One thing that I think we'll have to deal with at some point in the next two years or so is that although using the borrow checker will be incremental on (say)

One thing that I think we'll have to deal with at some point in the next two years or so is that although using the borrow checker will be incremental on (say) functions, the actual design of said borrow checker needs to be more integrated than incremental i.e. currently we can catch lifetime related bugs but you can't properly express (say) invalidating a pointer into a container by calling popFront.