No warnings is the whole point. My c++ isn't so good that I understand that first one, but if->while and break->"" can introduce infinite loops, else->"" will

No warnings is the whole point. My c++ isn't so good that I understand that first one, but if->while and break->"" can introduce infinite loops, else->"" will break logic (and possibly hit null pointers), double->float will cause subtle rounding errors in numeric computation, and volatile->"" will break multi-threaded apps unpredictably. It's evil, subtle code breakage that because of the macro (in an included header far far away) leave the code looking perfectly ordinary.