[FFmpeg-devel] [PATCHv3] avutil/attributes: extend av_uninit to clang

[Michael Niedermayer]

On Wed, Oct 07, 2015 at 06:22:08PM -0400, Ganesh Ajjanagadde wrote:
> Commit 6dac8c8327 disabled av_uninit for clang, due to some useless warnings.
> The concept of av_uninit is inherently useful though. This patch silences a
> bunch of warnings on clang e.g
> http://fate.ffmpeg.org/log.cgi?time=20150918181527&log=compile&slot=x86_64-darwin-clang-polly-vectorize-stripmine-3.7.
> Furthermore, it should be useful for general usage of av_uninit in future.
> 
> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> ---
>  libavutil/attributes.h | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/libavutil/attributes.h b/libavutil/attributes.h
> index 5c6b9de..ceb9e29 100644
> --- a/libavutil/attributes.h
> +++ b/libavutil/attributes.h
> @@ -147,6 +147,14 @@
>  
>  #if defined(__GNUC__) && !defined(__INTEL_COMPILER) && !defined(__clang__)
>  #    define av_uninit(x) x=x
> +#elif defined(__clang__)
> +#if __has_warning("-Wuninitialized")
> +#    define av_uninit(x) \
> +        _Pragma("clang diagnostic push") \
> +        _Pragma("clang diagnostic ignored \"-Wuninitialized\"") \
> +        x=x \
> +        _Pragma("clang diagnostic pop")
> +#endif

this breaks
make distclean ; ./configure --cc='ccache clang' && make -j12
it does not break clang alone and clearing the ccache cache does not
help
ccache version 3.1.6

In file included from libavfilter/af_aecho.c:1:
libavfilter/af_aecho.c:226:315: error: expected identifier or '('
static void echo_samples_dblp(AudioEchoContext *ctx, uint8_t **delayptrs, uint8_t * const *src, uint8_t **dst, int nb_samples, int channels) { const double out_gain = ctx->out_gain; const double in_gain = ctx->in_gain; const int nb_echoes = ctx->nb_echoes; const int max_samples = ctx->max_samples; int i, j, chan,#pragma clang diagnostic push#pragma clang diagnostic ignored "-Wuninitialized" index=index#pragma clang diagnostic pop; ((void)0); for (chan = 0; chan < channels; chan++) { const double *s = (double *)src[chan]; double *d = (double *)dst[chan]; double *dbuf = (double *)delayptrs[chan]; index = ctx->delay_index; for (i = 0; i < nb_samples; i++, s++, d++) { double out, in; in = *s; out = in * in_gain; for (j = 0; j < nb_echoes; j++) { int ix = index + max_samples - ctx->samples[j]; ix = (((ix) >= (max_samples)) ? (ix) - (max_samples) : (ix)); out += dbuf[ix] * ctx->decay[j]; } out *= out_gain; *d = av_clipd_c(out, -1.0, 1.0); dbuf[index] = in; index = (((index + 1) >= (max_samples)) ? (index + 1) - (max_samples) : (index + 1)); } } ctx->delay_index = index; }
                                                                                                                                                                                                                                                                                                                          ^

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

When the tyrant has disposed of foreign enemies by conquest or treaty, and
there is nothing more to fear from them, then he is always stirring up
some war or other, in order that the people may require a leader. -- Plato
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