One of the biggest issues that most people have with Rust are the long compile times. One of the reasons why compile times are so long is because many projects use quite a few dependencies from crates.io.
Your dependencies have dependencies of their own, and they in turn have dependencies as well, and so on. This results in really big graphs of crates that all have to be compiled by cargo.
Sometimes however, a crate actually doesn't use anything of some of its dependencies. Then those dependencies can be removed, resulting in faster builds for that crate.
But how do you detect them? Often they sit in Cargo.toml for a long time until someone discovers they are actually unused and removes them (example). This is where
cargo-udeps comes in.
cargo-udeps is an automated tool to find dependencies that were specified in Cargo.toml but never used in the cra