RS.CLIPPY.IGNORED_UNIT_PATTERNS

Suggest replacing `_` by `()` in patterns where appropriate

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

What it does

Checks for usage of _ in patterns of type ().

Why is this bad?

Matching with () explicitly instead of _ outlines the fact that the pattern contains no data. Also it would detect a type change that _ would ignore.

Example

match std::fs::create_dir("tmp-work-dir") {
    Ok(_) => println!("Working directory created"),
    Err(s) => eprintln!("Could not create directory: {s}"),
}

Use instead:

match std::fs::create_dir("tmp-work-dir") {
    Ok(()) => println!("Working directory created"),
    Err(s) => eprintln!("Could not create directory: {s}"),
}