The new allocators, some corner cases of the destroy and destructors, not everything on Phobos is @nogc friendly, BetterC still chockes on many common C extensions, DIP 1000, the whole set of @live semantics.
Now there is a new GC being redesigned, and there are discussions about a possible Phobos V3.
Now there is a new GC being redesigned, and there are discussions about a possible Phobos V3.