Re: [Qemu-devel] [PATCH] clang: Disable warning about expansion to 'defined'

[Paolo Bonzini]

On 09/08/2016 10:09, Peter Maydell wrote:
> On 9 August 2016 at 03:35, Pranith Kumar <address@hidden> wrote:
>> Clang produces the following warning. The warning is detailed here:
>> https://reviews.llvm.org/D15866. Disable the warning.
>>
>> /home/pranith/devops/code/qemu/hw/display/qxl.c:507:5: warning: macro 
>> expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
>> #if SPICE_NEEDS_SET_MM_TIME
>>     ^
>> /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded 
>> from macro 'SPICE_NEEDS_SET_MM_TIME'
>>   (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06))
>>     ^
>> /home/pranith/devops/code/qemu/hw/display/qxl.c:1074:5: warning: macro 
>> expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
>> #if SPICE_NEEDS_SET_MM_TIME
>>     ^
>> /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded 
>> from macro 'SPICE_NEEDS_SET_MM_TIME'
>>   (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06))
> 
> Is this the only thing in our code which provokes the warning?
> If so, why don't we just fix it to not be undefined behaviour?

Indeed that was my first suggestion yesterday.  However, we use -Wundef
(a good idea, I think), and fixing it would cause the -Wundef warning to
appear instead.

Paolo