That's one way to look at it. I prefer to think of it as that the local i in B and B::i in C are the same variable, so they should behave the same, and i in B accesses the storage in A both for reading and writing.
Anyway, I agree that reading zero from B::i is wrong. Another odd thing is that it's no problem to instantiate a B by itself (and it does in fact not have any storage for the variable). Then the local i in B will behave like B::i in my example, i.e. produce 0 when read and a runtime error when written. Spontaneously I expected a runtime error already at object instantiation, but I guess this is consistent with having declared functions without definitions. Then it follows that both reading and writing such variables must be runtime errors.
