RS.CLIPPY.DOUBLE_MUST_USE

`#[must_use]` attribute on a `#[must_use]`-returning function / method

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

What it does

Checks for a #[must_use] attribute without further information on functions and methods that return a type already marked as #[must_use].

Why is this bad?

The attribute isn't needed. Not using the result will already be reported. Alternatively, one can add some text to the attribute to improve the lint message.

Examples

#[must_use]
fn double_must_use() -> Result<(), ()> {
    unimplemented!();
}