Refs #30841 -- Made isnull lookup raise ValueError for non-boolean values.

Per deprecation timeline.

django/db/models/lookups.py

@@ -1,6 +1,5 @@
 import itertools
 import math
-import warnings
 from copy import copy
 
 from django.core.exceptions import EmptyResultSet
@@ -10,7 +9,6 @@ from django.db.models.fields import (
 )
 from django.db.models.query_utils import RegisterLookupMixin
 from django.utils.datastructures import OrderedSet
-from django.utils.deprecation import RemovedInDjango40Warning
 from django.utils.functional import cached_property
 from django.utils.hashable import make_hashable
 
@@ -508,15 +506,9 @@ class IsNull(BuiltinLookup):
 
     def as_sql(self, compiler, connection):
         if not isinstance(self.rhs, bool):
-            # When the deprecation ends, replace with:
-            # raise ValueError(
-            #     'The QuerySet value for an isnull lookup must be True or '
-            #     'False.'
-            # )
-            warnings.warn(
-                'Using a non-boolean value for an isnull lookup is '
-                'deprecated, use True or False instead.',
-                RemovedInDjango40Warning,
+            raise ValueError(
+                'The QuerySet value for an isnull lookup must be True or '
+                'False.'
             )
         sql, params = compiler.compile(self.lhs)
         if self.rhs:

docs/ref/models/querysets.txt

@@ -3424,11 +3424,6 @@ SQL equivalent:
 
     SELECT ... WHERE pub_date IS NULL;
 
-.. deprecated:: 3.1
-
-    Using non-boolean values as the right-hand side is deprecated, use ``True``
-    or ``False`` instead. In Django 4.0, the exception will be raised.
-
 .. fieldlookup:: regex
 
 ``regex``

docs/releases/4.0.txt

@@ -268,3 +268,6 @@ See :ref:`deprecated-features-3.1` for details on these changes, including how
 to remove usage of these features.
 
 * The ``PASSWORD_RESET_TIMEOUT_DAYS`` setting is removed.
+
+* The :lookup:`isnull` lookup no longer allows using non-boolean values as the
+  right-hand side.

tests/lookup/tests.py

@@ -9,7 +9,6 @@ from django.db.models import Exists, Max, OuterRef
 from django.db.models.functions import Substr
 from django.test import TestCase, skipUnlessDBFeature
 from django.test.utils import isolate_apps
-from django.utils.deprecation import RemovedInDjango40Warning
 
 from .models import (
     Article, Author, Freebie, Game, IsNullWithNoneAsRHS, Player, Season, Tag,
@@ -985,15 +984,7 @@ class LookupTests(TestCase):
         self.assertEqual(authors.get(), newest_author)
 
     def test_isnull_non_boolean_value(self):
-        # These tests will catch ValueError in Django 4.0 when using
-        # non-boolean values for an isnull lookup becomes forbidden.
-        # msg = (
-        #     'The QuerySet value for an isnull lookup must be True or False.'
-        # )
-        msg = (
-            'Using a non-boolean value for an isnull lookup is deprecated, '
-            'use True or False instead.'
-        )
+        msg = 'The QuerySet value for an isnull lookup must be True or False.'
         tests = [
             Author.objects.filter(alias__isnull=1),
             Article.objects.filter(author__isnull=1),
@@ -1002,5 +993,5 @@ class LookupTests(TestCase):
         ]
         for qs in tests:
             with self.subTest(qs=qs):
-                with self.assertWarnsMessage(RemovedInDjango40Warning, msg):
+                with self.assertRaisesMessage(ValueError, msg):
                     qs.exists()