3 [![Build Status](https://travis-ci.com/rust-lang/rust-clippy.svg?branch=master)](https://travis-ci.com/rust-lang/rust-clippy)
4 [![Windows Build status](https://ci.appveyor.com/api/projects/status/id677xpw1dguo7iw?svg=true)](https://ci.appveyor.com/project/rust-lang-libs/rust-clippy)
5 [![Current Version](https://meritbadge.herokuapp.com/clippy)](https://crates.io/crates/clippy)
6 [![License: MIT/Apache-2.0](https://img.shields.io/crates/l/clippy.svg)](#license)
8 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
10 [There are 291 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
12 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
14 * `clippy::all` (everything that has no false positives)
15 * `clippy::pedantic` (everything)
16 * `clippy::nursery` (new lints that aren't quite ready yet)
17 * `clippy::style` (code that should be written in a more idiomatic way)
18 * `clippy::complexity` (code that does something simple but in a complex way)
19 * `clippy::perf` (code that can be written in a faster way)
20 * `clippy::cargo` (checks against the cargo manifest)
21 * **`clippy::correctness`** (code that is just outright wrong or very very useless)
23 More to come, please [file an issue](https://github.com/rust-lang/rust-clippy/issues) if you have ideas!
25 Only the following of those categories are enabled by default:
28 * `clippy::correctness`
29 * `clippy::complexity`
32 Other categories need to be enabled in order for their lints to be executed.
36 * [Usage instructions](#usage)
37 * [Configuration](#configuration)
42 Since this is a tool for helping the developer of a library or application
43 write better code, it is recommended not to include Clippy as a hard dependency.
44 Options include using it as an optional dependency, as a cargo subcommand, or
45 as an included feature during build. These options are detailed below.
47 ### As a cargo subcommand (`cargo clippy`)
49 One way to use Clippy is by installing Clippy through rustup as a cargo
52 #### Step 1: Install rustup
54 You can install [rustup](http://rustup.rs/) on supported platforms. This will help
55 us install Clippy and its dependencies.
57 If you already have rustup installed, update to ensure you have the latest
64 #### Step 2: Install Clippy
66 Once you have rustup and the latest stable release (at least Rust 1.29) installed, run the following command:
69 rustup component add clippy
72 #### Step 3: Run Clippy
74 Now you can run Clippy by invoking the following command:
80 If it says that it can't find the `clippy` subcommand, please run `rustup self update`.
82 ### Running Clippy from the command line without installing it
84 To have cargo compile your crate with Clippy without Clippy installation
85 in your code, you can use:
88 cargo run --bin cargo-clippy --manifest-path=path_to_clippys_Cargo.toml
91 *[Note](https://github.com/rust-lang/rust-clippy/wiki#a-word-of-warning):*
92 Be sure that Clippy was compiled with the same version of rustc that cargo invokes here!
96 You can add Clippy to Travis CI in the same way you use it locally:
104 - rustup component add clippy
107 # if you want the build job to fail when encountering warnings, use
108 - cargo clippy -- -D warnings
109 # in order to also check tests and none-default crate features, use
110 - cargo clippy --all-targets --all-features -- -D warnings
115 It might happen that Clippy is not available for a certain nightly release.
116 In this case you can try to conditionally install Clippy from the git repo.
123 - rustup component add clippy --toolchain=nightly || cargo install --git https://github.com/rust-lang/rust-clippy/ --force clippy
129 Some lints can be configured in a TOML file named `clippy.toml` or `.clippy.toml`. It contains a basic `variable = value` mapping eg.
132 blacklisted-names = ["toto", "tata", "titi"]
133 cyclomatic-complexity-threshold = 30
136 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
137 meaning of the variables.
139 To deactivate the “for further information visit *lint-link*” message you can
140 define the `CLIPPY_DISABLE_DOCS_LINKS` environment variable.
142 ### Allowing/denying lints
144 You can add options to your code to `allow`/`warn`/`deny` Clippy lints:
146 * the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy::all)]`)
148 * all lints using both the `clippy` and `clippy::pedantic` lint groups (`#![deny(clippy::all)]`,
149 `#![deny(clippy::pedantic)]`). Note that `clippy::pedantic` contains some very aggressive
150 lints prone to false positives.
152 * only some lints (`#![deny(clippy::single_match, clippy::box_vec)]`, etc)
154 * `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
156 Note: `deny` produces errors instead of warnings.
158 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`
162 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).
166 Copyright 2014-2019 The Rust Project Developers
168 Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
169 http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
170 <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
171 option. All files in the project carrying such notice may not be
172 copied, modified, or distributed except according to those terms.