Problems of Rust: In Rust, there is a central package registry (crates.io), but there is a lack of ability to add dependencies using git URLs.

Problems of Swift: Swift can add dependencies using git URLs, but there is no central package registry.

Both languages should have a central package registry and the ability to add dependencies using git URLs, as it would make flexible dependency management much easier. For a central package registry, it makes it easier to find popular packages, but it has a problem of centralization.