Intel C++ 2016: Constructor and Destructor in unnamed union will be called.

class Optional{
public:
  union {
    Value m_value; ///< should be uninitialized ! But Intel Compiler will Constructor and Destructor here!
  };
};

Intel C++ 2016 will call Constructor and Destructor for the class inside unnamed union.

But this should be deleted and like VS2015 compiler it would be great to get a message about this.