A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
-[There are 357 lints included in this crate!](https://rust-lang.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::all` (everything that is on by default: all the categories below except for `nursery`, `pedantic`, and `cargo`)
-* `clippy::correctness` (code that is just **outright wrong** or **very very useless**, causes hard errors by default)
-* `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::pedantic` (lints which are rather strict, off by default)
-* `clippy::nursery` (new lints that aren't quite ready yet, off by default)
-* `clippy::cargo` (checks against the cargo manifest, off by default)
+[There are over 450 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 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!
-Only the following of those categories are enabled by default:
-
-* `clippy::style`
-* `clippy::correctness`
-* `clippy::complexity`
-* `clippy::perf`
-
-Other categories need to be enabled in order for their lints to be executed.
-
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.
## 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. These options are detailed below.
+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
+#### Step 1: Install Rustup
-You can install [rustup](https://rustup.rs/) on supported platforms. This will help
+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:
+If you already have Rustup installed, update to ensure you have the latest
+Rustup and compiler:
```terminal
rustup update
#### Automatically applying Clippy suggestions
-Some Clippy lint suggestions can be automatically applied by `cargo fix`.
-Note that this is still experimental and only supported on the nightly channel:
+Clippy can automatically apply some lint suggestions, just like the compiler.
```terminal
-cargo fix -Z unstable-options --clippy
+cargo clippy --fix
```
-### Running Clippy from the command line without installing it
+#### Workspaces
-To have cargo compile your crate with Clippy without Clippy installation
-in your code, you can use:
+All the usual workspace options should work with Clippy. For example the following command
+will run Clippy on the `example` crate:
```terminal
-cargo run --bin cargo-clippy --manifest-path=path_to_clippys_Cargo.toml
+cargo clippy -p example
```
-*Note:* Be sure that Clippy was compiled with the same version of rustc that cargo invokes here!
+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
+```
+
+### As a rustc replacement (`clippy-driver`)
+
+Clippy can also be used in projects that do not use cargo. To do so, you will need to replace
+your `rustc` compilation commands with `clippy-driver`. For example, if your project runs:
+
+```terminal
+rustc --edition 2018 -Cpanic=abort foo.rs
+```
+
+Then, to enable Clippy, you will need to call:
+
+```terminal
+clippy-driver --edition 2018 -Cpanic=abort foo.rs
+```
+
+Note that `rustc` will still run, i.e. it will still emit the output files it normally does.
### Travis CI
# etc.
```
-If you are on nightly, It might happen that Clippy is not available for a certain nightly release.
-In this case you can try to conditionally install Clippy from the Git repo.
-
-```yaml
-language: rust
-rust:
- - nightly
-before_script:
- - rustup component add clippy --toolchain=nightly || cargo install --git https://github.com/rust-lang/rust-clippy/ --force clippy
- # 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
value` mapping eg.
```toml
+avoid-breaking-exported-api = false
blacklisted-names = ["toto", "tata", "titi"]
cognitive-complexity-threshold = 30
```
* `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc.
-Note: `deny` produces errors instead of warnings.
+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::...
+```
+
+### 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.
-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: `cargo clippy -- -A clippy::lint_name` will run Clippy with `lint_name` disabled and
-`cargo clippy -- -W clippy::lint_name` will run it with that enabled. This also works with lint groups. For example you
-can run Clippy with warnings for all lints enabled: `cargo clippy -- -W clippy::pedantic`
+Lints that recognize this configuration option can be found [here](https://rust-lang.github.io/rust-clippy/master/index.html#msrv)
## Contributing
## License
-Copyright 2014-2020 The Rust Project Developers
+Copyright 2014-2021 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
projects / rust.git / blobdiff