>These changes should be in another pull.

Ok
>+1 - what exactly is this solving?

This need for properly const(Class) mangling:
When argumeng has a const(Class) type it should be mangled as const(Class)*, but if argument has a const(Class)*, for example, it should be mangled as const(Class*)*.
In other words, we map D const class to C++ const pointer to a const class, but in function arguments top const modifer is removed.