rust/tests/ui/iter_count.rs

// run-rustfix
// aux-build:option_helpers.rs

#![warn(clippy::iter_count)]
#![allow(
    unused_variables,
    array_into_iter,
    unused_mut,
    clippy::into_iter_on_ref,
    clippy::unnecessary_operation
)]

extern crate option_helpers;

use option_helpers::IteratorFalsePositives;
use std::collections::{HashSet, VecDeque};

/// Struct to generate false positives for things with `.iter()`.
#[derive(Copy, Clone)]
struct HasIter;

impl HasIter {
    fn iter(self) -> IteratorFalsePositives {
        IteratorFalsePositives { foo: 0 }
    }

    fn iter_mut(self) -> IteratorFalsePositives {
        IteratorFalsePositives { foo: 0 }
    }

    fn into_iter(self) -> IteratorFalsePositives {
        IteratorFalsePositives { foo: 0 }
    }
}

fn main() {
    let mut vec = vec![0, 1, 2, 3];
    let mut boxed_slice: Box<[u8]> = Box::new([0, 1, 2, 3]);
    let mut vec_deque: VecDeque<_> = vec.iter().cloned().collect();
    let mut hash_set = HashSet::new();
    hash_set.insert(1);

    &vec[..].iter().count();
    vec.iter().count();
    boxed_slice.iter().count();
    vec_deque.iter().count();
    hash_set.iter().count();

    vec.iter_mut().count();
    &vec[..].iter_mut().count();
    vec_deque.iter_mut().count();

    &vec[..].into_iter().count();
    vec.into_iter().count();
    vec_deque.into_iter().count();

    // Make sure we don't lint for non-relevant types.
    let false_positive = HasIter;
    false_positive.iter().count();
    false_positive.iter_mut().count();
    false_positive.into_iter().count();
}