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Re: [Xen-devel] Ping: [PATCH v2] dom0-build: fix build with clang5
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@xxxxxxxx>
---
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@xxxxxxx>
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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