Re: [kvm-unit-tests PATCH] Always compile the kvm-unit-tests with -fno-common

[Thomas Huth <thuth@redhat.com>]

On 13/05/2020 12.05, Thomas Huth wrote:
> On 12/05/2020 11.55, Thomas Huth wrote:
>> The new GCC v10 uses -fno-common by default. To avoid that we commit
>> code that declares global variables twice and thus fails to link with
>> the latest version, we should also compile with -fno-common when using
>> older versions of the compiler.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  Makefile | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 754ed65..3ff2f91 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -49,7 +49,7 @@ include $(SRCDIR)/$(TEST_DIR)/Makefile
>>  cc-option = $(shell if $(CC) -Werror $(1) -S -o /dev/null -xc /dev/null \
>>                > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
>>  
>> -COMMON_CFLAGS += -g $(autodepend-flags) -fno-strict-aliasing
>> +COMMON_CFLAGS += -g $(autodepend-flags) -fno-strict-aliasing -fno-common
> 
> Oh, wait, this breaks the non-x86 builds due to "extern-less" struct
> auxinfo auxinfo in libauxinfo.h !
> Drew, why isn't this declared in auxinfo.c instead?

Oh well, it's there ... so we're playing tricks with the linker here? I
guess adding a "__attribute__((common, weak))" to auxinfo.h will be ok
to fix this issue?

 Thomas