Function cargo::util::restricted_names::validate_package_name

pub fn validate_package_name(
    name: &str,
    what: &str,
    help: &str
) -> CargoResult<()>

Check the base requirements for a package name.

This can be used for other things than package names, to enforce some level of sanity. Note that package names have other restrictions elsewhere. cargo new has a few restrictions, such as checking for reserved names. crates.io has even more restrictions.