This module implements tagged pointers.
In order to utilize the pointer packing, you must have two types: a pointer, and a tag.
The pointer must implement the
Pointer trait, with the primary requirement
being conversion to and from a usize. Note that the pointer must be
dereferenceable, so raw pointers generally cannot implement the
trait. This implies that the pointer must also be nonzero.
Many common pointer types already implement the
The tag must implement the
Tag trait. We assert that the tag and
are compatible at compile time.