If you're getting confusing compile errors, especially any involving type annotations, check that you wrote enough of your code. If you produce results that you don't read/use, for example, the compiler will still want to determine their definite type. Adding more code to give the compiler a hint can spare adding optional type annotations.
Adding content progressively.
Installation
Install Rust via https://rustup.rs rather than Homebrew.
https://github.com/mozilla/grcov#example-how-to-generate-source-based-coverage-for-a-rust-project
Preferences
Top 250 https://lib.rs/std
Troubleshooting
If you're getting confusing compile errors, especially any involving type annotations, check that you wrote enough of your code. If you produce results that you don't read/use, for example, the compiler will still want to determine their definite type. Adding more code to give the compiler a hint can spare adding optional type annotations.
Reference
Read:
Use https://docs.rs for crate documentation (need to scroll up on page to display within-crate search bar).