Fixed #30621 -- Fixed crash of __contains lookup for Date/DateTimeRangeField when the right hand side is the same type.

Thanks Tilman Koschnick for the report and initial patch.
Thanks Carlton Gibson the review.

Regression in 6b048b364ca1e0e56a0d3815bf2be33ac9998355.

6 files changed, 76 insertions, 3 deletions

diff --git a/django/contrib/postgres/fields/ranges.py b/django/contrib/postgres/fields/ranges.py
index 74ba4eb230..0e8a347d5f 100644
--- a/django/contrib/postgres/fields/ranges.py
+++ b/django/contrib/postgres/fields/ranges.py
@@ -170,7 +170,12 @@ class DateTimeRangeContains(models.Lookup):
         params = lhs_params + rhs_params
         # Cast the rhs if needed.
         cast_sql = ''
-        if isinstance(self.rhs, models.Expression) and self.rhs._output_field_or_none:
+        if (
+            isinstance(self.rhs, models.Expression) and
+            self.rhs._output_field_or_none and
+            # Skip cast if rhs has a matching range type.
+            not isinstance(self.rhs._output_field_or_none, self.lhs.output_field.__class__)
+        ):
             cast_internal_type = self.lhs.output_field.base_field.get_internal_type()
             cast_sql = '::{}'.format(connection.data_types.get(cast_internal_type))
         return '%s @> %s%s' % (lhs, rhs, cast_sql), params
diff --git a/docs/releases/2.2.4.txt b/docs/releases/2.2.4.txt
index a1a849680d..0ad92f4ab1 100644
--- a/docs/releases/2.2.4.txt
+++ b/docs/releases/2.2.4.txt
@@ -12,3 +12,9 @@ Bugfixes
 * Fixed a regression in Django 2.2 when ordering a ``QuerySet.union()``,
   ``intersection()``, or ``difference()`` by a field type present more than
   once results in the wrong ordering being used (:ticket:`30628`).
+
+* Fixed a migration crash on PostgreSQL when adding a check constraint
+  with a ``contains`` lookup on
+  :class:`~django.contrib.postgres.fields.DateRangeField` or
+  :class:`~django.contrib.postgres.fields.DateTimeRangeField`, if the right
+  hand side of an expression is the same type (:ticket:`30621`).
diff --git a/tests/postgres_tests/migrations/0002_create_test_models.py b/tests/postgres_tests/migrations/0002_create_test_models.py
index dc941de139..b9f9cee6bf 100644
--- a/tests/postgres_tests/migrations/0002_create_test_models.py
+++ b/tests/postgres_tests/migrations/0002_create_test_models.py
@@ -211,7 +211,9 @@ class Migration(migrations.Migration):
                 ('bigints', BigIntegerRangeField(null=True, blank=True)),
                 ('decimals', DecimalRangeField(null=True, blank=True)),
                 ('timestamps', DateTimeRangeField(null=True, blank=True)),
+                ('timestamps_inner', DateTimeRangeField(null=True, blank=True)),
                 ('dates', DateRangeField(null=True, blank=True)),
+                ('dates_inner', DateRangeField(null=True, blank=True)),
             ],
             options={
                 'required_db_vendor': 'postgresql'
diff --git a/tests/postgres_tests/models.py b/tests/postgres_tests/models.py
index 2bb6e6fcdf..3d170a9a1a 100644
--- a/tests/postgres_tests/models.py
+++ b/tests/postgres_tests/models.py
@@ -135,7 +135,9 @@ class RangesModel(PostgreSQLModel):
     bigints = BigIntegerRangeField(blank=True, null=True)
     decimals = DecimalRangeField(blank=True, null=True)
     timestamps = DateTimeRangeField(blank=True, null=True)
+    timestamps_inner = DateTimeRangeField(blank=True, null=True)
     dates = DateRangeField(blank=True, null=True)
+    dates_inner = DateRangeField(blank=True, null=True)
 
 
 class RangeLookupsModel(PostgreSQLModel):
diff --git a/tests/postgres_tests/test_constraints.py b/tests/postgres_tests/test_constraints.py
index 0e09a1c546..2fc6ee5322 100644
--- a/tests/postgres_tests/test_constraints.py
+++ b/tests/postgres_tests/test_constraints.py
@@ -1,5 +1,7 @@
+import datetime
+
 from django.db import connection, transaction
-from django.db.models import Q
+from django.db.models import F, Q
 from django.db.models.constraints import CheckConstraint
 from django.db.utils import IntegrityError
 
