Function chaining_impl

pub(in ::slice::cmp) const fn chaining_impl<'l, 'r, A: PartialOrd, B, C>(left: &'l [A], right: &'r [A], elem_chain: impl ~const Fn(&'l A, &'r A) -> ControlFlow<B>, len_chain: impl ~const for<'a> FnOnce(&'a usize, &'a usize) -> ControlFlow<B, C>) -> ControlFlow<B, C>