[FFmpeg-devel] [PATCH] avcodec: use HAVE_THREADS header guards to silence -Wunused-function

[Ganesh Ajjanagadde]

On Thu, Sep 17, 2015 at 7:51 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Thu, Sep 17, 2015 at 06:54:37AM -0400, Ganesh Ajjanagadde wrote:
>> On Thu, Sep 17, 2015 at 6:17 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> > On Wed, Sep 16, 2015 at 10:22:27PM -0400, Ganesh Ajjanagadde wrote:
>> >> When compiled with --disable-pthreads, e.g
>> >> http://fate.ffmpeg.org/report.cgi?time=20150917015044&slot=alpha-debian-qemu-gcc-4.7,
>> >> a bunch of -Wunused-functions are reported due to missing header guards
>> >> around threading related functions.
>> >> This patch should silence such warnings.
>> >>
>> >> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
>> >> ---
>> >>  libavcodec/alac.c          | 2 ++
>> >>  libavcodec/exr.c           | 2 ++
>> >>  libavcodec/ffv1dec.c       | 4 ++++
>> >>  libavcodec/flacdec.c       | 2 ++
>> >>  libavcodec/h264.c          | 2 ++
>> >>  libavcodec/huffyuvdec.c    | 2 ++
>> >>  libavcodec/mdec.c          | 2 ++
>> >>  libavcodec/mimic.c         | 4 ++++
>> >>  libavcodec/mpeg12dec.c     | 2 ++
>> >>  libavcodec/mpeg4videodec.c | 2 ++
>> >>  libavcodec/pngdec.c        | 2 ++
>> >>  libavcodec/takdec.c        | 2 ++
>> >>  libavcodec/tta.c           | 2 ++
>> >>  libavcodec/vp3.c           | 4 ++++
>> >>  libavcodec/vp8.c           | 2 ++
>> >>  libavcodec/vp9.c           | 2 ++
>> >>  libavcodec/wavpack.c       | 2 ++
>> >>  17 files changed, 40 insertions(+)
>> >
>> > av_unused might be simpler to silence these warnings than #if
>>
>> I do not think this is consistent at the moment across the codebase;
>> sometimes we use header guards and sometimes we use av_unused. Please
>> tell me if what the rationale is for either of them; I am fine either
>> way. Any half decent compiler should anyway remove unused functions
>> when compiled with optimizations.
>
> #ifs will be more work to maintain as they can break build if a new
> function call or function is added. av_unused cannot break build
> #ifs also make the code harder to read, especially if there are
> already some #ifs there before
>
> #ifs make sense for non static symbols as they cannot be removed by
> the compiler or linker generally
>
> #ifs could also be used to structure code in a file if for some
> reason its unwanted to split it in several files
> #ifs also gurantee that code is removed and this makes sense in
> performance critical code
> #ifs can be used for any group of lines not just functions/variables
> as for av_unused

Ok, updated patch.

> ...
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
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>
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