clippy

Clippy is Rust's official linter that serves as an essential code quality tool, providing comprehensive analysis to catch common mistakes and improve code quality. It's maintained by the Rust team and integrated into the standard Rust toolchain.

Key Features:

Extensive Rule Coverage: Over 750+ categorized lints covering correctness, performance, style, complexity, and pedantic guidelines
Intelligent Categorization: Organizes lints by severity - correctness (bugs), performance (optimizations), style (idiomatic patterns), complexity (simplification), and pedantic (strict standards)
Automatic Fixes: Machine-applicable suggestions that can automatically fix many issues with cargo clippy --fix
MSRV Support: Respects Minimum Supported Rust Version (MSRV) to ensure compatibility with older Rust versions
Cargo Integration: Seamlessly integrates with Cargo build system for zero-configuration usage
Configurable Rules: Extensive configuration options through clippy.toml for project-specific requirements
Performance Focus: Identifies optimization opportunities and suggests more efficient Rust patterns
Safety Enforcement: Helps prevent common programming errors and promotes memory-safe, thread-safe code

clippy documentation

Version in MegaLinter: 0.1.88
Visit Official Web Site
See How to configure clippy rules
See How to disable clippy rules in files
See Index of problems detected by clippy

Configuration in MegaLinter

Enable clippy by adding RUST_CLIPPY in ENABLE_LINTERS variable
Disable clippy by adding RUST_CLIPPY in DISABLE_LINTERS variable

Variable	Description	Default value
RUST_CLIPPY_ARGUMENTS	User custom arguments to add in linter CLI call Ex: `-s --foo "bar"`
RUST_CLIPPY_COMMAND_REMOVE_ARGUMENTS	User custom arguments to remove from command line before calling the linter Ex: `-s --foo "bar"`
RUST_CLIPPY_CLI_LINT_MODE	Override default CLI lint mode ⚠️ As default value is project, overriding might not work - `file`: Calls the linter for each file - `list_of_files`: Call the linter with the list of files as argument - `project`: Call the linter from the root of the project	`project`
RUST_CLIPPY_FILE_EXTENSIONS	Allowed file extensions. `"*"` matches any extension, `""` matches empty extension. Empty list excludes all files Ex: `[".py", ""]`	`[".rs"]`
RUST_CLIPPY_FILE_NAMES_REGEX	File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files Ex: `["Dockerfile(-.+)?", "Jenkinsfile"]`	Include every file
RUST_CLIPPY_PRE_COMMANDS	List of bash commands to run before the linter	None
RUST_CLIPPY_POST_COMMANDS	List of bash commands to run after the linter	None
RUST_CLIPPY_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling RUST_CLIPPY and its pre/post commands	None
RUST_CLIPPY_CONFIG_FILE	clippy configuration file nameUse `LINTER_DEFAULT` to let the linter find it	`.clippy.toml`
RUST_CLIPPY_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
RUST_CLIPPY_DISABLE_ERRORS	Run linter but consider errors as warnings	`false`
RUST_CLIPPY_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	`0`
RUST_CLIPPY_CLI_EXECUTABLE	Override CLI executable	`['cargo-clippy']`

IDE Integration

Use clippy in your favorite IDE to catch errors before MegaLinter !

	IDE	Extension Name	Install
	Visual Studio Code	rust-analyzer

MegaLinter Flavors

This linter is available in the following flavors

Flavor	Description	Embedded linters
all	Default MegaLinter Flavor	127
cupcake	MegaLinter for the most commonly used languages	88
rust	Optimized for RUST based projects	51

Behind the scenes

How are identified applicable files

File extensions: .rs

How the linting is performed

clippy is called once on the whole project directory (project CLI lint mode)

filtering can not be done using MegaLinter configuration variables,it must be done using clippy configuration or ignore file (if existing)
VALIDATE_ALL_CODEBASE: false doesn't make clippy analyze only updated files

Example calls

cargo-clippy

Help content

Checks a package to catch common mistakes and improve your Rust code.

Usage:
    cargo clippy [OPTIONS] [--] [<ARGS>...]

Common options:
    --no-deps                Run Clippy only on the given crate, without linting the dependencies
    --fix                    Automatically apply lint suggestions. This flag implies --no-deps and --all-targets
    -h, --help               Print this message
    -V, --version            Print version info and exit
    --explain [LINT]         Print the documentation for a given lint

See all options with cargo check --help.

Allowing / Denying lints

To allow or deny a lint from the command line you can use cargo clippy -- with:

    -W / --warn [LINT]       Set lint warnings
    -A / --allow [LINT]      Set lint allowed
    -D / --deny [LINT]       Set lint denied
    -F / --forbid [LINT]     Set lint forbidden

You can use tool lints to allow or deny lints from your code, e.g.:

    #[allow(clippy::needless_lifetimes)]

Manifest Options:
    --manifest-path <PATH>  Path to Cargo.toml
    --frozen                Require Cargo.lock and cache are up to date
    --locked                Require Cargo.lock is up to date
    --offline               Run without accessing the network

Installation on mega-linter Docker image

Cargo packages (Rust):
- clippy