Cargo Shear ✂️ 🐑

Detect and remove unused dependencies from Cargo.toml in Rust projects.

Does not with dependencies from macros (yet).

Usage

cargo install cargo-shear
cargo shear --fix

Exit Code (for CI)

The exit code gives an indication whether unused dependencies have been found:

• 0 if 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).

Technique

1. use the cargo_metadata crate to list all dependencies specified in [workspace.dependencies] and [dependencies]
2. iterate through all package targets to locate all Rust files
3. use syn to parse these Rust files and extract imports
4. identify the difference between the imports and the package dependencies

TODO

• make the reporting more granular for [dependencies], [dev-dependencies] and [build-dependencies]
• add tests
• print things nicely
• ignore [package.metadata.cargo-shear] ignored = ["crate"]

Prior Arts

• https://github.com/est31/cargo-udeps
• https://github.com/bnjbvr/cargo-machete

Trophy Cases

• -7 lines from oxc
• -59 lines from rspack
• -39 lines from rolldown
• -12 lines ast-grep commit1 commit2
• -66 lines biome