Yes, we were already using it on Windows to program COM in the mid-90's.

The borrow checker is predated by Cyclone and other work on region systems. Rust added more polish, but none of the basic ideas are new.

Of course, I'm aware that work on region systems dates back to the mid 90's, which is why I called Rust's borrow checker an “innovation” (the first time a product form factor or feature successfully makes it into a market) rather than an “invention” (coming up with a product concept that didn't exist before).