It's absolutely possible, because the hardware doesn't care about your compilation model: you can mix normal pointers and capabilities as you wish. A challenge is that it's easy to go from capability -> pointer, but harder to go from pointer -> capability -- where do the extra capability bits come from? CHERI C provides a default ("inherit capability bits from the DDC") but I'm not sure that's what I would choose to do.

Problem is, there's lots of unsafe code that casts *mut T to &mut T (usually after checking T is valid and whatnot). If &mut T didn't use capabilities, this kind of unsafe code would end up not taking advantage of the CHERI capability checking, which would be unfortunate.

I don't think this is actually a problem, since when casting from `&mut T` to `*mut T`, the returned pointer can only access the data (the T value) directly behind the reference.

The raw pointer would be synthesised with the capability for only the pointee of the original reference.