Virtual base classes have special precedence and are constructed before any of their derived classes. They are constructed before any non-virtual base classes. Their construction order depends on their DAG. It is a depth-first, left-to-right order. Destructors are invoked in reverse order of constructors. These rules, although complicated, generally conform to our intuition.
The old style of just using a parenthesized argument list that implicitly called the base class constructor is allowed for single inheritance, but it is poor style even for that case. Finally, the associated destructors are called in the reverse order from constructor invocation.
