I think variant after move is like int without initialization: int i; cout << i; // don't do this If the fact, that moved-from objects are only good for destruction or assignment-to is accepted, then invariants for moved-from objects are allowed to be violated.
I completely agree with the notion that a moved-from object simply should not be used in any manner. It is interestingly divergent from the typical Design by Contract idiom. It is much more usual, in my experience for the class-invariants to hold up to and including entry to the destructor. It seems that this divergence is of little importance to users of the language since we are not explicitly interested in calling the destructor. If I understand correctly the standard is divergent to allow sensible compiler implementations of clean-up code for moved-from objects. Hence I am in agreement with your sentiment, but wanted to point out that this is unusual use of the DbC rules. Unusual in this case is not meant to imply bad; it is rather interesting.
Kris
Regards, Neil Groves