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7 [![License: MPL-2.0](https://img.shields.io/crates/l/clippy.svg)](#License)
9 A collection of lints to catch common mistakes and improve your Rust code.
14 * [Usage instructions](#usage)
15 * [Configuration](#configuration)
20 Since this is a tool for helping the developer of a library or application
21 write better code, it is recommended not to include clippy as a hard dependency.
22 Options include using it as an optional dependency, as a cargo subcommand, or
23 as an included feature during build. All of these options are detailed below.
25 As a general rule clippy will only work with the *latest* Rust nightly for now.
27 ### Optional dependency
29 If you want to make clippy an optional dependency, you can do the following:
35 clippy = {version = "*", optional = true}
41 And, in your `main.rs` or `lib.rs`:
44 #![cfg_attr(feature="clippy", feature(plugin))]
46 #![cfg_attr(feature="clippy", plugin(clippy))]
49 Then build by enabling the feature: `cargo build --features "clippy"`
51 Instead of adding the `cfg_attr` attributes you can also run clippy on demand:
52 `cargo rustc --features clippy -- -Z no-trans -Z extra-plugins=clippy`
53 (the `-Z no trans`, while not necessary, will stop the compilation process after
54 typechecking (and lints) have completed, which can significantly reduce the runtime).
56 ### As a cargo subcommand (`cargo clippy`)
58 An alternate way to use clippy is by installing clippy through cargo as a cargo
65 Now you can run clippy by invoking `cargo clippy`, or
66 `rustup run nightly cargo clippy` directly from a directory that is usually
69 In case you are not using rustup, you need to set the environment flag
70 `SYSROOT` during installation so clippy knows where to find `librustc` and
74 SYSROOT=/path/to/rustc/sysroot cargo install clippy
77 ### Running clippy from the command line without installing
79 To have cargo compile your crate with clippy without needing `#![plugin(clippy)]`
80 in your code, you can use:
83 cargo rustc -- -L /path/to/clippy_so/dir/ -Z extra-plugins=clippy
86 *[Note](https://github.com/rust-lang-nursery/rust-clippy/wiki#a-word-of-warning):*
87 Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
89 ### As a Compiler Plugin
91 *Note:* This is not a recommended installation method.
93 Since stable Rust is backwards compatible, you should be able to
94 compile your stable programs with nightly Rust with clippy plugged in to
97 Add in your `Cargo.toml`:
104 You then need to add `#![feature(plugin)]` and `#![plugin(clippy)]` to the top
105 of your crate entry point (`main.rs` or `lib.rs`).
118 Some(y) => println!("{:?}", y),
124 Produces this warning:
127 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
128 src/main.rs:8 match x {
129 src/main.rs:9 Some(y) => println!("{:?}", y),
130 src/main.rs:10 _ => ()
132 src/main.rs:8:5: 11:6 help: Try
133 if let Some(y) = x { println!("{:?}", y) }
138 Some lints can be configured in a `clippy.toml` file. It contains basic `variable = value` mapping eg.
141 blacklisted-names = ["toto", "tata", "titi"]
142 cyclomatic-complexity-threshold = 30
145 See the wiki for more information about which lints can be configured and the
146 meaning of the variables.
148 You can also specify the path to the configuration file with:
151 #![plugin(clippy(conf_file="path/to/clippy's/configuration"))]
154 To deactivate the “for further information visit *wiki-link*” message you can
155 define the `CLIPPY_DISABLE_WIKI_LINKS` environment variable.
157 ### Allowing/denying lints
159 You can add options to `allow`/`warn`/`deny`:
161 * the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy)]`)
163 * all lints using both the `clippy` and `clippy_pedantic` lint groups (`#![deny(clippy)]`,
164 `#![deny(clippy_pedantic)]`). Note that `clippy_pedantic` contains some very aggressive
165 lints prone to false positives.
167 * only some lints (`#![deny(single_match, box_vec)]`, etc)
169 * `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
171 Note: `deny` produces errors instead of warnings.
173 For convenience, `cargo clippy` automatically defines a `cargo-clippy`
174 features. This lets you set lints level and compile with or without clippy
178 #[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
183 There are 209 lints included in this crate:
184 https://rust-lang-nursery.github.io/rust-clippy/master/index.html
186 More to come, please [file an issue](https://github.com/rust-lang-nursery/rust-clippy/issues) if you have ideas!
190 Licensed under [MPL](https://www.mozilla.org/MPL/2.0/).
191 If you're having issues with the license, let me know and I'll try to change it to something more permissive.