RS.CLIPPY.TYPE_COMPLEXITY

Usage of very complex types that might be better factored into `type` definitions

This checker is a Clippy lint created by The Rust Project Contributors. The documentation shown here is a copy of the original documentation for: type_complexity. Copyright ©2025 The Rust Team. All rights reserved.

What it does

Checks for types used in structs, parameters and let declarations above a certain complexity threshold.

Why is this bad?

Too complex types make the code less readable. Consider using a type definition to simplify them.

Example

struct PointMatrixContainer {
    matrix: Rc<Vec<Vec<Box<(u32, u32, u32, u32)>>>>,
}

fn main() {
    let point_matrix: Vec<Vec<Box<(u32, u32, u32, u32)>>> = vec![
        vec![
            Box::new((1, 2, 3, 4)),
            Box::new((5, 6, 7, 8)),
        ],
        vec![
            Box::new((9, 10, 11, 12)),
        ],
    ];

    let shared_point_matrix: Rc<Vec<Vec<Box<(u32, u32, u32, u32)>>>> = Rc::new(point_matrix);

    let container = PointMatrixContainer {
        matrix: shared_point_matrix,
    };

    // ...
}

Use instead:

Example

type PointMatrix = Vec<Vec<Box<(u32, u32, u32, u32)>>>;
type SharedPointMatrix = Rc<PointMatrix>;

struct PointMatrixContainer {
    matrix: SharedPointMatrix,
}

fn main() {
    let point_matrix: PointMatrix = vec![
        vec![
            Box::new((1, 2, 3, 4)),
            Box::new((5, 6, 7, 8)),
        ],
        vec![
            Box::new((9, 10, 11, 12)),
        ],
    ];

    let shared_point_matrix: SharedPointMatrix = Rc::new(point_matrix);

    let container = PointMatrixContainer {
        matrix: shared_point_matrix,
    };

    // ...
}

Configuration

type-complexity-threshold: The maximum complexity a type can have

(default: 250)