Instead of disabling the borrow checker what should be possible is to promote borrows to Rc/Arc as needed. I would want to restrict this mode to one where it ca

Instead of disabling the borrow checker what should be possible is to promote borrows to Rc/Arc as needed. I would want to restrict this mode to one where it can only work locally, never publishable to crates.io. It would be particularly useful when running tests, then instead of a compile error you can also get a runtime error with better information about the cases the borrow checker was actually encountering.