std::scoped_thread_local!

macro_rules! scoped_thread_local {
    (static $name:ident: $t:ty) => { ... };
    (pub static $name:ident: $t:ty) => { ... };
}

Unstable (thread_local_internals #0)

: should not be necessary

Declare a new scoped thread local storage key.

This macro declares a static item on which methods are used to get and set the value stored within.

See ScopedKey documentation for more information.