From: Julien Grall <julien.grall@arm.com>
To: Jan Beulich <JBeulich@suse.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH v2] dom0-build: fix build with clang5
Date: Mon, 29 Jul 2019 11:05:45 +0100 [thread overview]
Message-ID: <20318831-02d8-cce3-46e9-b4eb22506dce@arm.com> (raw)
In-Reply-To: <5c88239b-de0f-5f81-72c4-7fdb07524278@suse.com>
Hi,
On 7/17/19 7:47 AM, Jan Beulich wrote:
> With non-empty CONFIG_DOM0_MEM clang5 produces
>
> dom0_build.c:344:24: error: use of logical '&&' with constant operand [-Werror,-Wconstant-logical-operand]
> if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] )
> ^ ~~~~~~~~~~~~~~~~~~
> dom0_build.c:344:24: note: use '&' for a bitwise operation
> if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] )
> ^~
> &
> dom0_build.c:344:24: note: remove constant to silence this warning
> if ( !dom0_mem_set && CONFIG_DOM0_MEM[0] )
> ~^~~~~~~~~~~~~~~~~~~~~
> 1 error generated.
>
> Obviously neither of the two suggestions are an option here. Oddly
> enough swapping the operands of the && helps, while e.g. casting or
> parenthesizing doesn't. Another workable variant looks to be the use of
> !! on the constant.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> v2: Also adjust the Arm incarnation of the same construct.
> ---
> I'm open to going the !! or yet some different route (but not really the
> suggested strlen() one). No matter which one we choose, I'm afraid it is
> going to remain guesswork what newer (and future) versions of clang will
> choke on.
I quite like the strlen one, however looking around online this may not
solve the problem. AFAIK, Clang is not happy because the constant is not
a boolean.
So !! or != 0 should work here.
Cheers,
--
Julien Grall
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next prev parent reply other threads:[~2019-07-29 10:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 6:47 [Xen-devel] [PATCH v2] dom0-build: fix build with clang5 Jan Beulich
2019-07-29 10:05 ` Julien Grall [this message]
2019-07-29 11:36 ` Jan Beulich
2019-12-20 16:26 ` [Xen-devel] Ping: " Jan Beulich
2020-01-11 16:27 ` Julien Grall
2020-01-15 9:56 ` Roger Pau Monné
2020-01-15 10:00 ` Roger Pau Monné
2020-01-15 10:18 ` Jan Beulich
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