I'm improvising here, but if pins can be switched from read to write (but can only be in one of those at a time), then in Rust you should be able to use the bor

I'm improvising here, but if pins can be switched from read to write (but can only be in one of those at a time), then in Rust you should be able to use the borrow checker to provide additional guarantees. As long as a pin is borrowed by a ReadPin, you can't create a WritePin, and viceversa. As you say, you can use the same approach in C++, but this is one reason why the approach is extra interesting in Rust.