Clippy lint · Suspicious · checked with Clippy 0.1.99

clippy::duplicated_attributes: duplicated attribute

What it meansChecks for attributes that appear two or more times. It is in the suspicious group and warns by default.

What you see

warning: duplicated attribute
 --> main.rs:4:9
  |
4 | #[allow(dead_code)]
  |         ^^^^^^^^^
  |
note: first defined here
 --> main.rs:3:9
  |
3 | #[allow(dead_code)]
  |         ^^^^^^^^^
help: remove this attribute
 --> main.rs:4:9
  |
4 | #[allow(dead_code)]
  |         ^^^^^^^^^
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#duplicated_attributes
  = note: `#[warn(clippy::duplicated_attributes)]` on by default

Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.

Does it matter?

Repeating an attribute on the same item (or globally on the same crate) is unnecessary and doesn’t have an effect.

Code that is most likely wrong or useless. Warns by default.

How to fix it

Clippy does not fix this one automatically. Change the code by hand:

Flagged

#[allow(dead_code)]
#[allow(dead_code)]
fn foo() {}

Write this instead

#[allow(dead_code)]
fn foo() {}

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

On one item

#[allow(clippy::duplicated_attributes)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
duplicated_attributes = "allow"

One run

cargo clippy -- -A clippy::duplicated-attributes

The [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.

Suspiciousgroup

warndefault level

nofixed by cargo clippy --fix

1.79.0added in Rust

Clippy's own documentation

What it does

Checks for attributes that appear two or more times.

Why is this bad?

Repeating an attribute on the same item (or globally on the same crate) is unnecessary and doesn’t have an effect.

Example

#[allow(dead_code)]
#[allow(dead_code)]
fn foo() {}

Use instead:

#[allow(dead_code)]
fn foo() {}

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

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