I'm about to blow your mind here: Rust has never had a GC. Managed pointers were always backed by reference counting, and the cycle collector stopped working sometime in 2010 and was never brought back online. Note that I said "were backed by reference counting" (emphasis mine), because managed pointers no longer exist in the language (unless you turn on the backwards-compatibility flag for them, which is only being provided temporarily).

So there's no longer even special syntax for a theoretical GC. Instead the plan is to greatly expand our support for custom pointer types in general, which will make all user-provided pointer types (implemented in whatever libraries our users come up with) first-class citizens. Our own stdlib will include several pointer types of this nature, including: `Rc` (reference counting), `Arc` (atomic (thread-safe) reference counting), `RWArc` (memory-safe Arc for mutable objects), and, yes, a `Gc` type.

And while it's true that we may provide hooks into the runtime to allow the `Gc` type to be implemented more efficiently, any user library will be able to use these hooks to implement its own GC. There won't be any implementation in the language itself.

The special language syntax is being removed. Its now just a library.