[ohazi]

This is not how ARC works. ARC keeps a count (at runtime) of the number of references to dynamically allocated objects. Every time you create a new reference to an object, the count is incremented, and every time a reference goes out of scope, the count is decremented. When the count reaches zero, the memory is either freed immediately or marked as free-able for later.

Your bit about compile-time code analysis to automatically insert the cleanup code when data is no longer reachable is actually pretty similar to what Rust does today with owned pointers. The downside is that this doesn't work with "normal" code -- you need certain annotations for the compiler to be able to perform this task correctly. In Rust this is done via region pointers (lifetime parameters) and borrow checking.