Rust on BBC micro:bit
This is by now a familiar sight:  #[lang = "eh_personality"] extern fn eh_personality() {}
  #[lang = "panic_fmt"] extern fn panic_fmt() -> ! { loop {} }

But it's a little unsatisfying.What does eh_personality actually do, and how would you write a 'real' implementation?I can guess what panic_fmt is for, but exactly what is it supposed to do, and how would you write a 'real' implementation?