[arnsholt]

Ownership serves another important purpose: it determines when a value is freed.

[zelphirkalt]

I guess it is then a necessary complication of the language, as it doesn't have garbage collection, and as such doesn't notice, when values go out of scope of all closures that reference them?

[steveklabnik]

Yes, but it’s more subtle than that. What Rust does is track when the object goes out of scope, and will make sure that any closures that reference it live for a shorter time than that. Sort of backwards of what you’re asking.

[pclmulqdq]

The borrow checker is a compile-time garbage collector. If you think about it in that sense, you can understand a lot of the ways it restricts you.