[FFmpeg-devel] [PATCHv2] avfilter/buffersrc: add av_warn_unused_result attributes

[Ganesh Ajjanagadde]

On Wed, Oct 7, 2015 at 10:01 AM, Clément Bœsch <u at pkh.me> wrote:
> On Wed, Oct 07, 2015 at 09:31:49AM -0400, Ganesh Ajjanagadde wrote:
>> On Wed, Oct 7, 2015 at 8:59 AM, Clément Bœsch <u at pkh.me> wrote:
>> > On Tue, Oct 06, 2015 at 06:53:47PM -0400, Ganesh Ajjanagadde wrote:
>> >> This adds av_warn_unused_result whenever it is relevant.
>> >>
>> >> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
>> >> ---
>> >>  libavfilter/buffersrc.h | 3 +++
>> >>  1 file changed, 3 insertions(+)
>> >>
>> >> diff --git a/libavfilter/buffersrc.h b/libavfilter/buffersrc.h
>> >> index cd3d95f..847c093 100644
>> >> --- a/libavfilter/buffersrc.h
>> >> +++ b/libavfilter/buffersrc.h
>> >> @@ -78,6 +78,7 @@ unsigned av_buffersrc_get_nb_failed_requests(AVFilterContext *buffer_src);
>> >>   * This function is equivalent to av_buffersrc_add_frame_flags() with the
>> >>   * AV_BUFFERSRC_FLAG_KEEP_REF flag.
>> >>   */
>> >> +av_warn_unused_result
>> >>  int av_buffersrc_write_frame(AVFilterContext *ctx, const AVFrame *frame);
>> >>
>> >>  /**
>> >> @@ -98,6 +99,7 @@ int av_buffersrc_write_frame(AVFilterContext *ctx, const AVFrame *frame);
>> >>   * This function is equivalent to av_buffersrc_add_frame_flags() without the
>> >>   * AV_BUFFERSRC_FLAG_KEEP_REF flag.
>> >>   */
>> >> +av_warn_unused_result
>> >>  int av_buffersrc_add_frame(AVFilterContext *ctx, AVFrame *frame);
>> >>
>> >>  /**
>> >> @@ -115,6 +117,7 @@ int av_buffersrc_add_frame(AVFilterContext *ctx, AVFrame *frame);
>> >>   * @return            >= 0 in case of success, a negative AVERROR code
>> >>   *                    in case of failure
>> >>   */
>> >> +av_warn_unused_result
>> >>  int av_buffersrc_add_frame_flags(AVFilterContext *buffer_src,
>> >>                                   AVFrame *frame, int flags);
>> >>
>> >
>> > Aren't you just supposed to (void)-prefix the call in the caller when you
>> > explicitly don't care about the result?
>> >
>> > These functions certainly looks like you actually want to check for the
>> > result most of the time.
>>
>> Exactly - this addition to the declaration in the header will trigger
>> a warning whenever this function is used without obtaining the return
>> value.
>>
>
> Oh, my bad, I misunderstood, sounds indeed saner than what I had in mind.
>
> Thanks for the clarification.

By the way, I highly encourage all developers to slowly start adding
this to relevant headers, at least in the things they respectively
maintain. For instance, a bunch of possible bugs/robustness issues
will be fixed. Here is one I noticed today: by applying to
init_get_bits8, a few warnings get triggered. There have been commits
from Michael addressing some CID's related to this - this will ensure
a complete weeding out of that particular issue.

>
> --
> Clément B.
>
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