Configuring Clippy

Note: The configuration file is unstable and may be deprecated in the future.

Some lints can be configured in a TOML file named clippy.toml or .clippy.toml. It contains a basic variable = value mapping e.g.

avoid-breaking-exported-api = false
disallowed-names = ["toto", "tata", "titi"]

The table of configurations contains all config values, their default, and a list of lints they affect. Each configurable lint , also contains information about these values.

For configurations that are a list type with default values such as disallowed-names, you can use the unique value ".." to extend the default values instead of replacing them.

# default of disallowed-names is ["foo", "baz", "quux"]
disallowed-names = ["bar", ".."] # -> ["bar", "foo", "baz", "quux"]

To deactivate the "for further information visit lint-link" message you can define the CLIPPY_DISABLE_DOCS_LINKS environment variable.

Allowing/denying lints

You can add options to your code to allow/warn/deny Clippy lints:

  • the whole set of Warn lints using the clippy lint group (#![deny(clippy::all)])

  • all lints using both the clippy and clippy::pedantic lint groups (#![deny(clippy::all)], #![deny(clippy::pedantic)]). Note that clippy::pedantic contains some very aggressive lints prone to false positives.

  • only some lints (#![deny(clippy::single_match, clippy::box_vec)], etc.)

  • allow/warn/deny can be limited to a single function or module using #[allow(...)], etc.

Note: allow means to suppress the lint for your code. With warn the lint will only emit a warning, while with deny the lint will emit an error, when triggering for your code. An error causes clippy to exit with an error code, so is useful in scripts like CI/CD.

If you do not want to include your lint levels in your code, you can globally enable/disable lints by passing extra flags to Clippy during the run:

To allow lint_name, run

cargo clippy -- -A clippy::lint_name

And to warn on lint_name, run

cargo clippy -- -W clippy::lint_name

This also works with lint groups. For example, you can run Clippy with warnings for all lints enabled:

cargo clippy -- -W clippy::pedantic

If you care only about a single lint, you can allow all others and then explicitly warn on the lint(s) you are interested in:

cargo clippy -- -A clippy::all -W clippy::useless_format -W clippy::...

Specifying the minimum supported Rust version

Projects that intend to support old versions of Rust can disable lints pertaining to newer features by specifying the minimum supported Rust version (MSRV) in the clippy configuration file.

msrv = "1.30.0"

The MSRV can also be specified as an attribute, like below.

#![feature(custom_inner_attributes)]
#![clippy::msrv = "1.30.0"]

fn main() {
    ...
}

You can also omit the patch version when specifying the MSRV, so msrv = 1.30 is equivalent to msrv = 1.30.0.

Note: custom_inner_attributes is an unstable feature, so it has to be enabled explicitly.

Lints that recognize this configuration option can be found here

Disabling evaluation of certain code

Note: This should only be used in cases where other solutions, like #[allow(clippy::all)], are not sufficient.

Very rarely, you may wish to prevent Clippy from evaluating certain sections of code entirely. You can do this with conditional compilation by checking that the cargo-clippy feature is not set. You may need to provide a stub so that the code compiles:

#![allow(unused)]
fn main() {
#[cfg(not(feature = "cargo-clippy"))]
include!(concat!(env!("OUT_DIR"), "/my_big_function-generated.rs"));

#[cfg(feature = "cargo-clippy")]
fn my_big_function(_input: &str) -> Option<MyStruct> {
    None
}
}

This feature is not actually part of your crate, so specifying --all-features to other tools, e.g. cargo test --all-features, will not disable it.