3 [![Build Status](https://travis-ci.org/rust-lang-nursery/rust-clippy.svg?branch=master)](https://travis-ci.org/rust-lang-nursery/rust-clippy)
4 [![Windows build status](https://ci.appveyor.com/api/projects/status/github/rust-lang-nursery/rust-clippy?svg=true)](https://ci.appveyor.com/project/rust-lang-nursery/rust-clippy)
5 [![Current Version](https://meritbadge.herokuapp.com/clippy)](https://crates.io/crates/clippy)
6 [![License: MPL-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 265 lints included in this crate!](https://rust-lang-nursery.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` (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-nursery/rust-clippy/issues) if you have ideas!
27 * [Usage instructions](#usage)
28 * [Configuration](#configuration)
33 Since this is a tool for helping the developer of a library or application
34 write better code, it is recommended not to include clippy as a hard dependency.
35 Options include using it as an optional dependency, as a cargo subcommand, or
36 as an included feature during build. All of these options are detailed below.
38 As a general rule clippy will only work with the *latest* Rust nightly for now.
40 To install Rust nightly, the recommended way is to use [rustup](https://rustup.rs/):
43 rustup install nightly
46 ### As a cargo subcommand (`cargo clippy`)
48 One way to use clippy is by installing clippy through cargo as a cargo
52 cargo +nightly install clippy
55 (The `+nightly` is not necessary if your default `rustup` install is nightly)
57 Now you can run clippy by invoking `cargo +nightly clippy`.
59 To update the subcommand together with the latest nightly use the [rust-update](rust-update) script or run:
63 cargo +nightly install --force clippy
66 In case you are not using rustup, you need to set the environment flag
67 `SYSROOT` during installation so clippy knows where to find `librustc` and
71 SYSROOT=/path/to/rustc/sysroot cargo install clippy
74 ### Running clippy from the command line without installing it
76 To have cargo compile your crate with clippy without clippy installation
77 in your code, you can use:
80 cargo run --bin cargo-clippy --manifest-path=path_to_clippys_Cargo.toml
83 *[Note](https://github.com/rust-lang-nursery/rust-clippy/wiki#a-word-of-warning):*
84 Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
88 Some lints can be configured in a TOML file named with `clippy.toml` or `.clippy.toml`. It contains basic `variable = value` mapping eg.
91 blacklisted-names = ["toto", "tata", "titi"]
92 cyclomatic-complexity-threshold = 30
95 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
96 meaning of the variables.
98 To deactivate the “for further information visit *lint-link*” message you can
99 define the `CLIPPY_DISABLE_DOCS_LINKS` environment variable.
101 ### Allowing/denying lints
103 You can add options to `allow`/`warn`/`deny`:
105 * the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy)]`)
107 * all lints using both the `clippy` and `clippy_pedantic` lint groups (`#![deny(clippy)]`,
108 `#![deny(clippy_pedantic)]`). Note that `clippy_pedantic` contains some very aggressive
109 lints prone to false positives.
111 * only some lints (`#![deny(single_match, box_vec)]`, etc)
113 * `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
115 Note: `deny` produces errors instead of warnings.
117 For convenience, `cargo clippy` automatically defines a `cargo-clippy`
118 feature. This lets you set lint levels and compile with or without clippy
122 #[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
127 Sometimes, rustc moves forward without clippy catching up. Therefore updating
128 rustc may leave clippy a non-functional state until we fix the resulting
131 You can use the [rust-update](rust-update) script to update rustc only if
132 clippy would also update correctly.
136 Licensed under [MPL](https://www.mozilla.org/MPL/2.0/).
137 If you're having issues with the license, let me know and I'll try to change it to something more permissive.