SharC is a tool for checking that data is shared in a sensible way in multithreaded C programs. Programmers explicitly declare a strategy for the sharing of objects in their program. SharC then uses a combination of static and runtime checking to ensure that the program adheres to this strategy.
In real-world programs, the sharing strategy for an object can change as the program runs. SharC provides a special "sharing cast" operation so that strategy changes can be expressed. In particular, a thread can change the sharing strategy of an object when it holds the only reference to it.