Module sync 

Arc<T, A> — atomically reference-counted handle backed by A.

Non-intrusive: the refcount lives in a heap-allocated ArcInner<T> header (8 bytes), not on the payload T. Mirrors std Arc’s shape (new_in, strong_count, get_mut, make_mut, as_ptr, ptr_eq, allocator, Deref<Target = T>, Clone, Drop). No Weak — none of the workspace’s current consumers want one.

allocator-api2 0.2 does not ship an Arc, so we write our own against the api2 Allocator trait.

Structs

Arc

Atomically reference-counted handle to a T allocated by A.