iter_on_empty_collections.fixed

//@run-rustfix
#![warn(clippy::iter_on_empty_collections)]
#![allow(clippy::iter_next_slice, clippy::redundant_clone)]

fn array() {
    assert_eq!(std::iter::empty().next(), Option::<i32>::None);
    assert_eq!(std::iter::empty().next(), Option::<&mut i32>::None);
    assert_eq!(std::iter::empty().next(), Option::<&i32>::None);
    assert_eq!(std::iter::empty().next(), Option::<i32>::None);
    assert_eq!(std::iter::empty().next(), Option::<&mut i32>::None);
    assert_eq!(std::iter::empty().next(), Option::<&i32>::None);

    let x: [u32; 0] = [];
    x.iter().copied().chain(std::iter::empty());
    x.iter().copied().eq(std::iter::empty());
    x.iter().copied().ne(std::iter::empty());
    let x: Vec<u32> = vec![];
    x.iter().copied().chain(std::iter::empty());
    x.iter().copied().eq(std::iter::empty());
    x.iter().copied().ne(std::iter::empty());

    // Don't trigger on non-iter methods
    let _: Option<String> = None.clone();
    let _: [String; 0] = [].clone();

    // FIXME: See line 135 in `single_or_empty_collections_iter`
    // Don't trigger on match or if branches
    // let _ = match 123 {
    //     123 => [].iter(),
    //     _ => ["test"].iter(),
    // };

    // let _ = if false { ["test"].iter() } else { [].iter() };
}

macro_rules! in_macros {
    () => {
        assert_eq!(std::iter::empty().next(), Option::<i32>::None);
        assert_eq!(std::iter::empty().next(), Option::<&mut i32>::None);
        assert_eq!(std::iter::empty().next(), Option::<&i32>::None);
        assert_eq!(std::iter::empty().next(), Option::<i32>::None);
        assert_eq!(std::iter::empty().next(), Option::<&mut i32>::None);
        assert_eq!(std::iter::empty().next(), Option::<&i32>::None);
    };
}

// Don't trigger on a `None` that isn't std's option
mod custom_option {
    #[allow(unused)]
    enum CustomOption {
        Some(i32),
        None,
    }

    impl CustomOption {
        fn iter(&self) {}
        fn iter_mut(&mut self) {}
        fn into_iter(self) {}
    }
    use CustomOption::*;

    pub fn custom_option() {
        None.iter();
        None.iter_mut();
        None.into_iter();
    }
}

fn main() {
    array();
    custom_option::custom_option();
    in_macros!();
}