MAP_UNIT_FN in rustc_lint::map_unit_fn - Rust
Description: The `map_unit_fn` lint checks for `Iterator::map` receive a callable that returns `()`.

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## MAP_UNIT_FN

# Static MAP_UNIT_FN

Source

    pub static MAP_UNIT_FN: &Lint

Expand description

The `map_unit_fn` lint checks for `Iterator::map` receive a callable that returns `()`.

#### §Example

    fn foo(items: &mut Vec<u8>) {
        items.sort();
    }

    fn main() {
        let mut x: Vec<Vec<u8>> = vec![
            vec![0, 2, 1],
            vec![5, 4, 3],
        ];
        x.iter_mut().map(foo);
    }

{{produces}}

#### §Explanation

Mapping to `()` is almost always a mistake.