I was one of the original developers behind the AuroraUX project. I left fairly early on as it was clear it would be a mismanaged disaster (we changed SCM three times before I had even finished initial planning).

About a decade later and, despite my initial work, no one did ever get GNAT and GIGI yanked off GCC, let alone put onto LLVM.

For the record, I think this is a bad idea now. GNAT and GIGI are awful and need to be replaced. GCC does a good job at executable code generation, and is generally competitive with LLVM. LLVM seems to have some better stuff for front-end designers that cause me to still favor it, but that's a different matter.