Do you plan to support a build path that has no circular dependendencies? This would be a very strong nice to have for porting D to new architectures.
So it should be possible to build a subset of D (stage 1) with gcc without relying on a D compiler and than using the stage 1 binary to build a complete D compiler. There are languages in Debian that rely on themselves to be build and it's a headache to support those languages on all architectures. Regards, Thomas Koch