ` [PATCH 04/14] x86: math-emu: avoid -Wint-in-bool-context warning Arnd Bergmann
2017-07-14 9:25 ` [PATCH 05/14] isdn: isdnloop: suppress a gcc-7 warning Arnd Bergmann
2017-07-14 10:08 ` Joe Perches
2017-07-14 10:37 ` Arnd Bergmann
2017-07-15 4:20 ` Kevin Easton [this message]
2017-07-14 9:25 ` [PATCH 06/14] acpi: thermal: fix gcc-6/ccache warning Arnd Bergmann
2017-07-14 9:25 ` [PATCH 07/14] proc/kcore: hide a harmless warning Arnd Bergmann
2017-07-14 12:28 ` Ard Biesheuvel
2017-07-18 19:53 ` Arnd Bergmann
2017-07-18 19:55 ` Ard Biesheuvel
2017-07-18 20:01 ` Arnd Bergmann
2017-07-18 20:07 ` Ard Biesheuvel
2017-07-18 20:21 ` Arnd Bergmann
2017-07-14 9:25 ` [PATCH 08/14] Input: adxl34x - fix gcc-7 -Wint-in-bool-context warning Arnd Bergmann
2017-07-14 19:24 ` Linus Torvalds
2017-07-14 20:17 ` Arnd Bergmann
2017-07-14 21:40 ` Dmitry Torokhov
2017-07-14 9:30 ` [PATCH 09/14] SFI: fix tautological-compare warning Arnd Bergmann
2017-07-14 9:31 ` [PATCH 10/14] staging:iio:resolver:ad2s1210 fix negative IIO_ANGL_VEL read Arnd Bergmann
2017-07-15 11:42 ` Jonathan Cameron
2017-07-14 9:31 ` [PATCH 11/14] IB/uverbs: fix gcc-7 type warning Arnd Bergmann
2017-07-14 9:46 ` Leon Romanovsky
2017-07-14 9:31 ` [PATCH 12/14] drm/nouveau/clk: fix gcc-7 -Wint-in-bool-context warning Arnd Bergmann
2017-07-14 9:31 ` [PATCH 13/14] iopoll: avoid " Arnd Bergmann
2017-07-14 9:55 ` Joe Perches
2017-07-14 10:22 ` Arnd Bergmann
2017-07-14 9:36 ` [PATCH 14/14] [media] fix warning on v4l2_subdev_call() result interpreted as bool Arnd Bergmann
2017-07-14 12:05 ` Dan Carpenter
2017-07-14 12:27 ` Arnd Bergmann
2017-07-14 12:55 ` Dan Carpenter
2017-07-14 13:09 ` Dan Carpenter
2017-07-14 19:32 ` Arnd Bergmann
2017-07-14 12:41 ` Dan Carpenter
2017-07-17 13:45 ` Hans Verkuil
2017-07-17 14:26 ` Arnd Bergmann
2017-07-17 14:28 ` Dan Carpenter
2017-07-17 14:32 ` Hans Verkuil
2017-07-17 14:35 ` Hans Verkuil
2017-07-17 21:23 ` Arnd Bergmann
2017-07-14 10:29 ` [PATCH 00/14] gcc-7 warnings Greg Kroah-Hartman
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