138 lines
5.0 KiB
Markdown
138 lines
5.0 KiB
Markdown
# rust-clippy
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[](https://travis-ci.org/rust-lang-nursery/rust-clippy)
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[](https://ci.appveyor.com/project/rust-lang-nursery/rust-clippy)
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[](https://crates.io/crates/clippy)
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[](#license)
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A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
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[There are 258 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)
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We have a bunch of lint categories to allow you to choose how much clippy is supposed to ~~annoy~~ help you:
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* `clippy` (everything that has no false positives)
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* `clippy_pedantic` (everything)
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* `clippy_nursery` (new lints that aren't quite ready yet)
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* `clippy_style` (code that should be written in a more idiomatic way)
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* `clippy_complexity` (code that does something simple but in a complex way)
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* `clippy_perf` (code that can be written in a faster way)
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* `clippy_cargo` (checks against the cargo manifest)
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* **`clippy_correctness`** (code that is just outright wrong or very very useless)
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More to come, please [file an issue](https://github.com/rust-lang-nursery/rust-clippy/issues) if you have ideas!
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Table of contents:
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* [Usage instructions](#usage)
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* [Configuration](#configuration)
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* [License](#license)
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## Usage
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Since this is a tool for helping the developer of a library or application
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write better code, it is recommended not to include clippy as a hard dependency.
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Options include using it as an optional dependency, as a cargo subcommand, or
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as an included feature during build. All of these options are detailed below.
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As a general rule clippy will only work with the *latest* Rust nightly for now.
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To install Rust nightly, the recommended way is to use [rustup](https://rustup.rs/):
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```terminal
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rustup install nightly
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```
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### As a cargo subcommand (`cargo clippy`)
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One way to use clippy is by installing clippy through cargo as a cargo
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subcommand.
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```terminal
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cargo +nightly install clippy
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```
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(The `+nightly` is not necessary if your default `rustup` install is nightly)
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Now you can run clippy by invoking `cargo +nightly clippy`.
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To update the subcommand together with the latest nightly use the [rust-update](rust-update) script or run:
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```terminal
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rustup update nightly
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cargo +nightly install --force clippy
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```
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In case you are not using rustup, you need to set the environment flag
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`SYSROOT` during installation so clippy knows where to find `librustc` and
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similar crates.
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```terminal
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SYSROOT=/path/to/rustc/sysroot cargo install clippy
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```
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### Running clippy from the command line without installing it
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To have cargo compile your crate with clippy without clippy installation
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in your code, you can use:
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```terminal
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cargo run --bin cargo-clippy --manifest-path=path_to_clippys_Cargo.toml
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```
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*[Note](https://github.com/rust-lang-nursery/rust-clippy/wiki#a-word-of-warning):*
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Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
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## Configuration
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Some lints can be configured in a TOML file named with `clippy.toml` or `.clippy.toml`. It contains basic `variable = value` mapping eg.
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```toml
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blacklisted-names = ["toto", "tata", "titi"]
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cyclomatic-complexity-threshold = 30
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```
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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
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meaning of the variables.
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To deactivate the “for further information visit *lint-link*” message you can
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define the `CLIPPY_DISABLE_DOCS_LINKS` environment variable.
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### Allowing/denying lints
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You can add options to `allow`/`warn`/`deny`:
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* the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy)]`)
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* all lints using both the `clippy` and `clippy_pedantic` lint groups (`#![deny(clippy)]`,
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`#![deny(clippy_pedantic)]`). Note that `clippy_pedantic` contains some very aggressive
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lints prone to false positives.
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* only some lints (`#![deny(single_match, box_vec)]`, etc)
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* `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
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Note: `deny` produces errors instead of warnings.
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For convenience, `cargo clippy` automatically defines a `cargo-clippy`
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feature. This lets you set lint levels and compile with or without clippy
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transparently:
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```rust
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#[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
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```
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## Updating rustc
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Sometimes, rustc moves forward without clippy catching up. Therefore updating
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rustc may leave clippy a non-functional state until we fix the resulting
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breakage.
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You can use the [rust-update](rust-update) script to update rustc only if
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clippy would also update correctly.
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## License
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Licensed under [MPL](https://www.mozilla.org/MPL/2.0/).
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If you're having issues with the license, let me know and I'll try to change it to something more permissive.
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