Many on the C++ committee are interested in the borrow checking, but are not sure how to make it work in C++. The hard part is they cannot break compatibility with code that is legal with previous versions of C++. If there is even one pathological case where the borrow checker will reject code that doesn't have a memory leak then they will not accept it, and require whoever proposes this borrow checker to prove the absence of such a thing. (note if it rejects code that worked until the leaks mean you run out of memory they will accept that). I don't know if such a thing even exists, but if it does I'm confident that in Rust it is new code that you can write differently to avoid the bug, while with C++ that may be a very massive effort to figure out 25 year old code nobody understands anymore before you can rewrite it.

One obvious corner case: It is very common to allocate a buffer at startup and let the system clean it up when the program exits. (often this is embedded cases where the only way for the program to exit is power off). I don't know how you do this in rust (if you can - I'm not a rust expert)