From 448d974d9646b96806ef07a9ceeceb96e4bac645 Mon Sep 17 00:00:00 2001
From: Nick Pope <nick@nickpope.me.uk>
Date: Thu, 8 Jul 2021 00:19:35 +0100
Subject: [PATCH] Fixed #32499 -- Escaped additional metacharacters in
 simplify_regex().

---
 django/contrib/admindocs/utils.py |  2 +-
 tests/admin_docs/test_views.py    | 43 +++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/django/contrib/admindocs/utils.py b/django/contrib/admindocs/utils.py
index 1dc30a39604..b836d17fd15 100644
--- a/django/contrib/admindocs/utils.py
+++ b/django/contrib/admindocs/utils.py
@@ -145,7 +145,7 @@ unnamed_group_matcher = _lazy_re_compile(r'\(')
 def replace_metacharacters(pattern):
     """Remove unescaped metacharacters from the pattern."""
     return re.sub(
-        r'((?:^|(?<!\\))(?:\\\\)*)(\\?)([?^$])',
+        r'((?:^|(?<!\\))(?:\\\\)*)(\\?)([?*+^$]|\\[bBAZ])',
         lambda m: m[1] + m[3] if m[2] else m[1],
         pattern,
     )
diff --git a/tests/admin_docs/test_views.py b/tests/admin_docs/test_views.py
index bf11ae5be59..5355382dfaf 100644
--- a/tests/admin_docs/test_views.py
+++ b/tests/admin_docs/test_views.py
@@ -407,8 +407,28 @@ class AdminDocViewFunctionsTests(SimpleTestCase):
             (r'a?', '/a'),
             (r'a??', '/a'),
             (r'a???', '/a'),
+            (r'a*', '/a'),
+            (r'a**', '/a'),
+            (r'a***', '/a'),
+            (r'a+', '/a'),
+            (r'a++', '/a'),
+            (r'a+++', '/a'),
+            (r'\Aa', '/a'),
+            (r'\A\Aa', '/a'),
+            (r'\A\A\Aa', '/a'),
+            (r'a\Z', '/a'),
+            (r'a\Z\Z', '/a'),
+            (r'a\Z\Z\Z', '/a'),
+            (r'\ba', '/a'),
+            (r'\b\ba', '/a'),
+            (r'\b\b\ba', '/a'),
+            (r'a\B', '/a'),
+            (r'a\B\B', '/a'),
+            (r'a\B\B\B', '/a'),
             # Multiple mixed metacharacters.
             (r'^a/?$', '/a/'),
+            (r'\Aa\Z', '/a'),
+            (r'\ba\B', '/a'),
             # Escaped single metacharacters.
             (r'\^a', r'/^a'),
             (r'\\^a', r'/\\a'),
@@ -425,6 +445,26 @@ class AdminDocViewFunctionsTests(SimpleTestCase):
             (r'a\\\?', r'/a\\?'),
             (r'a\\\\?', r'/a\\\\'),
             (r'a\\\\\?', r'/a\\\\?'),
+            (r'a\*', r'/a*'),
+            (r'a\\*', r'/a\\'),
+            (r'a\\\*', r'/a\\*'),
+            (r'a\\\\*', r'/a\\\\'),
+            (r'a\\\\\*', r'/a\\\\*'),
+            (r'a\+', r'/a+'),
+            (r'a\\+', r'/a\\'),
+            (r'a\\\+', r'/a\\+'),
+            (r'a\\\\+', r'/a\\\\'),
+            (r'a\\\\\+', r'/a\\\\+'),
+            (r'\\Aa', r'/\Aa'),
+            (r'\\\Aa', r'/\\a'),
+            (r'\\\\Aa', r'/\\\Aa'),
+            (r'\\\\\Aa', r'/\\\\a'),
+            (r'\\\\\\Aa', r'/\\\\\Aa'),
+            (r'a\\Z', r'/a\Z'),
+            (r'a\\\Z', r'/a\\'),
+            (r'a\\\\Z', r'/a\\\Z'),
+            (r'a\\\\\Z', r'/a\\\\'),
+            (r'a\\\\\\Z', r'/a\\\\\Z'),
             # Escaped mixed metacharacters.
             (r'^a\?$', r'/a?'),
             (r'^a\\?$', r'/a\\'),
@@ -437,6 +477,9 @@ class AdminDocViewFunctionsTests(SimpleTestCase):
             (r'^a\\\?\\\$', r'/a\\?\\$'),
             (r'^a\\\\?\\\\$', r'/a\\\\\\\\'),
             (r'^a\\\\\?\\\\\$', r'/a\\\\?\\\\$'),
+            # Complex examples with metacharacters and (un)named groups.
+            (r'^\b(?P<slug>\w+)\B/(\w+)?', '/<slug>/<var>'),
+            (r'^\A(?P<slug>\w+)\Z', '/<slug>'),
         )
         for pattern, output in tests:
             with self.subTest(pattern=pattern):