[6.0.x] Fixed #36903 -- Fixed further NameErrors when inspecting functions with deferred annotations.

Provide a wrapper for safe introspection of user functions on Python 3.14+.

Follow-up to 601914722956cc41f1f2c53972d669ddee6ffc04.
Backport of 56ed37e17e5b1a509aa68a0c797dcff34fcc1366 from main.

7 files changed, 128 insertions, 0 deletions

diff --git a/tests/auth_tests/test_auth_backends.py b/tests/auth_tests/test_auth_backends.py
index 0ba169249b..3ea6ff6a69 100644
--- a/tests/auth_tests/test_auth_backends.py
+++ b/tests/auth_tests/test_auth_backends.py
@@ -1,5 +1,7 @@
 import sys
+import unittest
 from datetime import date
+from typing import TYPE_CHECKING
 from unittest import mock
 from unittest.mock import patch
 
@@ -30,6 +32,7 @@ from django.test import (
     override_settings,
 )
 from django.urls import reverse
+from django.utils.version import PY314
 from django.views.debug import ExceptionReporter, technical_500_response
 from django.views.decorators.debug import sensitive_variables
 
@@ -41,6 +44,10 @@ from .models import (
     UUIDUser,
 )
 
+if TYPE_CHECKING:
+    type AnnotatedUsername = str
+    type AnnotatedPassword = str
+
 
 class FilteredExceptionReporter(ExceptionReporter):
     def get_traceback_frames(self):
@@ -1285,6 +1292,29 @@ class AuthenticateTests(TestCase):
     def test_skips_backends_with_decorated_method(self):
         self.assertEqual(authenticate(username="test", password="test"), self.user1)
 
+    @unittest.skipUnless(PY314, "Deferred annotations are Python 3.14+ only")
+    @override_settings(
+        AUTHENTICATION_BACKENDS=[
+            "auth_tests.test_auth_backends.AnnotatedBackend",
+        ],
+    )
+    def test_backend_uses_deferred_annotations(self):
+        class AnnotatedBackend:
+            invariant_user = self.user1
+
+            def authenticate(
+                self,
+                request: HttpRequest,
+                username: AnnotatedUsername,
+                password: AnnotatedPassword,
+            ) -> User | None:
+                return self.invariant_user
+
+        with unittest.mock.patch(
+            "django.contrib.auth.import_string", return_value=AnnotatedBackend
+        ):
+            self.assertEqual(authenticate(username="test", password="test"), self.user1)
+
 
 class ImproperlyConfiguredUserModelTest(TestCase):
     """
diff --git a/tests/check_framework/test_security.py b/tests/check_framework/test_security.py
index d5cc8a9ad6..0f03845c15 100644
--- a/tests/check_framework/test_security.py
+++ b/tests/check_framework/test_security.py
@@ -1,4 +1,6 @@
 import itertools
+import unittest
+from typing import TYPE_CHECKING
 
 from django.conf import settings
 from django.core.checks.messages import Error, Warning
@@ -6,8 +8,12 @@ from django.core.checks.security import base, csrf, sessions
 from django.core.management.utils import get_random_secret_key
 from django.test import SimpleTestCase
 from django.test.utils import override_settings
+from django.utils.version import PY314
 from django.views.generic import View
 
+if TYPE_CHECKING:
+    from django.http.request import HttpRequest
+
 
 class CheckSessionCookieSecureTest(SimpleTestCase):
     @override_settings(
@@ -613,6 +619,12 @@ def failure_view_with_invalid_signature():
     pass
 
 
+if PY314:
+
+    def failure_view_with_deferred_annotations(request: HttpRequest, reason: str):
+        pass
+
+
 good_class_based_csrf_failure_view = View.as_view()
 
 
@@ -653,6 +665,15 @@ class CSRFFailureViewTest(SimpleTestCase):
     def test_failure_view_valid_class_based(self):
         self.assertEqual(csrf.check_csrf_failure_view(None), [])
 
+    @unittest.skipUnless(PY314, "Deferred annotations are Python 3.14+ only")
+    @override_settings(
+        CSRF_FAILURE_VIEW=(
+            "check_framework.test_security.failure_view_with_deferred_annotations"
+        ),
+    )
+    def test_failure_view_valid_deferred_annotations(self):
+        self.assertEqual(csrf.check_csrf_failure_view(None), [])
+
 
 class CheckCrossOriginOpenerPolicyTest(SimpleTestCase):
     @override_settings(
diff --git a/tests/check_framework/test_urls.py b/tests/check_framework/test_urls.py
index a3b219f3a4..5164fe7671 100644
--- a/tests/check_framework/test_urls.py
+++ b/tests/check_framework/test_urls.py
@@ -1,3 +1,5 @@
+import unittest
+
 from django.conf import settings
 from django.core.checks.messages import Error, Warning
 from django.core.checks.urls import (
@@ -10,6 +12,7 @@ from django.core.checks.urls import (
 )
 from django.test import SimpleTestCase
 from django.test.utils import override_settings
+from django.utils.version import PY314
 
 
 class CheckUrlConfigTests(SimpleTestCase):
@@ -323,6 +326,14 @@ class CheckCustomErrorHandlersTests(SimpleTestCase):
         result = check_custom_error_handlers(None)
         self.assertEqual(result, [])
 
