A different, precise TLS garbage collector?

[Etienne Cimon via Digitalmars-d]

This GC model also seems to work fine for locally-allocated __gshared 
objects. Since they're registered locally but available globally, 
they'll be collected once the thread that created it is gone.

Also, when an object is cast(shared) before being sent to another 
thread, it's usually still in scope once the other thread returns.

So there seems to be some very thin chances that existing code will be 
broken with a thread-local GC.