Ah, I see. True, Rust has a more restricted model that allows it to track lifetimes more precisely. As far as I know, Clang will omit reference counting if it can be statically determined but of course it has fewer optimization opportunities here. In the end, the two approaches are not entirely dissimilar: ARC uses static analysis to detect dependencies and will fallback to dynamic RC n complex scenarios; while Rust enforces certain rules that only allow most basic dependencies and requires the user to mark these by using dedicated tools.