[FFmpeg-devel] [PATCH] avutil/mem_internal: Don't use alignas for MSVC

[Zhao Zhili]

> On Dec 2, 2024, at 20:11, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
> 
> On Mon, Dec 2, 2024 at 11:28 AM Zhao Zhili
> <quinkblack-at-foxmail.com at ffmpeg.org> wrote:
>> 
>> 
>>> On Dec 2, 2024, at 00:53, James Almer <jamrial at gmail.com> wrote:
>>> 
>>> On 11/30/2024 6:13 AM, Zhao Zhili wrote:
>>>> From: Zhao Zhili <zhilizhao at tencent.com>
>>>> MSVC messed up standard C features, again.
>>>> ---
>>>> libavutil/mem_internal.h | 4 ++++
>>>> 1 file changed, 4 insertions(+)
>>>> diff --git a/libavutil/mem_internal.h b/libavutil/mem_internal.h
>>>> index 249ec3a642..2eb4aef5b0 100644
>>>> --- a/libavutil/mem_internal.h
>>>> +++ b/libavutil/mem_internal.h
>>>> @@ -78,6 +78,10 @@
>>>>     #define DECLARE_ALIGNED_T(n,t,v)    alignas(FFMIN(n, 16)) t v
>>>>     #define DECLARE_ASM_ALIGNED(n,t,v)  alignas(FFMIN(n, 16)) t av_used v
>>>>     #define DECLARE_ASM_CONST(n,t,v)    alignas(FFMIN(n, 16)) static const t av_used v
>>>> +#elif defined(_MSC_VER)
>>>> +    #define DECLARE_ALIGNED_T(n,t,v)    __declspec(align(n)) t v
>>>> +    #define DECLARE_ASM_ALIGNED(n,t,v)  __declspec(align(n)) t v
>>>> +    #define DECLARE_ASM_CONST(n,t,v)    __declspec(align(n)) static const t v
>>>> #else
>>>>     #define DECLARE_ALIGNED_T(n,t,v)    alignas(n) t v
>>>>     #define DECLARE_ASM_ALIGNED(n,t,v)  alignas(n) t av_used v
>>> 
>>> Ok.
>> 
>> I have tested with different msvc version on godbolt.org <http://godbolt.org/>.
>> 
>> MSVC v19.25 VS16.5 and below doesn’t support alignas.
>> 
>> Since v19.25 VS16.7 the build seems fine. And fate-test on my machine with VS2022 have no problem.
>> 
>> Does anyone get other problems with MSVC alignas support?
>> 
> 
> Current master doesn't pass fate on the latest VS2022 for me right here.
> I've been trying to look into whats going on, but haven't had the
> time, so please push this in the meantime.

Pushed, sorry for the break.

> 
> - Hendrik
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