3 files changed, 42 insertions, 12 deletions
diff --git a/django/db/models/deletion.py b/django/db/models/deletion.py
index 730847ef21..d8bb8f2e66 100644
--- a/django/db/models/deletion.py
+++ b/django/db/models/deletion.py
@@ -154,9 +154,10 @@ class Collector(object):
 
         model = new_objs[0].__class__
 
-        # Recursively collect parent models, but not their related objects.
-        # These will be found by meta.get_all_related_objects()
-        for parent_model, ptr in model._meta.parents.iteritems():
+        # Recursively collect concrete model's parent models, but not their
+        # related objects. These will be found by meta.get_all_related_objects()
+        concrete_model = model._meta.concrete_model
+        for ptr in concrete_model._meta.parents.itervalues():
             if ptr:
                 parent_objs = [getattr(obj, ptr.name) for obj in new_objs]
                 self.collect(parent_objs, source=model,
diff --git a/tests/modeltests/proxy_model_inheritance/models.py b/tests/modeltests/proxy_model_inheritance/models.py
index e69de29bb2..ef9ac6b0d3 100644
--- a/tests/modeltests/proxy_model_inheritance/models.py
+++ b/tests/modeltests/proxy_model_inheritance/models.py
@@ -0,0 +1,13 @@
+
+from django.db import models
+
+
+class ConcreteModel(models.Model):
+    pass
+
+class ConcreteModelSubclass(ConcreteModel):
+    pass
+
+class ConcreteModelSubclassProxy(ConcreteModelSubclass):
+    class Meta:
+        proxy = True
diff --git a/tests/modeltests/proxy_model_inheritance/tests.py b/tests/modeltests/proxy_model_inheritance/tests.py
index ae5ab20b5f..061cdc7e91 100644
--- a/tests/modeltests/proxy_model_inheritance/tests.py
+++ b/tests/modeltests/proxy_model_inheritance/tests.py
@@ -1,11 +1,3 @@
-"""
-XX. Proxy model inheritance
-
-Proxy model inheritance across apps can result in syncdb not creating the table
-for the proxied model (as described in #12286).  This test creates two dummy
-apps and calls syncdb, then verifies that the table has been created.
-"""
-
 from __future__ import absolute_import
 
 import os
@@ -14,12 +6,20 @@ import sys
 from django.conf import settings
 from django.core.management import call_command
 from django.db.models.loading import cache, load_app
-from django.test import TransactionTestCase
+from django.test import TestCase, TransactionTestCase
 from django.test.utils import override_settings
 
+from .models import (ConcreteModel, ConcreteModelSubclass,
+    ConcreteModelSubclassProxy)
+
 
 @override_settings(INSTALLED_APPS=('app1', 'app2'))
 class ProxyModelInheritanceTests(TransactionTestCase):
+    """
+    Proxy model inheritance across apps can result in syncdb not creating the table
+    for the proxied model (as described in #12286).  This test creates two dummy
+    apps and calls syncdb, then verifies that the table has been created.
+    """
 
     def setUp(self):
         self.old_sys_path = sys.path[:]
@@ -41,3 +41,19 @@ class ProxyModelInheritanceTests(TransactionTestCase):
         from .app2.models import NiceModel
         self.assertEqual(NiceModel.objects.all().count(), 0)
         self.assertEqual(ProxyModel.objects.all().count(), 0)
+
+
+class MultiTableInheritanceProxyTest(TestCase):
+
+    def test_model_subclass_proxy(self):
+        """
+        Deleting an instance of a model proxying a multi-table inherited
+        subclass should cascade delete down the whole inheritance chain (see
+        #18083).
+
+        """
+        instance = ConcreteModelSubclassProxy.objects.create()
+        instance.delete()
+        self.assertEqual(0, ConcreteModelSubclassProxy.objects.count())
+        self.assertEqual(0, ConcreteModelSubclass.objects.count())
+        self.assertEqual(0, ConcreteModel.objects.count())