From: Julien Grall <julien@xen.org>
To: Jan Beulich <jbeulich@suse.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien.grall@arm.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] Ping: [PATCH v2] dom0-build: fix build with clang5
Date: Sat, 11 Jan 2020 16:27:17 +0000 [thread overview]
Message-ID: <90e88e64-e93e-6fff-851f-ecb8c9203516@xen.org> (raw)
In-Reply-To: <91d9f45c-e0e1-a01c-d812-2dd3345fff48@suse.com>
On 20/12/2019 16:26, Jan Beulich wrote:
> On 17.07.2019 08:47, 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 guess the disagreement on how to exactly address the issue has
> stalled this. But I think we should rather have _some_ (e.g.
> this) solution in the repo, than continue to ship versions which
> don't build. People wanting to beautify the code further could
> then submit incremental patches.
I would prefer a more readable code but for the sake of unblocking:
Acked-by: Julien Grall <julien@xen.org>
Note that clang is not officially supported to build Xen on Arm. So the
build concern is x86 only.
Cheers,
--
Julien Grall
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next prev parent reply other threads:[~2020-01-11 16:27 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
2019-07-29 11:36 ` Jan Beulich
2019-12-20 16:26 ` [Xen-devel] Ping: " Jan Beulich
2020-01-11 16:27 ` Julien Grall [this message]
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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