Crash in C++ code due to undefined behaviour or compiler bug?

Question

I am experiencing strange crashes. And I wonder whether it is a bug in my code, or the compiler. When I compile the following C++ code with Microsoft Visual Studio 2010 as an op

Answer 1

You take &v1 into c.p and later using operator ++ you advance it. You cannot rely on the ordering of the stack, therefore comes undefined behavior ((&v1)+1 != &v2)