Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::deprecated_cfg_attr: `cfg_attr` is deprecated for rustfmt and got replaced by tool attributes

What it meansChecks for #[cfg_attr(rustfmt, rustfmt_skip)] and suggests to replace it with #[rustfmt::skip]. It is in the complexity group and warns by default.

What you see

warning: `cfg_attr` is deprecated for rustfmt and got replaced by tool attributes
 --> main.rs:1:1
  |
1 | #[cfg_attr(rustfmt, rustfmt_skip)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `#[rustfmt::skip]`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#deprecated_cfg_attr
  = note: `#[warn(clippy::deprecated_cfg_attr)]` 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?

Since tool_attributes (rust-lang/rust#44690) are stable now, they should be used instead of the old cfg_attr(rustfmt) attributes.

Code that does something simple in a complicated way. Warns by default.

How to fix it

Clippy can fix this one for you: run cargo clippy --fix (add --allow-dirty if you have uncommitted changes). Review the diff before you commit.

Flagged

#[cfg_attr(rustfmt, rustfmt_skip)]
fn main() { }

Write this instead

#[rustfmt::skip]
fn main() { }

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
deprecated_cfg_attr = "allow"

One run

cargo clippy -- -A clippy::deprecated-cfg-attr

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.

Settings in clippy.toml

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

Complexitygroup

warndefault level

yesfixed by cargo clippy --fix

1.32.0added in Rust

Clippy's own documentation

What it does

Checks for #[cfg_attr(rustfmt, rustfmt_skip)] and suggests to replace it with #[rustfmt::skip].

Why is this bad?

Since tool_attributes (rust-lang/rust#44690) are stable now, they should be used instead of the old cfg_attr(rustfmt) attributes.

Known problems

This lint doesn’t detect crate level inner attributes, because they get processed before the PreExpansionPass lints get executed. See #3123

Example

#[cfg_attr(rustfmt, rustfmt_skip)]
fn main() { }

Use instead:

#[rustfmt::skip]
fn main() { }

Configuration

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

(default: current version)

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

Up next

Also worth your time

Did this answer your question?