Re: [kvm-unit-tests PATCH] s390x/intercept: Fix problem with bad compiler warning

[Thomas Huth <thuth@redhat.com>]

On 27.06.2017 10:24, David Hildenbrand wrote:
> On 27.06.2017 06:18, Thomas Huth wrote:
>> The intercept test currently can not be compiled with GCC 4.8 anymore.
>> It generates the following warning (which is fatal due to -Werror):
>>
>> s390x/intercept.c: In function ‘test_stidp’:
>> s390x/intercept.c:111:9: error: missing initializer for field ‘version’ of ‘struct cpuid’ [-Werror=missing-field-initializers]
>>   struct cpuid id = {};
>>          ^
>> Fix it by using a "0" as intializer here.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  NB: We could also remove the -Wextra from the CFLAGS instead. IMHO
>>  using -Wextra together with -Werror is just like playing Russian roulette.
>>  Since -Wextra is some kind of "compiler warning playground" for the GCC
>>  folks, you never know which compiler version will trigger an unexpected
>>  (and often also unfounded) warning here, so using this together with -Werror
>>  is just a nuisance.
> 
> I agree, this is really not deterministic.
> 
>>
>>  s390x/intercept.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/s390x/intercept.c b/s390x/intercept.c
>> index 9766289..9fe86cf 100644
>> --- a/s390x/intercept.c
>> +++ b/s390x/intercept.c
>> @@ -108,7 +108,7 @@ static void test_stap(void)
>>  /* Test the STORE CPU ID instruction */
>>  static void test_stidp(void)
>>  {
>> -	struct cpuid id = {};
>> +	struct cpuid id = { 0 };
>>  
>>  	asm volatile ("stidp %0\n" : "+Q"(id));
>>  	report("type set", id.type);
>>
> 
> arm and powerpc also use -Wextra, maybe we should remove this then for all.
> 
> Whatever you prefer.

True ... maybe Drew and Laurent can also comment on whether they like
-Wextra or not ... if we all agree, then we can remove it, otherwise
let's try to go with this patch first (in the hope that we won't hit the
next problem too soon).

> Reviewed-by: David Hildenbrand <david@redhat.com>

Thanks!

 Thomas