Configuration - Clippy Documentation

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# 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:

1. The directory specified by the `CLIPPY_CONF_DIR` environment variable, or
2. The directory specified by the CARGO_MANIFEST_DIR environment variable, or
3. 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
    }
    }