[MPlayer-dev-eng] include dirs ordering: build errors related to #include <png.h>

[Roberto Togni]

On Tue, 17 Jul 2007 07:18:47 +0300
Uoti Urpala <uoti.urpala at pp1.inet.fi> wrote:

> On Mon, 2007-07-16 at 22:00 -0500, SciFi wrote:
[...]
> 
> Rather the problem is that the name libavcodec/png.h conflicts with the
> system header. This is not something that could be automatically
> resolved by using any particular method of configuring the include path.
> 
> 
> You could first attempt to solve this generally (rather than
> reordering/changing the include path on a file-by-file basis) by not
> having libavcodec in the include path to avoid picking its private
> headers accidentally and using "#include "libavcodec/foo.h" to
> intentionally include them. Unfortunately avformat.h in libavformat/
> uses '#include "avcodec.h"'. That can't work unless avcodec.h is either
> in the same directory as avformat.h or avcodec.h is in the include path.
> So just dropping libavcodec/ from the include path will fail at least
> for files which include avformat.h.
> 
> This could be fixed quite nicely using gccs -iquote instead of -I for
> avcodec. Then the headers in avcodec would not be confused with anything
> included with <>, and the option would also make sense semantically -
> headers in libavcodec/ are not part of the installed header namespace.
> Unfortunately other compilers lack support for this.
> 
> Another way would be to copy/link the "installed" headers from FFmpeg to
> a new directory as a part of the build process. Then avformat.h and
> avcodec.h would be in the same directory and the avformat->avcodec
> dependency would work independently of include path. This would be
> somewhat ugly but might work OK in practice. As long as there aren't
> more files including avformat.h (currently there seem to be 3) it's
> probably simpler to use a custom include path for those though.
> 

The same kind of problem is reported with libdca 0.0.5, the dts.h header
includes dca.h, and it conflicts with libavcodec/dca.h.
What about addinh -Ilibavcodec and/or -Ilibavformat only to the files
that really need them? It could eventually be done automatically by
configure with some grep magic. Any better ideas?

Ciao,
 Roberto