3 [![Build Status](https://travis-ci.org/rust-lang/rust-clippy.svg?branch=master)](https://travis-ci.org/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 290 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 Now you can run Clippy by invoking `cargo clippy`.
74 If it says that it can't find the `clippy` subcommand, please run `rustup self update`
76 ### Running Clippy from the command line without installing it
78 To have cargo compile your crate with Clippy without Clippy installation
79 in your code, you can use:
82 cargo run --bin cargo-clippy --manifest-path=path_to_clippys_Cargo.toml
85 *[Note](https://github.com/rust-lang/rust-clippy/wiki#a-word-of-warning):*
86 Be sure that Clippy was compiled with the same version of rustc that cargo invokes here!
90 You can add Clippy to Travis CI in the same way you use it locally:
98 - rustup component add clippy
101 # if you want the build job to fail when encountering warnings, use
102 - cargo clippy -- -D warnings
103 # in order to also check tests and none-default crate features, use
104 - cargo clippy --all-targets --all-features -- -D warnings
109 It might happen that clippy is not available for a certain nightly release.
110 In this case you can try to conditionally install clippy from the git repo.
117 - rustup component add clippy --toolchain=nightly || cargo install --git https://github.com/rust-lang/rust-clippy/ --force clippy
123 Some lints can be configured in a TOML file named `clippy.toml` or `.clippy.toml`. It contains a basic `variable = value` mapping eg.
126 blacklisted-names = ["toto", "tata", "titi"]
127 cyclomatic-complexity-threshold = 30
130 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
131 meaning of the variables.
133 To deactivate the “for further information visit *lint-link*” message you can
134 define the `CLIPPY_DISABLE_DOCS_LINKS` environment variable.
136 ### Allowing/denying lints
138 You can add options to your code to `allow`/`warn`/`deny` Clippy lints:
140 * the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy::all)]`)
142 * all lints using both the `clippy` and `clippy::pedantic` lint groups (`#![deny(clippy::all)]`,
143 `#![deny(clippy::pedantic)]`). Note that `clippy::pedantic` contains some very aggressive
144 lints prone to false positives.
146 * only some lints (`#![deny(clippy::single_match, clippy::box_vec)]`, etc)
148 * `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
150 Note: `deny` produces errors instead of warnings.
152 Note: To use the new `clippy::lint_name` syntax, a recent compiler has to be used
153 currently. If you want to compile your code with the stable toolchain you can use a `cfg_attr` to
154 activate the `tool_lints` feature:
156 #![cfg_attr(feature = "cargo-clippy", allow(clippy::lint_name))]
159 For this to work you have to use Clippy on the nightly toolchain: `cargo +nightly clippy`. If you
160 want to use Clippy with the stable toolchain, you can stick to the old unscoped method to
161 enable/disable Clippy lints until `tool_lints` are stable:
163 #![cfg_attr(feature = "cargo-clippy", allow(clippy_lint))]
166 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 lint_name` will run clippy with `lint_name` disabled and `cargo clippy -- -W lint_name` will run it with that enabled. On newer compilers you may need to use `clippy::lint_name` instead.
170 Copyright 2014-2018 The Rust Project Developers
172 Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
173 http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
174 <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
175 option. All files in the project carrying such notice may not be
176 copied, modified, or distributed except according to those terms.