@@ -33,3 +35,51 @@ class SchemaTests(PostgreSQLTestCase):
         with self.assertRaises(IntegrityError), transaction.atomic():
             RangesModel.objects.create(ints=(20, 50))
         RangesModel.objects.create(ints=(10, 30))
+
+    def test_check_constraint_daterange_contains(self):
+        constraint_name = 'dates_contains'
+        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
+        constraint = CheckConstraint(
+            check=Q(dates__contains=F('dates_inner')),
+            name=constraint_name,
+        )
+        with connection.schema_editor() as editor:
+            editor.add_constraint(RangesModel, constraint)
+        with connection.cursor() as cursor:
+            constraints = connection.introspection.get_constraints(cursor, RangesModel._meta.db_table)
+        self.assertIn(constraint_name, constraints)
+        date_1 = datetime.date(2016, 1, 1)
+        date_2 = datetime.date(2016, 1, 4)
+        with self.assertRaises(IntegrityError), transaction.atomic():
+            RangesModel.objects.create(
+                dates=(date_1, date_2),
+                dates_inner=(date_1, date_2.replace(day=5)),
+            )
+        RangesModel.objects.create(
+            dates=(date_1, date_2),
+            dates_inner=(date_1, date_2),
+        )
+
+    def test_check_constraint_datetimerange_contains(self):
+        constraint_name = 'timestamps_contains'
+        self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
+        constraint = CheckConstraint(
+            check=Q(timestamps__contains=F('timestamps_inner')),
+            name=constraint_name,
+        )
+        with connection.schema_editor() as editor:
+            editor.add_constraint(RangesModel, constraint)
+        with connection.cursor() as cursor:
+            constraints = connection.introspection.get_constraints(cursor, RangesModel._meta.db_table)
+        self.assertIn(constraint_name, constraints)
+        datetime_1 = datetime.datetime(2016, 1, 1)
+        datetime_2 = datetime.datetime(2016, 1, 2, 12)
+        with self.assertRaises(IntegrityError), transaction.atomic():
+            RangesModel.objects.create(
+                timestamps=(datetime_1, datetime_2),
+                timestamps_inner=(datetime_1, datetime_2.replace(hour=13)),
+            )
+        RangesModel.objects.create(
+            timestamps=(datetime_1, datetime_2),
+            timestamps_inner=(datetime_1, datetime_2),
+        )
diff --git a/tests/postgres_tests/test_ranges.py b/tests/postgres_tests/test_ranges.py
index ae834b6ff0..89f32ee77c 100644
--- a/tests/postgres_tests/test_ranges.py
+++ b/tests/postgres_tests/test_ranges.py
@@ -115,11 +115,15 @@ class TestRangeContainsLookup(PostgreSQLTestCase):
         ]
         cls.obj = RangesModel.objects.create(
             dates=(cls.dates[0], cls.dates[3]),
+            dates_inner=(cls.dates[1], cls.dates[2]),
             timestamps=(cls.timestamps[0], cls.timestamps[3]),
+            timestamps_inner=(cls.timestamps[1], cls.timestamps[2]),
         )
         cls.aware_obj = RangesModel.objects.create(
             dates=(cls.dates[0], cls.dates[3]),
+            dates_inner=(cls.dates[1], cls.dates[2]),
             timestamps=(cls.aware_timestamps[0], cls.aware_timestamps[3]),
+            timestamps_inner=(cls.timestamps[1], cls.timestamps[2]),
         )
         # Objects that don't match any queries.
         for i in range(3, 4):
@@ -140,6 +144,7 @@ class TestRangeContainsLookup(PostgreSQLTestCase):
             (self.aware_timestamps[1], self.aware_timestamps[2]),
             Value(self.dates[0], output_field=DateTimeField()),
             Func(F('dates'), function='lower', output_field=DateTimeField()),
+            F('timestamps_inner'),
         )
         for filter_arg in filter_args:
             with self.subTest(filter_arg=filter_arg):
@@ -154,6 +159,7 @@ class TestRangeContainsLookup(PostgreSQLTestCase):
             (self.dates[1], self.dates[2]),
             Value(self.dates[0], output_field=DateField()),
             Func(F('timestamps'), function='lower', output_field=DateField()),
+            F('dates_inner'),
         )
         for filter_arg in filter_args:
             with self.subTest(filter_arg=filter_arg):
@@ -361,7 +367,9 @@ class TestSerialization(PostgreSQLSimpleTestCase):
         '\\"bounds\\": \\"[)\\"}", "decimals": "{\\"empty\\": true}", '
         '"bigints": null, "timestamps": "{\\"upper\\": \\"2014-02-02T12:12:12+00:00\\", '
         '\\"lower\\": \\"2014-01-01T00:00:00+00:00\\", \\"bounds\\": \\"[)\\"}", '
-        '"dates": "{\\"upper\\": \\"2014-02-02\\", \\"lower\\": \\"2014-01-01\\", \\"bounds\\": \\"[)\\"}" }, '
+        '"timestamps_inner": null, '
+        '"dates": "{\\"upper\\": \\"2014-02-02\\", \\"lower\\": \\"2014-01-01\\", \\"bounds\\": \\"[)\\"}", '
+        '"dates_inner": null }, '
         '"model": "postgres_tests.rangesmodel", "pk": null}]'
     )