Use of find_library

[msieben]

In certain files at https://github.com/Metrological/WebKitForWayland/tree/master/Source/cmake the find_library function is used with hardcoded names. Although the names might be commonly accepted, wouldn't it be better to extract the name from the .pc, i.e. the name given by -l? This allows for less conventional names.

Example: https://github.com/Metrological/WebKitForWayland/blob/master/Source/cmake/FindOpenGLES2.cmake#L18-20

[zdobersek]

What are the contents of the .pc file? What's the actual name of the library?

Don't know off the top of my head whether something like this is extractable from the .pc file via CMake.

[msieben]

The actual contents depends on what is put in the file. The cmake documentation [1] mentions support for extracting flags and names. For example:

<XPREFIX>_FOUND          ... set to 1 if module(s) exist
<XPREFIX>_LIBRARIES      ... only the libraries (w/o the '-l')
<XPREFIX>_LIBRARY_DIRS   ... the paths of the libraries (w/o the '-L')
<XPREFIX>_LDFLAGS        ... all required linker flags
<XPREFIX>_LDFLAGS_OTHER  ... all other linker flags
<XPREFIX>_INCLUDE_DIRS   ... the '-I' preprocessor flags (w/o the '-I')
<XPREFIX>_CFLAGS         ... all required cflags

[1] http://www.cmake.org/cmake/help/v3.0/module/FindPkgConfig.html gives

[msieben]

An example

prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${prefix}/include

Name: glesv2
Description: NAME implementation of OpenGL ESv2
Version: 1.0
Libs: -L${libdir} -lLIBNAME
Cflags: -I${includedir} -I${includedir}/LIBPATH

If LIBNAME would be extracted and used, it would be more flexible.

[zdobersek]

Would it be possible to create a libGLESv2.so symlink, that points to whatever library should be used?

[msieben]

That's currently being done.

[zdobersek]

I think that's sufficient, and perhaps even common, but I'm not against searching for the specific library names.

In the find_library() call in FindOpenGLES2.cmake that you linked before, change 'GLESv2' to '${PC_OPENGLES2_LIBRARIES}' and test it out. It might work, not sure (and can't test it myself). If it does, we can easily commit the change.

[msieben]

${PC_OPENGLES2_LIBRARIES} is more in agreement with the, already implemented, use of pkg-config. If it works, we should indeed adopt it (imho). I will keep you updated.