Re: [kvm-unit-tests PATCH] Replace -Wextra with a saner list of warning flags

[Paolo Bonzini <pbonzini@redhat.com>]

On 29/06/2017 18:35, Andrew Jones wrote:
> On Thu, Jun 29, 2017 at 06:30:47PM +0200, Thomas Huth wrote:
>> On 29.06.2017 17:40, Thomas Huth wrote:
>>> Using -Wextra together with -Werror is troublesome - various versions
>>> of GCC produce suspicious or even wrong warnings with -Wextra which
>>> then become fatal errors with -Werror. For example, the current state
>>> of the kvm-unit-tests does not compile anymore with GCC 4.8.1 for
>>> s390x due to an inadequate -Wmissing-field-initializers warning.
>>> That's annoying for users who just would like to compile the
>>> kvm-unit-tests and cumbersome for the developers who have to work
>>> around these problems in the source code. So let's replace -Wextra
>>> by a saner lists of warning flags that are normally enabled by -Wextra.
>>> Most of them are added to the architecture independent CFLAGS list,
>>> so that x86 now benefits from these checks, too. The ones that
>>> could not be added there are placed in the architecture specific
>>> CFLAGS instead.
>>
>> BTW, I also dropped -Wunused-parameter on purpose. It's often a nuisance
>> that you are forced to add "unused" attributes to parameters, just
>> because you can not get rid of certain parameter since your function has
>> to obey a certain API. That means we could now finally also get rid of
>> the ugly "__unused" tags in the code in the lib folder again, if we like ;-)
> 
> Fine by me. Adding __unused gets tiresome and ugly. I even recently
> wrote a patch where I needed to introduce __maybe_unused...

Agreed, C should take inspiration from C++ and add

   int f(int x, int /* unused */)

Paolo