anchor.diff:            (when (and (include-field field)
                        (not (skip-field field)))
               (multiple-value-bind (tags deserializers nslot rslot oneof-slot)
  -                (generate-field-deserializer message field vbuf vidx :raw-p raw-p)
  +                (generate-field-deserializer message field vbuf vidx)
                 (assert tags)
                 (assert deserializers)
                 (loop for tag in tags
  
positive.code:             (t nil)))))
  
  (defun generate-non-repeated-field-deserializer
      (class index lazy-p vbuf vidx dest &key raw-p)
    "Returns two values: The first is lisp code that deserializes the specified object
  to dest and updates vidx to the new index. The second is the tag of this field.
  
  
negative.code:   CONSTRUCTOR: The constructor to use when making the object.
    MISSING-VALUE: The value to set a field to if not found while deserializing.
    SKIP-FIELDS: Fields to skip while deserializing.
    INCLUDE-FIELDS: Fields to include while deserializing."
    (let ((vbuf (gensym "BUFFER"))
          (vidx (gensym "INDEX"))
          (vlim (gensym "LIMIT"))
  