rustc-ap-arena 409.0.0

Automatically published version of the package `arena` in the rust-lang/rust repository from commit bc44841ad2a2ad5f6c5e67b9e35ed8e7e71d4dc7 The publishing script for this crate lives at: https://github.com/alexcrichton/rustc-auto-publish

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.