Fixed #22356 -- Added a check to make sure unique_together fields are local.

django/db/models/base.py

@@ -1346,6 +1346,19 @@ class Model(six.with_metaclass(ModelBase)):
                             id='models.E013',
                         )
                     )
+                elif field not in cls._meta.local_fields:
+                    errors.append(
+                        checks.Error(
+                            ("'%s' refers to field '%s' which is not local "
+                             "to model '%s'.") % (
+                                option, field_name, cls._meta.object_name
+                            ),
+                            hint=("This issue may be caused by multi-table "
+                                  "inheritance."),
+                            obj=cls,
+                            id='models.E016',
+                        )
+                    )
         return errors
 
     @classmethod

docs/ref/checks.txt

@@ -44,6 +44,7 @@ Models
 * **models.E013**: ``index_together/unique_together`` refers to a ManyToManyField ``<field name>``, but ManyToManyFields are not supported for that option.
 * **models.E014**: ``ordering`` must be a tuple or list (even if you want to order by only one field).
 * **models.E015**: ``ordering`` refers to the non-existent field ``<field name>``.
+* **models.E016**: ``index_together/unique_together`` refers to field ``<field_name>`` which is not local to model ``<model>``.
 
 Fields
 ~~~~~~

tests/invalid_models_tests/test_models.py

@@ -76,6 +76,30 @@ class IndexTogetherTests(IsolatedModelsTestCase):
         ]
         self.assertEqual(errors, expected)
 
+    def test_pointing_to_non_local_field(self):
+        class Foo(models.Model):
+            field1 = models.IntegerField()
+
+        class Bar(Foo):
+            field2 = models.IntegerField()
+
+            class Meta:
+                index_together = [
+                    ["field2", "field1"],
+                ]
+
+        errors = Bar.check()
+        expected = [
+            Error(
+                ("'index_together' refers to field 'field1' which is not "
+                 "local to model 'Bar'."),
+                hint=("This issue may be caused by multi-table inheritance."),
+                obj=Bar,
+                id='models.E016',
+            ),
+        ]
+        self.assertEqual(errors, expected)
+
     def test_pointing_to_m2m_field(self):
         class Model(models.Model):
             m2m = models.ManyToManyField('self')