Prefer std::iter::empty() to std::iter::Empty::default()

[adamchalmers]

What it does

Replace std::iter::Empty::default() with std::iter::empty().

These two are equivalent, but one should be preferred: iter::empty requires learning less of the API than iter::Empty::default and it's also simpler.

I actually made this mistake consistently in a PR, it seems silly, but it happens! I caught this during code review and thought, hey, clippy should be able to detect that.

Lint Name

iter-empty-not-iter-empty-default

Category

style

Advantage

• It's shorter
• Rust generally discourages you from knowing the concrete type of an iterator combinator, e.g. you shouldn't really need to know Map or Empty, instead you should just call the map() and empty() functions. If you need to name the output type you should use impl Iterator instead.

Drawbacks

No response

Example

let x = std::iter::Empty::default();

Could be written as:

let x = std::iter::empty();

[kyoto7250]

@rustbot claim