Raw string manipulation in D's mixins is much more limited than in CPP, and it's also not the only tool available for metaprogramming.

https://dlang.org/mixin.html

> constexpr means C++ also has static if, compile time loops, function eval, etc.

It's still not quite the same. I'm sorry to not bring examples, but if you look for them yourself, I think you'll find that D's metaprogramming looks nicer than C++'s constexpr.