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