  
  class ParkingLot2(Place):
      # In lieu of any other connector, an existing OneToOneField will be
      # promoted to the primary key.
      parent = models.OneToOneField(Place)
  
  
  class ParkingLot3(Place):
      # The parent_link connector need not be the pk on the model.
      primary_key = models.AutoField(primary_key=True)
 
</s> remove     parent = models.OneToOneField(Place, parent_link=True)
 </s> add     parent = models.OneToOneField(Place, models.CASCADE, parent_link=True) </s> remove     parent = models.OneToOneField(Place, parent_link=True)
 </s> add     parent = models.OneToOneField(Place, models.CASCADE, parent_link=True) </s> remove     poll = models.ForeignKey(Poll, verbose_name="the related poll")
 </s> add     poll = models.ForeignKey(
        Poll,
        on_delete=models.CASCADE,
        verbose_name="the related poll",
    ) </s> remove         company_that_makes_it = models.ForeignKey(Manufacturer)
 </s> add         company_that_makes_it = models.ForeignKey(
            Manufacturer,
            on_delete=models.CASCADE,
        )
    parent = models.OneToOneField(Place, models.CASCADE)
  
  class ParkingLot2(Place):
      # In lieu of any other connector, an existing OneToOneField will be
      # promoted to the primary key.
    parent = models.OneToOneField(Place, models.CASCADE)
  
  
  class ParkingLot3(Place):
      # The parent_link connector need not be the pk on the model.
      primary_key = models.AutoField(primary_key=True)
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/model_inheritance_regress/models.py