[FFmpeg-devel] [PATCH 4/5] avfilter: avoid zero arguments to variadic macro

[Michael Niedermayer]

On Sat, Oct 24, 2015 at 02:01:07PM -0400, Ganesh Ajjanagadde wrote:
> On Sat, Oct 24, 2015 at 1:48 PM, Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> > On Sat, Oct 24, 2015 at 03:52:25PM +0200, Nicolas George wrote:
> >> Le tridi 3 brumaire, an CCXXIV, Ganesh Ajjanagadde a écrit :
> >> > Thanks for the super quick review. Will apply shortly. Do you (or
> >> > others) think adding -Wgnu-zero-variadic-macro-arguments to configure
> >> > is a good idea?
> >>
> >> Considering that each additional option takes ~15 ms in configure on a
> >> fairly powerful box, not counting maintenance burden, I would say rather no.
> >
> > about 10ms here with
> >     time ./configure
> > about 1.5ms here with
> >     time ./configure --cc='ccache gcc'  --tempprefix=/home/michael/ffconftemp
> >
> > also we could speed configure up with something like this:
> > (or a more generic "all before each" checker)
> >
> > diff --git a/configure b/configure
> > index a38b290..6fa3273 100755
> > --- a/configure
> > +++ b/configure
> > @@ -5637,6 +5637,9 @@ disabled iconv || check_func_headers iconv.h iconv || check_lib2 iconv.h iconv -
> >  enabled debug && add_cflags -g"$debuglevel" && add_asflags -g"$debuglevel"
> >
> >  # add some useful compiler flags if supported
> > +if ! check_cflags -Wdeclaration-after-statement -Wall -Wdisabled-optimization -Wpointer-arith -Wredundant-decls \
> > +                  -Wwrite-strings -Wtype-limits -Wundef -Wmissing-prototypes -Wno-pointer-to-int-cast -Wstrict-prototypes -Wempty-body ; then
> > +
> >  check_cflags -Wdeclaration-after-statement
> >  check_cflags -Wall
> >  check_cflags -Wdisabled-optimization
> > @@ -5649,6 +5652,9 @@ check_cflags -Wmissing-prototypes
> >  check_cflags -Wno-pointer-to-int-cast
> >  check_cflags -Wstrict-prototypes
> >  check_cflags -Wempty-body
> > +#Note, if you add a check_cflags here, also add it to the if above
> > +fi
> > +
> >  enabled extra_warnings && check_cflags -Winline
> >
> >  check_disable_warning(){
> 
> Will leave it to you (or others) for such patches (to speed up
> configure and/or add warnings), I am fine either way.

i can apply above code if wanted, beyond that ill leave it to
others as well, like for writing a nice generic
"all before each" checker
as in
check_each check_cflags -Wdeclaration-after-statement -Wall -Wdisabled-optimization -Wpointer-arith -Wredundant-decls

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

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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