Possible to cause infinite loop?

[andrews05]

I was just looking at the latest properties for Options and it seems it could infinite loop if both iteration_count and iterations_without_improvement are None. Sure, you would be silly to deliberately set them both to None, but I'm concerned it could quite easily happen unintentionally if you did something like this:

Options {
    iteration_count: NonZeroU64::new(get_value_from_args()),
    ..Default::default()
}

If get_value_from_args() returned 0 then you might have a problem.

Previously iteration_count wasn't an option so you were required to unwrap the NonZero. I think it was safer like this - you could always set it to NonZeroU64::MAX if you wanted to rely solely on iterations_without_improvement.

[Alejandro González]

I think your analysis of the situation is spot on. Client code resorting to NonZeroU64::new with variable input can be a footgun I didn't realize when this feature was merged, and while such a mistake would be on the user's end, the fact that it is easy for client code to make this mistake suggests that a better API could help.

Dropping the Option here is a good way to go. For practical purposes, there is no difference between 2⁶⁴ - 1 iterations and potentially infinite iterations. In fact, I think it'd be good to drop the Option from both, so it is not possible to do too few iterations without improvement if a NonZero is constructed from a zero iterations_without_improvement number.