[libcamera-devel] [PATCH] meson.build: Silence the C99 designators warning

[Kieran Bingham]

Hi Laurent,

On 13/02/2020 10:52, Laurent Pinchart wrote:
> Hi Kieran,
> 
> On Thu, Feb 13, 2020 at 10:35:37AM +0000, Kieran Bingham wrote:
>> On 12/02/2020 23:54, Laurent Pinchart wrote:
>>> We use array designators for array initialization, which is a C99
>>> extension. clang-10 warns about it, causing a build failure.
>>>
>>> As this is a useful extension, silence the warning. This needs to be
>>> done only if the compiler supports the -Wno-c99-designator argument,
>>> otherwise a -Wunknown-warning-option will be generated.
>>>
>>
>> As we actively use the feature, why not then set the standard
>> appropriately instead...
>>
>> index 0bbd24b2a295..7d572fa9a47a 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -5,6 +5,7 @@ project('libcamera', 'c', 'cpp',
>>          'werror=true',
>>          'warning_level=2',
>>          'cpp_std=c++14',
>> +        'c_std=c99',          # or =c11, or higher if desired [0]
>>      ],
>>      license : 'LGPL 2.1+')
>>
>> Or will that not apply because we're using C++ compilers... but then if
>> that's the case, why is our c++ compiler complaining about C features...
> 
> The option is indeed for C sources only. I'm not sure what the rationale
> is for clang++ to complain about this, but it does.
> 
> For what it's worth, ChromeOS also sets -Wno-c99-designator.
> 
>> [0] https://mesonbuild.com/Builtin-options.html#compiler-options
>>
>>> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>>> ---
>>>  meson.build | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/meson.build b/meson.build
>>> index 0bbd24b2a295..aceba997aebd 100644
>>> --- a/meson.build
>>> +++ b/meson.build
>>> @@ -60,6 +60,12 @@ if cc.get_id() == 'clang'
>>>      endif
>>>  endif
>>>  
> 
> I'll add a comment here:
> 
> # We use C99 designated initializers for arrays as C++ has no equivalent
> # feature. Both gcc and clang support this extension, but recent
> # versions of clang generate a warning that needs to be disabled.


Great, I think the comment helps a lot there.

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>


>>> +if cc.has_argument('-Wno-c99-designator')
>>> +    common_arguments += [
>>> +        '-Wno-c99-designator',
>>> +    ]
>>> +endif
>>> +
>>>  c_arguments += common_arguments
>>>  cpp_arguments += common_arguments
>>>  
> 

-- 
Regards
--
Kieran