[FFmpeg-devel] [PATCH] avutil/pixdesc: add av_warn_unused_result to av_pix_fmt_get_chroma_sub_sample

[Ganesh Ajjanagadde]

On Fri, Oct 16, 2015 at 11:39 AM, Michael Niedermayer
<michael at niedermayer.cc> wrote:
> On Thu, Oct 15, 2015 at 07:20:30PM -0400, Ganesh Ajjanagadde wrote:
>> This will trigger a bunch of warnings (rightfully so). This API has been
>> abused, see the Doxygen comment above for what to do if the error code
>> is not meant to be checked.
>>
>> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
>> ---
>>  libavutil/pixdesc.h | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/libavutil/pixdesc.h b/libavutil/pixdesc.h
>> index a6056fe..975fbf2 100644
>> --- a/libavutil/pixdesc.h
>> +++ b/libavutil/pixdesc.h
>> @@ -297,6 +297,7 @@ enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc);
>>   *
>>   * @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
>>   */
>> +av_warn_unused_result
>>  int av_pix_fmt_get_chroma_sub_sample(enum AVPixelFormat pix_fmt,
>>                                       int *h_shift, int *v_shift);
>
> if the caller knows the pixel format is valid (and non hw accel) then
> there is no need to check the return code
> in many cases this is true, like a decoder that set the pix_fmt itself
> it can be sure all possible values are valid

See the Doxygen right above (this is why I pointed to it in the commit
message) - you are right, but for such "guaranteed safety" usage there
is a different API in avcodec. It seems to have been created precisely
for this purpose.

>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> No human being will ever know the Truth, for even if they happen to say it
> by chance, they would not even known they had done so. -- Xenophanes
>
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