Rust does have safe static variables. You just need a) to use interior mutability (`static mut` is a very strange feature that should probably never have existed) and b) to ensure that its type is `Sync` (since multiple threads can obtain references to it).

For example, use an atomic integer: https://play.rust-lang.org/?version=stable&mode=debug&editio...

You can also use types built on std::sync::Once and UnsafeCell, like once_cell::Lazy<std::sync::RwLock<T>>. This will get even easier as we get `const fn` constructors for locks in the future.