mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-11-19 11:18:19 +00:00
229 lines
8.4 KiB
Markdown
229 lines
8.4 KiB
Markdown
# Clippy
|
|
|
|
[](https://github.com/rust-lang/rust-clippy/actions?query=workflow%3A%22Clippy+Test%22+event%3Apush+branch%3Aauto)
|
|
[](#license)
|
|
|
|
A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
|
|
|
|
[There are over 400 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
|
|
|
|
Lints are divided into categories, each with a default [lint level](https://doc.rust-lang.org/rustc/lints/levels.html).
|
|
You can choose how much Clippy is supposed to ~~annoy~~ help you by changing the lint level by category.
|
|
|
|
| Category | Description | Default level |
|
|
| --------------------- | ----------------------------------------------------------------------- | ------------- |
|
|
| `clippy::all` | all lints that are on by default (correctness, style, complexity, perf) | **warn/deny** |
|
|
| `clippy::correctness` | code that is outright wrong or very useless | **deny** |
|
|
| `clippy::style` | code that should be written in a more idiomatic way | **warn** |
|
|
| `clippy::complexity` | code that does something simple but in a complex way | **warn** |
|
|
| `clippy::perf` | code that can be written to run faster | **warn** |
|
|
| `clippy::pedantic` | lints which are rather strict or might have false positives | allow |
|
|
| `clippy::nursery` | new lints that are still under development | allow |
|
|
| `clippy::cargo` | lints for the cargo manifest | allow |
|
|
|
|
More to come, please [file an issue](https://github.com/rust-lang/rust-clippy/issues) if you have ideas!
|
|
|
|
The [lint list](https://rust-lang.github.io/rust-clippy/master/index.html) also contains "restriction lints", which are
|
|
for things which are usually not considered "bad", but may be useful to turn on in specific cases. These should be used
|
|
very selectively, if at all.
|
|
|
|
Table of contents:
|
|
|
|
* [Usage instructions](#usage)
|
|
* [Configuration](#configuration)
|
|
* [Contributing](#contributing)
|
|
* [License](#license)
|
|
|
|
## Usage
|
|
|
|
Below are instructions on how to use Clippy as a subcommand, compiled from source
|
|
or in Travis CI.
|
|
|
|
### As a cargo subcommand (`cargo clippy`)
|
|
|
|
One way to use Clippy is by installing Clippy through rustup as a cargo
|
|
subcommand.
|
|
|
|
#### Step 1: Install rustup
|
|
|
|
You can install [rustup](https://rustup.rs/) on supported platforms. This will help
|
|
us install Clippy and its dependencies.
|
|
|
|
If you already have rustup installed, update to ensure you have the latest
|
|
rustup and compiler:
|
|
|
|
```terminal
|
|
rustup update
|
|
```
|
|
|
|
#### Step 2: Install Clippy
|
|
|
|
Once you have rustup and the latest stable release (at least Rust 1.29) installed, run the following command:
|
|
|
|
```terminal
|
|
rustup component add clippy
|
|
```
|
|
If it says that it can't find the `clippy` component, please run `rustup self update`.
|
|
|
|
#### Step 3: Run Clippy
|
|
|
|
Now you can run Clippy by invoking the following command:
|
|
|
|
```terminal
|
|
cargo clippy
|
|
```
|
|
|
|
#### Automatically applying Clippy suggestions
|
|
|
|
Clippy can automatically apply some lint suggestions.
|
|
Note that this is still experimental and only supported on the nightly channel:
|
|
|
|
```terminal
|
|
cargo clippy --fix -Z unstable-options
|
|
```
|
|
|
|
#### Workspaces
|
|
|
|
All the usual workspace options should work with Clippy. For example the following command
|
|
will run Clippy on the `example` crate:
|
|
|
|
```terminal
|
|
cargo clippy -p example
|
|
```
|
|
|
|
As with `cargo check`, this includes dependencies that are members of the workspace, like path dependencies.
|
|
If you want to run Clippy **only** on the given crate, use the `--no-deps` option like this:
|
|
|
|
```terminal
|
|
cargo clippy -p example -- --no-deps
|
|
```
|
|
|
|
### Travis CI
|
|
|
|
You can add Clippy to Travis CI in the same way you use it locally:
|
|
|
|
```yml
|
|
language: rust
|
|
rust:
|
|
- stable
|
|
- beta
|
|
before_script:
|
|
- rustup component add clippy
|
|
script:
|
|
- cargo clippy
|
|
# if you want the build job to fail when encountering warnings, use
|
|
- cargo clippy -- -D warnings
|
|
# in order to also check tests and non-default crate features, use
|
|
- cargo clippy --all-targets --all-features -- -D warnings
|
|
- cargo test
|
|
# etc.
|
|
```
|
|
|
|
Note that adding `-D warnings` will cause your build to fail if **any** warnings are found in your code.
|
|
That includes warnings found by rustc (e.g. `dead_code`, etc.). If you want to avoid this and only cause
|
|
an error for Clippy warnings, use `#![deny(clippy::all)]` in your code or `-D clippy::all` on the command
|
|
line. (You can swap `clippy::all` with the specific lint category you are targeting.)
|
|
|
|
## Configuration
|
|
|
|
Some lints can be configured in a TOML file named `clippy.toml` or `.clippy.toml`. It contains a basic `variable =
|
|
value` mapping eg.
|
|
|
|
```toml
|
|
blacklisted-names = ["toto", "tata", "titi"]
|
|
cognitive-complexity-threshold = 30
|
|
```
|
|
|
|
See the [list of lints](https://rust-lang.github.io/rust-clippy/master/index.html) for more information about which
|
|
lints can be configured and the meaning of the variables.
|
|
|
|
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
|
|
|
|
```terminal
|
|
cargo clippy -- -A clippy::lint_name
|
|
```
|
|
|
|
And to warn on `lint_name`, run
|
|
|
|
```terminal
|
|
cargo clippy -- -W clippy::lint_name
|
|
```
|
|
|
|
This also works with lint groups. For example you
|
|
can run Clippy with warnings for all lints enabled:
|
|
```terminal
|
|
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:
|
|
```terminal
|
|
cargo clippy -- -A clippy::all -W clippy::useless_format -W clippy::...
|
|
```
|
|
Note that if you've run clippy before, this may only take effect after you've modified a file or ran `cargo clean`.
|
|
|
|
### 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.
|
|
|
|
```toml
|
|
msrv = "1.30.0"
|
|
```
|
|
|
|
The MSRV can also be specified as an inner attribute, like below.
|
|
|
|
```rust
|
|
#![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](https://rust-lang.github.io/rust-clippy/master/index.html#msrv)
|
|
|
|
## Contributing
|
|
|
|
If you want to contribute to Clippy, you can find more information in [CONTRIBUTING.md](https://github.com/rust-lang/rust-clippy/blob/master/CONTRIBUTING.md).
|
|
|
|
## License
|
|
|
|
Copyright 2014-2020 The Rust Project Developers
|
|
|
|
Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
|
|
[https://www.apache.org/licenses/LICENSE-2.0](https://www.apache.org/licenses/LICENSE-2.0)> or the MIT license
|
|
<LICENSE-MIT or [https://opensource.org/licenses/MIT](https://opensource.org/licenses/MIT)>, at your
|
|
option. Files in the project may not be
|
|
copied, modified, or distributed except according to those terms.
|