@alalazo I tried something like this but it isn't allowed:

    variant('build_type', default='',                             
            description='The build type to build',                              
            values=('')) 

This current solution is kind of hacky (-DCMAKE_BUILD_TYPE is added twice and the second instance wins). It would be good to be able to support this, although I've never seen a CMake package that doesn't let you set this value to something.