crates.io is package repository, cargo is a build tool, rustc is the compiler, and they all three are separate entities. rustc as far as I know operates solely

crates.io is package repository, cargo is a build tool, rustc is the compiler, and they all three are separate entities. rustc as far as I know operates solely on local files, and has no built-in logic or knowledge about crates.io. And cargo can be configured to use different repository than crates.io, which can have different naming policy