Comment by steveklabnik

> declare binaries in your Cargo.toml, for example. It also, AIUI, requires a specific source layout - binaries need to be named `main.rs` or be in `src/bin`.

It does not. Those are the defaults. You can configure something else if you wish. Most people just don’t bother, because there’s not really advantages to breaking with default locations 99% of the time.