Macro define_thread_local_arena 

macro_rules! define_thread_local_arena {
    (
        $(#[$meta:meta])*
        $vis:vis $name:ident,
        $map:ty,
        $state_name:ident
    ) => { ... };
}

Macro to define a thread-local arena with a specific map type.

This creates a zero-sized struct implementing ThreadLocalArenaOps, providing all arena methods via the trait’s default implementations.

Example

define_thread_local_arena!(
    /// My custom thread-local arena.
    pub MyArena,
    BTreeMap<usize, Entry>,
    MY_ARENA_STATE
);