Goto in Rust. For tail call optimization

[scottmcm]

@ZiCog

rather optimize it with just loop back to the beginning.

It's not obvious to me that a goto is better here than just using a loop.

Also, in rust you can just use a combinator for tail recursion:

When will Rust have TCO/TCE?

This won't help for general tail calls, but if you can just use tail recursion, you can use a combinator: pub fn factorial(x: usize) -> usize { tail_recurse((x, 1), |(a, b)| { if a == 0 { RecursionResult::Return(b) } else { RecursionResult::Continue((a - 1, a * b)) } }) } Amusingly, that actually generates better code than (1..=x).product()

(Though I do hope one day we get become for explicit tail calls.)