From 4c6a6d5ac7aa348d5b4b9a4d6bb7cc18af49f72a Mon Sep 17 00:00:00 2001
From: Jonathan Davis <jonathandavis4@users.noreply.github.com>
Date: Thu, 29 Jul 2021 06:04:56 +0100
Subject: [PATCH] Fixed #23895 -- Prevented pickling of ResolverMatch.

Pickling a ResolverMatch did not work correctly in many cases,
especially with CBVs and URLResolvers in the list of tried URL paths.
---
 AUTHORS                            | 1 +
 django/urls/resolvers.py           | 4 ++++
 tests/urlpatterns_reverse/tests.py | 7 +++++++
 3 files changed, 12 insertions(+)

diff --git a/AUTHORS b/AUTHORS
index 0b7dd6ad72..3a8df03ca3 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -478,6 +478,7 @@ answer newbie questions, and generally made Django that much better:
     Jökull Sólberg Auðunsson <jokullsolberg@gmail.com>
     Jon Dufresne <jon.dufresne@gmail.com>
     Jonas Haag <jonas@lophus.org>
+    Jonathan Davis <jonathandavis47780@gmail.com>
     Jonatas C. D. <jonatas.cd@gmail.com>
     Jonathan Buchanan <jonathan.buchanan@gmail.com>
     Jonathan Daugherty (cygnus) <http://www.cprogrammer.org/>
diff --git a/django/urls/resolvers.py b/django/urls/resolvers.py
index 3a53bce1de..6ea18dd22f 100644
--- a/django/urls/resolvers.py
+++ b/django/urls/resolvers.py
@@ -10,6 +10,7 @@ import inspect
 import re
 import string
 from importlib import import_module
+from pickle import PicklingError
 from urllib.parse import quote
 
 from asgiref.local import Local
@@ -71,6 +72,9 @@ class ResolverMatch:
             )
         )
 
+    def __reduce_ex__(self, protocol):
+        raise PicklingError(f'Cannot pickle {self.__class__.__qualname__}.')
+
 
 def get_resolver(urlconf=None):
     if urlconf is None:
diff --git a/tests/urlpatterns_reverse/tests.py b/tests/urlpatterns_reverse/tests.py
index f2102c5304..332bc19e76 100644
--- a/tests/urlpatterns_reverse/tests.py
+++ b/tests/urlpatterns_reverse/tests.py
@@ -1,6 +1,7 @@
 """
 Unit tests for reverse URL lookups.
 """
+import pickle
 import sys
 import threading
 
@@ -1167,6 +1168,12 @@ class ResolverMatchTests(SimpleTestCase):
                     f"route='{name}/')",
                 )
 
+    @override_settings(ROOT_URLCONF='urlpatterns.path_urls')
+    def test_pickling(self):
+        msg = 'Cannot pickle ResolverMatch.'
+        with self.assertRaisesMessage(pickle.PicklingError, msg):
+            pickle.dumps(resolve('/users/'))
+
 
 @override_settings(ROOT_URLCONF='urlpatterns_reverse.erroneous_urls')
 class ErroneousViewTests(SimpleTestCase):