src/tools/clippy/tests/ui/by_ref_peekable_peek.3.fixed

#![warn(clippy::by_ref_peekable_peek)]

struct S;

impl S {
    fn by_ref(&mut self) -> impl Iterator<Item = i32> {
        std::iter::empty()
    }
}

macro_rules! mac {
    ($x:expr) => {
        $x.by_ref().peekable().peek()
    };
}

fn with_non_clone_parameter(i: &mut impl Iterator<Item = i32>) {
    // This won't suggest `.clone().next().as_ref()` as `i` is not `Clone`
    let _: Option<&i32> = i.next().as_ref();
    //~^ by_ref_peekable_peek
}

fn with_cloneable_local_iterator(a: Vec<i32>) {
    let mut i = a.into_iter().peekable();
    let _: Option<&i32> = i.peek();
    //~^ by_ref_peekable_peek
}

fn with_cloneable_local_iterator_from_macro() {
    macro_rules! mac {
        () => {
            [1, 2, 3].into_iter()
        };
    }
    let mut i = mac!().peekable();
    let _: Option<&i32> = i.peek();
    //~^ by_ref_peekable_peek
}

fn main() {
    let mut iter = [1, 2, 3].into_iter().peekable();
    let _: Option<&i32> = iter.peek();
    //~^ by_ref_peekable_peek
    #[expect(clippy::needless_borrow)]
    #[allow(clippy::unnecessary_mut_passed)] // For the `.clone().next().as_ref()` suggestion
    let _: Option<&i32> = (&mut iter).clone().next().as_ref();
    //~^ by_ref_peekable_peek

    // Do not lint if `by_ref()` is not the one on `Iterator`
    let _: Option<&i32> = S.by_ref().peekable().peek();

    // Do not lint if coming from a macro, as we cannot ensure
    // that all uses of `.by_ref()` will be `Iterator::by_ref()`.
    let _: Option<&i32> = mac!(iter);
}