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, which is searched for in:

The directory specified by the CLIPPY_CONF_DIR environment variable, or
The directory specified by the CARGO_MANIFEST_DIR environment variable, or
The current directory.

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

Attributes in Code

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

the whole set of warn-by-default lints using the clippy lint group (#![allow(clippy::all)])
all lints using both the clippy and clippy::pedantic lint groups (#![warn(clippy::all, 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 most useful in scripts used in CI/CD.

Command Line Flags

If you do not want to include your lint levels in the 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 pedantic lints enabled:

cargo clippy -- -W clippy::pedantic

If you care only about a certain lints, you can allow all others and then explicitly warn on the lints you are interested in:

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

Lints Section in `Cargo.toml`

Finally, lints can be allowed/denied using the lints section) in the Cargo.toml file:

To deny clippy::enum_glob_use, put the following in the Cargo.toml:

[lints.clippy]
enum_glob_use = "deny"

For more details and options, refer to the Cargo documentation.

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 clippy cfg is not set. You may need to provide a stub so that the code compiles:

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

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

Clippy Documentation