[FFmpeg-devel] [PATCH] fix few compiler warnings

Ronald S. Bultje rsbultje at gmail.com
Tue May 24 22:04:17 CEST 2016


Hi,

On Tue, May 24, 2016 at 2:00 PM, Michael Niedermayer <michael at niedermayer.cc
> wrote:

> On Mon, May 23, 2016 at 03:06:35PM +0200, Hendrik Leppkes wrote:
> > On Mon, May 23, 2016 at 1:59 PM, Michael Niedermayer
> > <michael at niedermayer.cc> wrote:
> > > On Mon, May 23, 2016 at 07:24:23AM -0400, Ronald S. Bultje wrote:
> > >> Hi,
> > >>
> > >> On Sun, May 22, 2016 at 11:39 PM, Michael Niedermayer <
> > >> michael at niedermayer.cc> wrote:
> > >>
> > >> > On Sun, May 22, 2016 at 01:51:05AM +0000, Davinder Singh wrote:
> > >> > > On Sun, May 22, 2016 at 2:09 AM Michael Niedermayer
> > >> > <michael at niedermayer.cc>
> > >> > > wrote:
> > >> > >
> > >> > > > On Sat, May 21, 2016 at 02:21:17PM +0000, Davinder Singh wrote:
> > >> > > > > hi,
> > >> > > > >
> > >> > > > > this patch fixes following compiler warnings:
> > >> > > > >
> > >> > > > > libavcodec/cfhd.c:346:78: warning: format specifies type
> 'unsigned
> > >> > short'
> > >> > > > > but the argument has type 'int' [-Wformat]
> > >> > > > >             av_log(avctx, AV_LOG_DEBUG, "Small chunk length
> %"PRIu16"
> > >> > > > > %s\n", data * 4, tag < 0 ? "optional" : "required");
> > >> > > > >                                                             ~~
> > >> > > > >   ^~~~~~~~
> > >> > > > > libavcodec/cfhd.c:472:110: warning: format specifies type
> 'unsigned
> > >> > > > short'
> > >> > > > > but the argument has type 'int' [-Wformat]
> > >> > > > >             av_log(avctx, AV_LOG_DEBUG, "Start of lowpass
> coeffs
> > >> > > > component
> > >> > > > > %"PRIu16" height:%d, width:%d\n", s->channel_num,
> lowpass_height,
> > >> > > > > lowpass_width);
> > >> > > > >
> > >> > > > >  ~~                                ^~~~~~~~~~~~~~
> > >> > > > > libavcodec/cfhd.c:490:77: warning: format specifies type
> 'unsigned
> > >> > short'
> > >> > > > > but the argument has type 'int' [-Wformat]
> > >> > > > >             av_log(avctx, AV_LOG_DEBUG, "Lowpass coefficients
> > >> > > > %"PRIu16"\n",
> > >> > > > > lowpass_width * lowpass_height);
> > >> > > > >
>  ~~
> > >> > > > >  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >> > > > >
> > >> > > > >
> > >> > > > >
> > >> > > > > libavcodec/dv_tablegen.c:30:60: warning: format specifies type
> > >> > 'char' but
> > >> > > > > the argument has type 'uint32_t' (aka 'unsigned int')
> [-Wformat]
> > >> > > > >                    "{0x%"PRIx32", %"PRId8"}", data[i].vlc,
> > >> > data[i].size)
> > >> > > > >
> > >> >
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
> > >> > > > > libavcodec/tableprint.h:37:29: note: expanded from macro
> > >> > > > > 'WRITE_1D_FUNC_ARGV'
> > >> > > > >        printf(" "fmtstr",", __VA_ARGS__);\
> > >> > > > >                             ^~~~~~~~~~~
> > >> > > > > libavcodec/dv_tablegen.c:30:60: warning: format specifies type
> > >> > 'char' but
> > >> > > > > the argument has type 'uint32_t' (aka 'unsigned int')
> [-Wformat]
> > >> > > > >                    "{0x%"PRIx32", %"PRId8"}", data[i].vlc,
> > >> > data[i].size)
> > >> > > > >
> > >> >
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
> > >> > > > >
> > >> > > > >
> > >> > > > >
> > >> > > > > libavfilter/af_hdcd.c:896:57: warning: shifting a negative
> signed
> > >> > value
> > >> > > > is
> > >> > > > > undefined [-Wshift-negative-value]
> > >> > > > >             state->readahead = readaheadtab[bits & ~(-1 <<
> 8)];
> > >> > > > >
> > >> > > > >
> > >> > > > >
> > >> > > > > libavfilter/vf_hwdownload.c:59:5: warning: ignoring return
> value of
> > >> > > > > function declared with warn_unused_result attribute
> [-Wunused-result]
> > >> > > > >     ff_formats_ref(infmts,  &avctx->inputs[0]->out_formats);
> > >> > > > >     ^~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >> > > > > libavfilter/vf_hwdownload.c:60:5: warning: ignoring return
> value of
> > >> > > > > function declared with warn_unused_result attribute
> [-Wunused-result]
> > >> > > > >     ff_formats_ref(outfmts, &avctx->outputs[0]->in_formats);