+    @unittest.skipUnless(PY314, "Deferred annotations are Python 3.14+ only")
+    @override_settings(
+        ROOT_URLCONF="check_framework.urls.good_error_handler_deferred_annotations",
+    )
+    def test_good_function_based_handlers_deferred_annotations(self):
+        result = check_custom_error_handlers(None)
+        self.assertEqual(result, [])
+
     @override_settings(
         ROOT_URLCONF="check_framework.urls.good_class_based_error_handlers",
     )
diff --git a/tests/check_framework/urls/good_error_handler_deferred_annotations.py b/tests/check_framework/urls/good_error_handler_deferred_annotations.py
new file mode 100644
index 0000000000..8b4ead5566
--- /dev/null
+++ b/tests/check_framework/urls/good_error_handler_deferred_annotations.py
@@ -0,0 +1,15 @@
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from django.http.request import HttpRequest
+
+urlpatterns = []
+
+handler400 = __name__ + ".good_handler_deferred_annotations"
+handler403 = __name__ + ".good_handler_deferred_annotations"
+handler404 = __name__ + ".good_handler_deferred_annotations"
+handler500 = __name__ + ".good_handler_deferred_annotations"
+
+
+def good_handler_deferred_annotations(request: HttpRequest, exception=None):
+    pass
diff --git a/tests/deprecation/test_deprecate_posargs.py b/tests/deprecation/test_deprecate_posargs.py
index 166fe5dd69..8c70d5d205 100644
--- a/tests/deprecation/test_deprecate_posargs.py
+++ b/tests/deprecation/test_deprecate_posargs.py
@@ -1,7 +1,13 @@
 import inspect
+import unittest
+from typing import TYPE_CHECKING
 
 from django.test import SimpleTestCase
 from django.utils.deprecation import RemovedAfterNextVersionWarning, deprecate_posargs
+from django.utils.version import PY314
+
+if TYPE_CHECKING:
+    type AnnotatedKwarg = int
 
 
 class DeprecatePosargsTests(SimpleTestCase):
@@ -355,6 +361,17 @@ class DeprecatePosargsTests(SimpleTestCase):
             def func(*args, b=1):
                 return args, b
 
+    @unittest.skipUnless(PY314, "Deferred annotations are Python 3.14+ only")
+    def test_decorator_rejects_var_positional_param_with_deferred_annotation(self):
+        with self.assertRaisesMessage(
+            TypeError,
+            "@deprecate_posargs() cannot be used with variable positional `*args`.",
+        ):
+
+            @deprecate_posargs(RemovedAfterNextVersionWarning, ["b"])
+            def func(*args, b: AnnotatedKwarg = 1):
+                return args, b
+
     def test_decorator_does_not_apply_to_class(self):
         with self.assertRaisesMessage(
             TypeError,
diff --git a/tests/expressions/tests.py b/tests/expressions/tests.py
index 981d84e9e8..c058c6e275 100644
--- a/tests/expressions/tests.py
+++ b/tests/expressions/tests.py
@@ -5,6 +5,7 @@ import uuid
 from collections import namedtuple
 from copy import deepcopy
 from decimal import Decimal
+from typing import TYPE_CHECKING
 from unittest import mock
 
 from django.core.exceptions import FieldError
@@ -77,6 +78,7 @@ from django.test.utils import (
     register_lookup,
 )
 from django.utils.functional import SimpleLazyObject
+from django.utils.version import PY314
 
 from .models import (
     UUID,
@@ -94,6 +96,9 @@ from .models import (
     Time,
 )
 
+if TYPE_CHECKING:
+    type AnnotatedKwarg = str
+
 
 class BasicExpressionsTests(TestCase):
     @classmethod
@@ -1589,6 +1594,14 @@ class SimpleExpressionTests(SimpleTestCase):
         replaced = expression.replace_expressions({"replacement": Expression()})
         self.assertEqual(replaced.get_source_expressions(), [falsey])
 
+    @unittest.skipUnless(PY314, "Deferred annotations are Python 3.14+ only")
+    def test_expression_signature_uses_deferred_annotations(self):
+        class AnnotatedExpression(Expression):
+            def __init__(self, *args, my_kw: AnnotatedKwarg, **kwargs):
+                super().__init__(*args, **kwargs)
+
+        self.assertEqual(AnnotatedExpression(my_kw=""), AnnotatedExpression(my_kw=""))
+
 
 class ExpressionsNumericTests(TestCase):
     @classmethod
diff --git a/tests/template_tests/tests.py b/tests/template_tests/tests.py
index 7364c7ca64..573fd9db2e 100644
--- a/tests/template_tests/tests.py
+++ b/tests/template_tests/tests.py
@@ -1,10 +1,16 @@
 import sys
+import unittest
+from typing import TYPE_CHECKING
 
 from django.template import Context, Engine, TemplateDoesNotExist, TemplateSyntaxError
 from django.template.base import UNKNOWN_SOURCE
 from django.test import SimpleTestCase, override_settings
 from django.urls import NoReverseMatch
 from django.utils import translation
+from django.utils.version import PY314
+
+if TYPE_CHECKING:
+    type AnnotatedKwarg = str
 
 
 class TemplateTestMixin:
@@ -221,6 +227,21 @@ class TemplateTestMixin:
         template = self._engine().from_string("{{ description.count }}")
         self.assertEqual(template.render(Context({"description": "test"})), "")
 
+    @unittest.skipUnless(PY314, "Deferred annotations are Python 3.14+ only")
+    def test_callable_uses_deferred_annotations(self):
+        """
+        Missing required arguments are gracefully handled when a signature uses
+        deferred annotations.
+        """
+
+        class MyObject:
+            @staticmethod
+            def uses_deferred_annotations(value: AnnotatedKwarg):
+                return value
+
+        template = self._engine().from_string("{{ obj.uses_deferred_annotations }}")
+        self.assertEqual(template.render(Context({"obj": MyObject()})), "")
+
 
 class TemplateTests(TemplateTestMixin, SimpleTestCase):
     debug_engine = False