rustc-ap-arena 645.0.0

The arena, a fast but limited type of allocator. Arenas are a type of allocator that destroy the objects within, all at once, once the arena itself is destroyed. They do not support deallocation of individual objects while the arena itself is still alive. The benefit of an arena is very fast allocation; just a pointer bump. This crate implements `TypedArena`, a simple arena that can only hold objects of a single type.