When a virtual function is called directly or indirectly
from a constructor or from a destructor,
including during the construction or destruction
of the class's non-static data members,
and the object to which the call applies
is the object (call it
x) under construction or destruction,
the function called is the final overrider in the constructor's or destructor's class
and not one overriding it in a more-derived class
.If the virtual function call uses an explicit class member access (
[expr.ref])
and the object expression refers to the complete object of
x
or one of that object's base class subobjects
but not
x or one of its base class subobjects,
the behavior is undefined
.