This is what the specs says about the super expression:

  super

  super is identical to this, except that it is cast to this's base class. It is
  an error if there is no base class. It is an error to use super within a struct
  member function. (Only class Object has no base class.) super is not allowed in
  struct member functions. If a member function is called with an explicit
  reference to super, a non-virtual call is made.

Note that using super in structs is forbidden is said twice (once before the clarification in parenthesis, and one after). Maybe this can be rephrased as:

  super

  super is identical to this, except that it is cast to this's base class. It is
  an error if there is no base class (note that only class Object has no base
  class). It is an error to use super within a struct member function. If a
  member function is called with an explicit reference to super, a non-virtual
  call is made.

This goes for D2 too.