The main difference I see is this project seems to be using C++ (plus C macros?) directly instead of a DSL. And some llvm magic thrown in for good measure.
Fair. I think of DSLs as a way of thinking about the program you want to write; if a scheme is realizable with few compromises in an existing language, it can still be considered "DSL style". SICP calls this style "stratified design".
You can do all sorts of “stratified design” with C++ templates which I assume is underneath the covers of this system. boost::spirit is probably the most excessive use of this that I’ve seen so far.