[FFmpeg-devel] out tree build : possible config.h conflict

[matthieu castet]

Hi,

if you build ffmpeg in tree and then latter you decide to build out of 
tree you can have unexpected behavior :
- there will be a config.h at the base of the source directory (from the 
in tree build)
- there will be a config.h at the base of the out of tree directory.


And when building source at the base of the source directory, the bad 
config.h will be taken, because the compiler will search first in the 
source file directory.

This can be easily showed by putting a #error in the config.h of source 
directory and #warning of build directory [1]


The build system shouldn't allow out tree build in config.h is present 
in source directory or it should find a way to not include it.


Matthieu

[1]
In file included from /home/mat/appli/ffmpeg/cmdutils.c:31:
/home/mat/appli/ffmpeg/config.h:1:2: error: #error bad config
In file included from /home/mat/appli/ffmpeg/libavutil/common.h:282,
                  from /home/mat/appli/ffmpeg/libavutil/avutil.h:56,
                  from /home/mat/appli/ffmpeg/libavcodec/avcodec.h:30,
                  from /home/mat/appli/ffmpeg/libavformat/avformat.h:45,
                  from /home/mat/appli/ffmpeg/cmdutils.c:32:
./config.h:1:2: warning: #warning good config
In file included from /home/mat/appli/ffmpeg/libavutil/internal.h:37,
                  from /home/mat/appli/ffmpeg/libavutil/common.h:283,
                  from /home/mat/appli/ffmpeg/libavutil/avutil.h:56,
                  from /home/mat/appli/ffmpeg/libavcodec/avcodec.h:30,
                  from /home/mat/appli/ffmpeg/libavformat/avformat.h:45,
                  from /home/mat/appli/ffmpeg/cmdutils.c:32:
./config.h:1:2: warning: #warning good config
In file included from /home/mat/appli/ffmpeg/libavutil/timer.h:29,
                  from /home/mat/appli/ffmpeg/libavutil/internal.h:40,
                  from /home/mat/appli/ffmpeg/libavutil/common.h:283,
                  from /home/mat/appli/ffmpeg/libavutil/avutil.h:56,
                  from /home/mat/appli/ffmpeg/libavcodec/avcodec.h:30,
                  from /home/mat/appli/ffmpeg/libavformat/avformat.h:45,
                  from /home/mat/appli/ffmpeg/cmdutils.c:32:
./config.h:1:2: warning: #warning good config
In file included from /home/mat/appli/ffmpeg/libavformat/network.h:24,
                  from /home/mat/appli/ffmpeg/cmdutils.c:42:
./config.h:1:2: warning: #warning good config