<div align="center">
<h1><code>cargo-machete</code></h1>
<p>
<strong>Remove unused Rust dependencies with this one weird trick!</strong>
</p>
<p>
<a href="https://github.com/bnjbvr/cargo-machete/actions?query=workflow%3ARust"><img src="https://github.com/bnjbvr/cargo-machete/workflows/Rust/badge.svg" alt="build status" /></a>
<a href="https://matrix.to/#/#cargo-machete:delire.party"><img src="https://img.shields.io/badge/matrix-join_chat-brightgreen.svg" alt="matrix chat" /></a>
<img src="https://img.shields.io/badge/rustc-stable+-green.svg" alt="supported rustc stable" />
<a href="https://deps.rs/repo/github/bnjbvr/cargo-machete"><img src="https://deps.rs/repo/github/bnjbvr/cargo-machete/status.svg" alt="dependency status"/></a>
</p>
</div>
*Thanks to [Diego F. Goberna](https://github.com/feiss) for the lovely logo 🥰*
## Introduction
`cargo-machete` is a Cargo tool that detects unused dependencies in Rust
projects, in a fast (yet imprecise) way.
See also the [blog post](https://blog.benj.me/2022/04/27/cargo-machete/) for a
detailed writeup.
## Installation
Install `cargo-machete` with cargo:
`cargo install cargo-machete`
## Usage
Run cargo-machete in a directory that contains one or more Rust projects (using Cargo for
dependency management):
```bash
cd my-directory && cargo machete
# alternatively
cargo machete /absolute/path/to/my/directory
```
The **return code** gives an indication whether unused dependencies have been found:
- 0 if machete found no unused dependencies,
- 1 if it found at least one unused dependency,
- 2 if there was an error during processing (in which case there's no indication whether any unused
dependency was found or not).
This can be used in CI situations.
### False positives
To ignore a certain set of dependencies in a crate, add
`package.metadata.cargo-machete` to `Cargo.toml` (or `workspace.metadata.cargo-machete` to a
workspace `Cargo.toml`), and specify an `ignored` array:
For example:
```toml
[dependencies]
prost = "0.10" # Used in code generated by build.rs output, which cargo-machete cannot check
# in an individual package Cargo.toml
[package.metadata.cargo-machete]
ignored = ["prost"]
# in a workspace Cargo.toml
[workspace.metadata.cargo-machete]
ignored = ["prost"]
```
If there are too many false positives, consider using the `--with-metadata` CLI
flag, which will call `cargo metadata --all-features` to find final dependency
names, more accurate dependencies per build type, etc. âš This may modify the
`Cargo.lock` files in your projects.
### Renamed crates
Some crates have a different import name, than their dependency name (e.g.
`rustls-webpki`). This triggers false positives in `cargo-machete` when used
without the `--with-metadata` flag. To fix this you can manually rename a crate
for `cargo-machete`:
For example:
```toml
[dependencies]
rustls-webpki = "0.102"
# in an individual package Cargo.toml
[package.metadata.cargo-machete.renamed]
rustls-webpki = "webpki"
# in a workspace Cargo.toml
[workspace.metadata.cargo-machete.renamed]
rustls-webpki = "webpki"
```
This ensures that if `rustls-webpki` is no longer used in the project,
`cargo-machete` will be able to detect it (unlike with the `ignored` table).
## Docker Image
A docker image for cargo machete.
For instance, run `cargo-machete` in the `$(pwd)` directory using:
```
docker run --rm -v $(pwd):/src ghcr.io/bnjbvr/cargo-machete:latest
```
## Cargo Machete Action
A github action for cargo machete.
### Example usage
The step given by,
```
- uses: bnjbvr/cargo-machete@main
```
can be added to any workflow.
An example workflow is shown below:
```yaml
name: Cargo Machete
on:
pull_request: { branches: "*" }
jobs:
detect-unused-dependencies:
runs-on: ubuntu-latest
steps:
- name: Checkout
uses: actions/checkout@v4
- name: Machete
uses: bnjbvr/cargo-machete@main
```
## `pre-commit` Hooks
`cargo machete` can be used as a [`pre-commit`](https://pre-commit.com/) hook to check for unused dependencies before committing changes.
Add the following to your `.pre-commit-config.yaml`:
```yaml
- repo: https://github.com/bnjbvr/cargo-machete
rev: main # or a specific tag/commit
hooks:
- id: cargo-machete
```
## Contributing
[](https://www.contributor-covenant.org/version/1/4/code-of-conduct/)
We welcome community contributions to this project.
## License
[MIT license](LICENSE.md).
