Comment by jeroenhd

Explicit tail call optimization is in the works but I don't think it's available in stable jut yet.

The `become` keyword has already been reserved and work continues to happen (https://github.com/rust-lang/rust/issues/112788). If you enable #![feature(explicit_tail_calls)] you can already use the feature in the nightly compiler: https://play.rust-lang.org/?version=nightly&mode=debug&editi...

(Note that enabling release mode on that link will have the compiler pre-calculate the result so you need to put it to debug mode if you want to see the assembly this generates)