[Kde-games-devel] KgSound build problem

[Ian Wadham]

Please see diagnosis below + attached patch.

On 20/04/2012, at 5:18 PM, Ian Wadham wrote:

> After svn update of kdegames I get build problems where CMake says
> that my version of libsndfile is too old and that I need at least v 0.21.
> In actual fact I have v 1.0.25. 
> 
> I had a look at kdegames/libkdegames/CMakeLists.txt and added two
> lines, just before "try_compile", to see what is happening:
> 
> if (SNDFILE_FOUND AND USE_OPENAL_SNDFILE)
>    message(STATUS "Checking libsndfile capabilities")
>    message(STATUS "SNDFILE_INCLUDE_DIR <" ${SNDFILE_INCLUDE_DIR} "> SNDFILE_INCLUDE_DIRS <" ${SNDFILE_INCLUDE_DIRS} ">")
>    message(STATUS "SNDFILE_LIBRARY <" ${SNDFILE_LIBRARY} "> SNDFILE_LIBRARIES <" ${SNDFILE_LIBRARIES} ">")
>    try_compile(SNDFILE_WORKS
>        ${CMAKE_CURRENT_BINARY_DIR}/audio/check-libsndfile-capabilities
>        ${CMAKE_CURRENT_SOURCE_DIR}/audio/check-libsndfile-capabilities.cpp)
> 
> Note the messages put out both singular and plural forms of the INCLUDE and LIBRARY
> symbols.  This is because both singular and plural forms occur later in the CMakeLists.txt
> and I think there may have been a slip of the pen somewhere in there.
> 
> Attached is my CMake output.  It appears (in that output) that the singular 
> SNDFILE_INCLUDE_DIR and the plural SNDFILE_LIBRARIES are correct and
> the header and libraries are where I expect to find them.  I am working on a
> Macbook with libraries installed by Macports, as I have been doing from July
> last year until today, without any problems.
> 
> Furthermore, my installed sndfile.h file contains the necessary OGG and VORBIS
> enum values.   The only other thing I can think of is that the compiler here does not like
> 
> int main()
> {
>        //We need Ogg/Vorbis support. If sndfile.h is too old, these enum values
>        //will be missing and compiler errors will be generated.
>        (void) SF_FORMAT_OGG;
>        (void) SF_FORMAT_VORBIS;
> 
>        return 0;
> }
> 
> in libkdegames/audio/check-libsndfile-capabilities.cpp … "(void) <enum value>;"(?)

I think there was a chicken-and-egg problem in the "try_compile" command to CMake (see
above). ${CMAKE_CURRENT_SOURCE_DIR}/audio/check-libsndfile-capabilities.cpp has
a "#include <sndfile.h>" in it, but "try_compile" does not know where to find that header,
unless perhaps there is a cache handy, so SNDFILE_WORKS will always be false if you
are building in an empty build directory (as I was).

The attached patch gives "try_compile" an include-path, adds some informative comments
about sound to the CMake log and fixes a plural (SNDFILE_INCLUDE_DIRS) later in the build.

Cheers, Ian W.

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