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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 code.
10 [There are 209 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)
12 More to come, please [file an issue](https://github.com/rust-lang-nursery/rust-clippy/issues) if you have ideas!
16 * [Usage instructions](#usage)
17 * [Configuration](#configuration)
22 Since this is a tool for helping the developer of a library or application
23 write better code, it is recommended not to include clippy as a hard dependency.
24 Options include using it as an optional dependency, as a cargo subcommand, or
25 as an included feature during build. All of these options are detailed below.
27 As a general rule clippy will only work with the *latest* Rust nightly for now.
29 ### Optional dependency
31 If you want to make clippy an optional dependency, you can do the following:
37 clippy = {version = "*", optional = true}
43 And, in your `main.rs` or `lib.rs`:
46 #![cfg_attr(feature="clippy", feature(plugin))]
48 #![cfg_attr(feature="clippy", plugin(clippy))]
51 Then build by enabling the feature: `cargo build --features "clippy"`
53 Instead of adding the `cfg_attr` attributes you can also run clippy on demand:
54 `cargo rustc --features clippy -- -Z no-trans -Z extra-plugins=clippy`
55 (the `-Z no trans`, while not necessary, will stop the compilation process after
56 typechecking (and lints) have completed, which can significantly reduce the runtime).
58 ### As a cargo subcommand (`cargo clippy`)
60 An alternate way to use clippy is by installing clippy through cargo as a cargo
67 Now you can run clippy by invoking `cargo clippy`, or
68 `rustup run nightly cargo clippy` directly from a directory that is usually
71 In case you are not using rustup, you need to set the environment flag
72 `SYSROOT` during installation so clippy knows where to find `librustc` and
76 SYSROOT=/path/to/rustc/sysroot cargo install clippy
79 ### Running clippy from the command line without installing
81 To have cargo compile your crate with clippy without needing `#![plugin(clippy)]`
82 in your code, you can use:
85 cargo rustc -- -L /path/to/clippy_so/dir/ -Z extra-plugins=clippy
88 *[Note](https://github.com/rust-lang-nursery/rust-clippy/wiki#a-word-of-warning):*
89 Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
91 ### As a Compiler Plugin
93 *Note:* This is not a recommended installation method.
95 Since stable Rust is backwards compatible, you should be able to
96 compile your stable programs with nightly Rust with clippy plugged in to
99 Add in your `Cargo.toml`:
106 You then need to add `#![feature(plugin)]` and `#![plugin(clippy)]` to the top
107 of your crate entry point (`main.rs` or `lib.rs`).
120 Some(y) => println!("{:?}", y),
126 Produces this warning:
129 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
130 src/main.rs:8 match x {
131 src/main.rs:9 Some(y) => println!("{:?}", y),
132 src/main.rs:10 _ => ()
134 src/main.rs:8:5: 11:6 help: Try
135 if let Some(y) = x { println!("{:?}", y) }
140 Some lints can be configured in a `clippy.toml` file. It contains basic `variable = value` mapping eg.
143 blacklisted-names = ["toto", "tata", "titi"]
144 cyclomatic-complexity-threshold = 30
147 See the wiki for more information about which lints can be configured and the
148 meaning of the variables.
150 You can also specify the path to the configuration file with:
153 #![plugin(clippy(conf_file="path/to/clippy's/configuration"))]
156 To deactivate the “for further information visit *wiki-link*” message you can
157 define the `CLIPPY_DISABLE_DOCS_LINKS` environment variable.
159 ### Allowing/denying lints
161 You can add options to `allow`/`warn`/`deny`:
163 * the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy)]`)
165 * all lints using both the `clippy` and `clippy_pedantic` lint groups (`#![deny(clippy)]`,
166 `#![deny(clippy_pedantic)]`). Note that `clippy_pedantic` contains some very aggressive
167 lints prone to false positives.
169 * only some lints (`#![deny(single_match, box_vec)]`, etc)
171 * `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
173 Note: `deny` produces errors instead of warnings.
175 For convenience, `cargo clippy` automatically defines a `cargo-clippy`
176 features. This lets you set lints level and compile with or without clippy
180 #[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
185 Licensed under [MPL](https://www.mozilla.org/MPL/2.0/).
186 If you're having issues with the license, let me know and I'll try to change it to something more permissive.