[FFmpeg-cvslog] configure: more properly disable header when check_header_oc() fails

[Reimar Döffinger]

On Sun, Apr 06, 2014 at 01:02:11PM +0200, Reimar Döffinger wrote:
> On Sun, Apr 06, 2014 at 12:49:31PM +0200, Thilo Borgmann wrote:
> > Am 05.04.14 13:48, schrieb Michael Niedermayer:
> > > ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sat Apr  5 13:29:28 2014 +0200| [323c049c7e43cb610e3c5ffbe09fc46278808ad5] | committer: Michael Niedermayer
> > > 
> > > configure: more properly disable header when check_header_oc() fails
> > > 
> > > This should make no difference currently
> > > 
> > > Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> > > 
> > >> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=323c049c7e43cb610e3c5ffbe09fc46278808ad5
> > > ---
> > > [...]
> > 
> > 
> > configure fails detection for ICC compilers, because giving an .m file does not
> > produce an error (this might also be true for the microsoft compiler also
> > failing on FATE, I can't check):
> > 
> > 
> > fate at FATE-01:~/FFmpeg$ /opt/intel/composerxe-2011.4.191/bin/intel64/icc
> > -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
> > -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600 -std=c99 -fomit-frame-pointer
> > -pthread -c -o test test.m && echo OK
> > icc: warning #10147: no action performed for specified file(s)
> > OK
> 
> What idiot thought this a good idea...
> 
> > I still don't have a better idea how to handle it generically, though.
> > Checking with "check_header" at least only fails on Mac OS X >= 10.7 running
> > GCC, IIRC.
> 
> Trivially: try both .c and .m.

Plus, a bit risky but you could make check_header fail even when the
compiler only prints a warning.
There is some sense in not enabling features when the feature check
already creates warnings. (But as said, it is a bit risky, since who
knows what future compilers might warn about)