mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-27 09:14:20 +00:00
289 lines
11 KiB
Markdown
289 lines
11 KiB
Markdown
# Clippy
|
|
|
|
[/badge.svg?branch=auto&event=push)](https://github.com/rust-lang/rust-clippy/actions?query=workflow%3A%22Clippy+Test+(bors)%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 600 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, suspicious, style, complexity, perf) | **warn/deny** |
|
|
| `clippy::correctness` | code that is outright wrong or useless | **deny** |
|
|
| `clippy::suspicious` | code that is most likely wrong or useless | **warn** |
|
|
| `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 have occasional false positives | allow |
|
|
| `clippy::restriction` | lints which prevent the use of language and library features[^restrict] | 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 `restriction` category should, *emphatically*, not be enabled as a whole. The contained
|
|
lints may lint against perfectly reasonable code, may not have an alternative suggestion,
|
|
and may contradict any other lints (including other categories). Lints should be considered
|
|
on a case-by-case basis before enabling.
|
|
|
|
[^restrict]: Some use cases for `restriction` lints include:
|
|
- Strict coding styles (e.g. [`clippy::else_if_without_else`]).
|
|
- Additional restrictions on CI (e.g. [`clippy::todo`]).
|
|
- Preventing panicking in certain functions (e.g. [`clippy::unwrap_used`]).
|
|
- Running a lint only on a subset of code (e.g. `#[forbid(clippy::float_arithmetic)]` on a module).
|
|
|
|
[`clippy::else_if_without_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#else_if_without_else
|
|
[`clippy::todo`]: https://rust-lang.github.io/rust-clippy/master/index.html#todo
|
|
[`clippy::unwrap_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_used
|
|
|
|
---
|
|
|
|
Table of contents:
|
|
|
|
* [Usage instructions](#usage)
|
|
* [Configuration](#configuration)
|
|
* [Contributing](#contributing)
|
|
* [License](#license)
|
|
|
|
## Usage
|
|
|
|
Below are instructions on how to use Clippy as a cargo subcommand,
|
|
in projects that do not use cargo, 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, just like the compiler.
|
|
|
|
```terminal
|
|
cargo clippy --fix
|
|
```
|
|
|
|
#### 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
|
|
```
|
|
|
|
### Using `clippy-driver`
|
|
|
|
Clippy can also be used in projects that do not use cargo. To do so, run `clippy-driver`
|
|
with the same arguments you use for `rustc`. For example:
|
|
|
|
```terminal
|
|
clippy-driver --edition 2018 -Cpanic=abort foo.rs
|
|
```
|
|
|
|
Note that `clippy-driver` is designed for running Clippy only and should not be used as a general
|
|
replacement for `rustc`. `clippy-driver` may produce artifacts that are not optimized as expected,
|
|
for example.
|
|
|
|
### Travis CI
|
|
|
|
You can add Clippy to Travis CI in the same way you use it locally:
|
|
|
|
```yaml
|
|
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
|
|
|
|
### 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)]`).
|
|
Note that `rustc` has additional [lint groups](https://doc.rust-lang.org/rustc/lints/groups.html).
|
|
|
|
* 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::...
|
|
```
|
|
|
|
### Configure the behavior of some lints
|
|
|
|
Some lints can be configured in a TOML file named `clippy.toml` or `.clippy.toml`. It contains a basic `variable =
|
|
value` mapping e.g.
|
|
|
|
```toml
|
|
avoid-breaking-exported-api = false
|
|
disallowed-names = ["toto", "tata", "titi"]
|
|
```
|
|
|
|
The [table of configurations](https://doc.rust-lang.org/nightly/clippy/lint_configuration.html)
|
|
contains all config values, their default, and a list of lints they affect.
|
|
Each [configurable lint](https://rust-lang.github.io/rust-clippy/master/index.html#Configuration)
|
|
, also contains information about these values.
|
|
|
|
For configurations that are a list type with default values such as
|
|
[disallowed-names](https://rust-lang.github.io/rust-clippy/master/index.html#disallowed_names),
|
|
you can use the unique value `".."` to extend the default values instead of replacing them.
|
|
|
|
```toml
|
|
# default of disallowed-names is ["foo", "baz", "quux"]
|
|
disallowed-names = ["bar", ".."] # -> ["bar", "foo", "baz", "quux"]
|
|
```
|
|
|
|
> **Note**
|
|
>
|
|
> `clippy.toml` or `.clippy.toml` cannot be used to allow/deny lints.
|
|
|
|
To deactivate the “for further information visit *lint-link*” message you can
|
|
define the `CLIPPY_DISABLE_DOCS_LINKS` environment variable.
|
|
|
|
### 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"
|
|
```
|
|
|
|
Alternatively, the [`rust-version` field](https://doc.rust-lang.org/cargo/reference/manifest.html#the-rust-version-field)
|
|
in the `Cargo.toml` can be used.
|
|
|
|
```toml
|
|
# Cargo.toml
|
|
rust-version = "1.30"
|
|
```
|
|
|
|
The MSRV can also be specified as an attribute, like below.
|
|
|
|
```rust,ignore
|
|
#![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
|
|
|
|
<!-- REUSE-IgnoreStart -->
|
|
|
|
Copyright 2014-2022 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.
|
|
|
|
<!-- REUSE-IgnoreEnd -->
|