tests/ui/manual_flatten.fixed

#![warn(clippy::manual_flatten)]
#![allow(clippy::useless_vec, clippy::uninlined_format_args)]

fn main() {
    // Test for loop over implicitly adjusted `Iterator` with `if let` expression
    let x = vec![Some(1), Some(2), Some(3)];
    for y in x.into_iter().flatten() {
        println!("{}", y);
    }

    // Test for loop over implicitly adjusted `Iterator` with `if let` statement
    let y: Vec<Result<i32, i32>> = vec![];
    for n in y.clone().into_iter().flatten() {
        println!("{}", n);
    }

    // Test for loop over by reference
    for n in y.iter().flatten() {
        println!("{}", n);
    }

    // Test for loop over an implicit reference
    let z = &y;
    for n in z.iter().flatten() {
        println!("{}", n);
    }

    // Test for loop over `Iterator` with `if let` expression
    let z = vec![Some(1), Some(2), Some(3)];
    let z = z.iter();
    for m in z.flatten() {
        println!("{}", m);
    }

    // Using the `None` variant should not trigger the lint
    // Note: for an autofixable suggestion, the binding in the for loop has to take the
    // name of the binding in the `if let`
    let z = vec![Some(1), Some(2), Some(3)];
    for n in z {
        if n.is_none() {
            println!("Nada.");
        }
    }

    // Using the `Err` variant should not trigger the lint
    for n in y.clone() {
        if let Err(e) = n {
            println!("Oops: {}!", e);
        }
    }

    // Having an else clause should not trigger the lint
    for n in y.clone() {
        if let Ok(n) = n {
            println!("{}", n);
        } else {
            println!("Oops!");
        }
    }

    let vec_of_ref = vec![&Some(1)];
    for n in vec_of_ref.iter().copied().flatten() {
        println!("{:?}", n);
    }

    let vec_of_ref = &vec_of_ref;
    for n in vec_of_ref.iter().copied().flatten() {
        println!("{:?}", n);
    }

    let slice_of_ref = &[&Some(1)];
    for n in slice_of_ref.iter().copied().flatten() {
        println!("{:?}", n);
    }

    struct Test {
        a: usize,
    }

    let mut vec_of_struct = [Some(Test { a: 1 }), None];

    // Usage of `if let` expression should not trigger lint
    for n in vec_of_struct.iter_mut() {
        if let Some(z) = n {
            *n = None;
        }
    }

    // Using manual flatten should not trigger the lint
    for n in vec![Some(1), Some(2), Some(3)].iter().flatten() {
        println!("{}", n);
    }

    // Using nested `Some` pattern should not trigger the lint
    for n in vec![Some((1, Some(2)))] {
        if let Some((_, Some(n))) = n {
            println!("{}", n);
        }
    }

    macro_rules! inner {
        ($id:ident / $new:pat => $action:expr) => {
            if let Some($new) = $id {
                $action;
            }
        };
    }

    // Usage of `if let` expression with macro should not trigger lint
    for ab in [Some((1, 2)), Some((3, 4))] {
        inner!(ab / (c, d) => println!("{c}-{d}"));
    }

    macro_rules! args {
        ($($arg:expr),*) => {
            vec![$(Some($arg)),*]
        };
    }

    // Usage of `if let` expression with macro should not trigger lint
    for n in args!(1, 2, 3) {
        if let Some(n) = n {
            println!("{:?}", n);
        }
    }

    // This should trigger the lint, but the applicability is `MaybeIncorrect`
    let z = vec![Some(1), Some(2), Some(3)];
    for n in z.into_iter().flatten() {
        println!("{:?}", n);
    }

    run_unformatted_tests();
}

#[rustfmt::skip]
fn run_unformatted_tests() {
    // Skip rustfmt here on purpose so the suggestion does not fit in one line
    for n in vec![
    //~^ manual_flatten

        Some(1),
        Some(2),
        Some(3)
    ].iter().flatten() {
        println!("{:?}", n);
    }
}