cargo-machete is a Cargo tool that detects unused dependencies in Rust
projects, in a fast (yet imprecise) way.
See also the blog post for a detailed writeup.
Install cargo-machete with cargo:
cargo install cargo-machete
Run cargo-machete in a directory that contains one or more Rust projects (using Cargo for dependency management):
cd my-directory && cargo machete
# alternatively
cargo machete /absolute/path/to/my/directoryThe 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.
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:
[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. ⚠ This may modify the
Cargo.lock files in your projects.
A github action for cargo machete.
The step given by,
- uses: bnjbvr/cargo-machete@main
can be added to any workflow.
An example workflow is shown below:
name: Cargo Machete
on:
pull_request: { branches: "*" }
jobs:
build:
runs-on: ubuntu-latest
steps:
- name: Checkout
uses: actions/checkout@v3
- name: Machete
uses: bnjbvr/cargo-machete@main
We welcome community contributions to this project.