Most CMake based software should be fine with this (some will even refuse to build in you don't do it in a separate build dir).  IMHO, object and src should be separated. It allows for cleaner debugging and understanding what is going on.  I think the default is to not do it in a separate build dir because of compatibility reasons.  I was wonder if there was a reason you it was added so explicitly in this easyconfig. If you don't really need it, I would drop it.