RS.CLIPPY.USED_UNDERSCORE_ITEMS

Using a item which is prefixed with an underscore

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

What it does

Checks for the use of item with a single leading underscore.

Why is this bad?

A single leading underscore is usually used to indicate that a item will not be used. Using such a item breaks this expectation.

Example

fn _foo() {}

struct _FooStruct {}

fn main() {
    _foo();
    let _ = _FooStruct{};
}

Use instead:

fn foo() {}

struct FooStruct {}

fn main() {
    foo();
    let _ = FooStruct{};
}