> > >> > > > >     ^~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >> > > > >
> > >> > > > >
> > >> > > > >
> > >> > > > > libavutil/opencl.c:456:17: warning: variable 'kernel_source'
> is used
> > >> > > > > uninitialized whenever 'for' loop exits because its condition
> is
> > >> > false
> > >> > > > > [-Wsometimes-uninitialized]
> > >> > > > >     for (i = 0; i < opencl_ctx.kernel_code_count; i++) {
> > >> > > > >                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >> > > > > libavutil/opencl.c:466:10: note: uninitialized use occurs here
> > >> > > > >     if (!kernel_source) {
> > >> > > > >          ^~~~~~~~~~~~~
> > >> > > > > libavutil/opencl.c:456:17: note: remove the condition if it
> is always
> > >> > > > true
> > >> > > > >     for (i = 0; i < opencl_ctx.kernel_code_count; i++) {
> > >> > > > >                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >> > > > > libavutil/opencl.c:448:30: note: initialize the variable
> > >> > 'kernel_source'
> > >> > > > to
> > >> > > > > silence this warning
> > >> > > > >     const char *kernel_source;
> > >> > > > >                              ^
> > >> > > > >                               = NULL
> > >> > > >
> > >> > > > >  libavcodec/cfhd.c           |    6 +++---
> > >> > > > >  libavcodec/dv_tablegen.c    |    2 +-
> > >> > > > >  libavfilter/af_hdcd.c       |    2 +-
> > >> > > > >  libavfilter/vf_hwdownload.c |    6 ++++--
> > >> > > > >  libavutil/opencl.c          |    2 +-
> > >> > > >
> > >> > > > please split this patch
> > >> > > > the fixed warnings are unrelated to each other and possibly
> differnt
> > >> > > > developers would like to reply to different parts
> > >> > > >
> > >> > > > [...]
> > >> > > >
> > >> > > > --
> > >> > > > Michael     GnuPG fingerprint:
> 9FF2128B147EF6730BADF133611EC787040B0FAB
> > >> > > >
> > >> > > > I have often repented speaking, but never of holding my tongue.
> > >> > > > -- Xenocrates
> > >> > > > _______________________________________________
> > >> > > > ffmpeg-devel mailing list
> > >> > > > ffmpeg-devel at ffmpeg.org
> > >> > > > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> > >> > > >
> > >> >
> > >> > >  af_hdcd.c |    2 +-
> > >> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >> > > 0ff76093ae99c1ef8ae87b70d8bf5b6ef92c43b9
> > >> > 0003-libavfilter-af_hdcd-fixed-negative-signed-value-shif.patch
> > >> > > From c498d1a86f3cdbed94cc8bc4a9af7c87af03b275 Mon Sep 17 00:00:00
> 2001
> > >> > > From: dsmudhar <ds.mudhar at gmail.com>
> > >> > > Date: Sun, 22 May 2016 06:18:58 +0530
> > >> > > Subject: [PATCH 3/7] libavfilter/af_hdcd: fixed negative signed
> value
> > >> > shift
> > >> > >
> > >> > > ---
> > >> > >  libavfilter/af_hdcd.c | 2 +-
> > >> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >> > >
> > >> > > diff --git a/libavfilter/af_hdcd.c b/libavfilter/af_hdcd.c
> > >> > > index 041b89f..fbf0836 100644
> > >> > > --- a/libavfilter/af_hdcd.c
> > >> > > +++ b/libavfilter/af_hdcd.c
> > >> > > @@ -893,7 +893,7 @@ static int integrate(hdcd_state_t *state, int
> *flag,
> > >> > const int32_t *samples, int
> > >> > >          state->code_counterC++;
> > >> > >      } else {
> > >> > >          if (bits)
> > >> > > -            state->readahead = readaheadtab[bits & ~(-1 << 8)];
> > >> > > +            state->readahead = readaheadtab[bits & ~((unsigned)
> -1 <<
> > >> > 8)];
> > >> > >          else
> > >> >
> > >> > applied
> > >>
> > >>
> > >> This is very obfuscated, why doesn't this just say bits & 0xff?
> > >
> > > i dont know that
> > > maybe the author of the original "& ~(-1 << 8)" or new code had a
> > > reason to prefer this style
> > >
> > > also obfuscation is in the eye of the beholder,
> > > i would guess 0xff is only clearer if you know what it is in binary
> > > if you dont then explicitly building it from a shift by 8 is clearer
> > > i suspect
> > >
> >
> > So he wouldn't know what 0xff is, but he does know what casting -1 to
> > unsigned produces?
> > Seems like an odd argument to me. 0xff is far clearer than some odd
> > shift and not construct.
>
> replaced by 0xff


Thanks.

Ronald


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