Module arena 

Generic index-based arena for AST nodes.

Replaces Box<T> with a Copy integer handle (Id<T>) into a flat Vec<T> owned by an Arena<T>. Every Id<T> is tagged with the id of the arena it was allocated from, so using it against the wrong arena panics immediately at the access site instead of silently reading unrelated data or panicking later with a confusing out-of-bounds error.

Structs

Arena

Flat backing store for T, indexed by Id<T>.

Id

A typed, Copy handle into a specific Arena<T>.

Statics

NEXT_ARENA_ID 🔒

Global counter handing out a unique id to every Arena<T> that’s ever constructed, so Id<T>s can be checked against their origin arena.