parse.y question

[Sergiy P. Zhenochin]

        Hello,

Here are several  partial nonterminals and productions from gcj parse.y:



class_declaration:
    CLASS_TK identifier super interfaces
      {    create_class (0, $2, $3, $4); }
     class_body

where

 identifier:
     ID_TK        ;

I'f I'm correct, ID_TK is returned after the latter production is
reduced. It means that $2 in create_class is ID_TK, but the method
itself requires second parameter to be of type tree of class "e" but not
of class "x" (identifier_node).  Could you explain what I'm missing and
where $2 becomes a tree?
Thanks.
        Sergiy Zhenochin.