Thanks very much Jacob, like this I was already successful, directly invoking DMD, but my question is how can you do that using DUB as it seems to be an incredible handy tool to compile D programs. I was just struggling for a few hours getting DUB to pass the -framework switches on to GCC, I tried any possible combination. So far I was not peeking at the DUB source code, as I was figuring that it should be possible.
BTW, in the past I have already been successful using you fork of DMD and build a minimal Cocoa application. I hopefully will be able to contribute to the OSX toolchain for D soon.
Best and thanks again!