mirror of
https://github.com/rust-lang/rust.git
synced 2024-12-03 20:23:59 +00:00
228 lines
7.1 KiB
Markdown
228 lines
7.1 KiB
Markdown
# rust-clippy
|
|
|
|
[](https://travis-ci.org/rust-lang-nursery/rust-clippy)
|
|
[](https://ci.appveyor.com/project/rust-lang-nursery/rust-clippy)
|
|
[](https://crates.io/crates/clippy)
|
|
[](#license)
|
|
|
|
A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
|
|
|
|
[There are 253 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)
|
|
|
|
We have a bunch of lint categories to allow you to choose how much clippy is supposed to ~~annoy~~ help you:
|
|
|
|
* `clippy` (everything that has no false positives)
|
|
* `clippy_pedantic` (everything)
|
|
* `clippy_nursery` (new lints that aren't quite ready yet)
|
|
* `clippy_style` (code that should be written in a more idiomatic way)
|
|
* `clippy_complexity` (code that does something simple but in a complex way)
|
|
* `clippy_perf` (code that can be written in a faster way)
|
|
* **`clippy_correctness`** (code that is just outright wrong or very very useless)
|
|
|
|
More to come, please [file an issue](https://github.com/rust-lang-nursery/rust-clippy/issues) if you have ideas!
|
|
|
|
Table of contents:
|
|
|
|
* [Usage instructions](#usage)
|
|
* [Configuration](#configuration)
|
|
* [License](#license)
|
|
|
|
## Usage
|
|
|
|
Since this is a tool for helping the developer of a library or application
|
|
write better code, it is recommended not to include clippy as a hard dependency.
|
|
Options include using it as an optional dependency, as a cargo subcommand, or
|
|
as an included feature during build. All of these options are detailed below.
|
|
|
|
As a general rule clippy will only work with the *latest* Rust nightly for now.
|
|
|
|
To install Rust nightly, the recommended way is to use [rustup](https://rustup.rs/):
|
|
|
|
```terminal
|
|
rustup install nightly
|
|
```
|
|
|
|
### As a cargo subcommand (`cargo clippy`)
|
|
|
|
One way to use clippy is by installing clippy through cargo as a cargo
|
|
subcommand.
|
|
|
|
```terminal
|
|
cargo +nightly install clippy
|
|
```
|
|
|
|
(The `+nightly` is not necessary if your default `rustup` install is nightly)
|
|
|
|
Now you can run clippy by invoking `cargo +nightly clippy`.
|
|
|
|
To update the subcommand together with the latest nightly use the [rust-update](rust-update) script or run:
|
|
|
|
```terminal
|
|
rustup update nightly
|
|
cargo +nightly install --force clippy
|
|
```
|
|
|
|
In case you are not using rustup, you need to set the environment flag
|
|
`SYSROOT` during installation so clippy knows where to find `librustc` and
|
|
similar crates.
|
|
|
|
```terminal
|
|
SYSROOT=/path/to/rustc/sysroot cargo install clippy
|
|
```
|
|
|
|
### Optional dependency
|
|
|
|
In some cases you might want to include clippy in your project directly, as an
|
|
optional dependency. To do this, just modify `Cargo.toml`:
|
|
|
|
```toml
|
|
[dependencies]
|
|
clippy = { version = "*", optional = true }
|
|
```
|
|
|
|
And, in your `main.rs` or `lib.rs`, add these lines:
|
|
|
|
```rust
|
|
#![cfg_attr(feature="clippy", feature(plugin))]
|
|
#![cfg_attr(feature="clippy", plugin(clippy))]
|
|
```
|
|
|
|
Then build by enabling the feature: `cargo +nightly build --features "clippy"`.
|
|
|
|
Instead of adding the `cfg_attr` attributes you can also run clippy on demand:
|
|
`cargo rustc --features clippy -- -Z no-trans -Z extra-plugins=clippy`
|
|
(the `-Z no trans`, while not necessary, will stop the compilation process after
|
|
typechecking (and lints) have completed, which can significantly reduce the runtime).
