Re: [dpdk-dev] mlx debug build error with clang

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 6/16/2017 3:49 PM, Ferruh Yigit wrote:
> On 6/16/2017 1:58 PM, Ferruh Yigit wrote:
>> On 6/16/2017 1:19 PM, Adrien Mazarguil wrote:
>>> Hi Ferruh,
>>>
>>> On Tue, Jun 13, 2017 at 04:32:03PM +0100, Ferruh Yigit wrote:
>>>> Hi Adrien, Nelio,
>>>>
>>>> I am getting following build error [1] with clang [2] when debug enabled
>>>> for mlx4 and mlx5.
>>>>
>>>> This started after I update my box, not sure what triggered this.
>>>> Can you please help fixing this?
>>>>
>>>> Thanks,
>>>> ferruh
>>>>
>>>>
>>>> [1]
>>>>
>>>> .../drivers/net/mlx4/mlx4_flow.c:731:3: error: use of GNU statement
>>>> expression extension [-Werror,-Wgnu-statement-expression]
>>>>                 claim_zero(ibv_destroy_qp(fdq->qp));
>>>>                 ^
>>>> .../drivers/net/mlx4/mlx4.h:185:25: note: expanded from macro 'claim_zero'
>>>> #define claim_zero(...) assert((__VA_ARGS__) == 0)
>>>>                         ^
>>>> /usr/include/assert.h:95:6: note: expanded from macro 'assert'
>>>>     ({                                                                  \
>>>>      ^
>>>>
>>>> ....
>>>>
>>>> .../drivers/net/mlx5/mlx5_fdir.c:278:2: error: use of GNU statement
>>>> expression extension [-Werror,-Wgnu-statement-expression]
>>>>         assert(((uint8_t *)attr + sizeof(*attr)) == (uint8_t *)spec_offset);
>>>>         ^
>>>> /usr/include/assert.h:95:6: note: expanded from macro 'assert'
>>>>     ({                                                                  \
>>>>      ^
>>>>
>>>> [Many of similar ...]
>>>>
>>>>
>>>> [2]
>>>> target: x86_64-native-linuxapp-clang
>>>>
>>>> clang version 4.0.0 (tags/RELEASE_400/final)
>>>
>>> Recent Glibc versions now apparently handle assert() through a nonstandard
>>> ({ }) construct, which is not pedantic-safe due to a missing __extension__
>>> keyword.
>>>
>>> assert.h still provides a standard assert() definition that shouldn't cause
>>> compilation to fail when the following condition is met:
>>>
>>>  #if !defined __GNUC__ || defined __STRICT_ANSI__
>>>
>>> However __GNUC__ is (always?) defined by clang for maximum compatibility
>>> with GCC while __STRICT_ANSI__ is not due to the -std=gnu99 parameter,
>>> assert.h thinks it's OK to use a ({ }) construct but is then caught by
>>> clang's -pedantic parameter.
>>>
>>> There are two ways to address this issue while keeping our beloved -pedantic
>>> parameter in debug mode:
>>>
>>> 1. Replacing -std=gnu99 with -std=c99 (which is even stricter) to bring back
>>>    __STRICT_ANSI__.
>>> 2. Replacing assert() statements with RTE_ASSERT().
>>>
>>> The former should be doable now that DPDK includes have been cleaned up, and
>>> we're thinking about doing the latter at some point.
>>>
>>> Since I don't have a recent Glibc handy, can you try replacing -std=gnu99
>>> with -std=c99 in both Makefiles (mlx4 and mlx5), and report how GCC and
>>> clang fare? (GCC at least seems to have no problem with that on my side)
>>
>> Sure, I will try -std=c99
> 
> This fixes the build error.

Hi Adrien,

Are you planning to send a patch for this?

Thanks,
ferruh

> 
>>
>>>
>>
>