|
|
|
|
Alternatively, to only run clippy when testing:
|
|
|
|
```toml
|
|
[dev-dependencies]
|
|
clippy = { version = "*" }
|
|
```
|
|
|
|
and add to `main.rs` or `lib.rs`:
|
|
|
|
```
|
|
#![cfg_attr(test, feature(plugin))]
|
|
#![cfg_attr(test, plugin(clippy))]
|
|
```
|
|
|
|
### Running clippy from the command line without installing it
|
|
|
|
To have cargo compile your crate with clippy without clippy installation and without needing `#![plugin(clippy)]`
|
|
in your code, you can use:
|
|
|
|
```terminal
|
|
cargo run --bin cargo-clippy --manifest-path=path_to_clippys_Cargo.toml
|
|
```
|
|
|
|
*[Note](https://github.com/rust-lang-nursery/rust-clippy/wiki#a-word-of-warning):*
|
|
Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
|
|
|
|
### As a Compiler Plugin
|
|
|
|
*Note:* This is not a recommended installation method.
|
|
|
|
Since stable Rust is backwards compatible, you should be able to
|
|
compile your stable programs with nightly Rust with clippy plugged in to
|
|
circumvent this.
|
|
|
|
Add in your `Cargo.toml`:
|
|
|
|
```toml
|
|
[dependencies]
|
|
clippy = "*"
|
|
```
|
|
|
|
You then need to add `#![feature(plugin)]` and `#![plugin(clippy)]` to the top
|
|
of your crate entry point (`main.rs` or `lib.rs`).
|
|
|
|
Sample `main.rs`:
|
|
|
|
```rust
|
|
#![feature(plugin)]
|
|
|
|
#![plugin(clippy)]
|
|
|
|
|
|
fn main(){
|
|
let x = Some(1u8);
|
|
match x {
|
|
Some(y) => println!("{:?}", y),
|
|
_ => ()
|
|
}
|
|
}
|
|
```
|
|
|
|
Produces this warning:
|
|
|
|
```terminal
|
|
src/main.rs:8:5: 11:6 warning: you seem to be trying to use match for destructuring a single type. Consider using `if let`, #[warn(single_match)] on by default
|
|
src/main.rs:8 match x {
|
|
src/main.rs:9 Some(y) => println!("{:?}", y),
|
|
src/main.rs:10 _ => ()
|
|
src/main.rs:11 }
|
|
src/main.rs:8:5: 11:6 help: Try
|
|
if let Some(y) = x { println!("{:?}", y) }
|
|
```
|
|
|
|
## Configuration
|
|
|
|
Some lints can be configured in a TOML file named with `clippy.toml` or `.clippy.toml`. It contains basic `variable = value` mapping eg.
|
|
|
|
```toml
|
|
blacklisted-names = ["toto", "tata", "titi"]
|
|
cyclomatic-complexity-threshold = 30
|
|
```
|
|
|
|
See the [list of lints](https://rust-lang-nursery.github.io/rust-clippy/master/index.html) for more information about which lints can be configured and the
|
|
meaning of the variables.
|
|
|
|
You can also specify the path to the configuration file with:
|
|
|
|
```rust
|
|
#![plugin(clippy(conf_file="path/to/clippy's/configuration"))]
|
|
```
|
|
|
|
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 `allow`/`warn`/`deny`:
|
|
|
|
* the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy)]`)
|
|
|
|
* all lints using both the `clippy` and `clippy_pedantic` lint groups (`#![deny(clippy)]`,
|
|
`#![deny(clippy_pedantic)]`). Note that `clippy_pedantic` contains some very aggressive
|
|
lints prone to false positives.
|
|
|
|
* only some lints (`#![deny(single_match, box_vec)]`, etc)
|
|
|
|
* `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
|
|
|
|
Note: `deny` produces errors instead of warnings.
|
|
|
|
For convenience, `cargo clippy` automatically defines a `cargo-clippy`
|
|
feature. This lets you set lint levels and compile with or without clippy
|
|
transparently:
|
|
|
|
```rust
|
|
#[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
|
|
```
|
|
|
|
## Updating rustc
|
|
|
|
Sometimes, rustc moves forward without clippy catching up. Therefore updating
|
|
rustc may leave clippy a non-functional state until we fix the resulting
|
|
breakage.
|
|
|
|
You can use the [rust-update](rust-update) script to update rustc only if
|
|
clippy would also update correctly.
|
|
|
|
## License
|
|
|
|
Licensed under [MPL](https://www.mozilla.org/MPL/2.0/).
|
|
If you're having issues with the license, let me know and I'll try to change it to something more permissive.
|