Fixed #27648 -- Deprecated (iLmsu) regex groups in url() patterns.

1 files changed, 11 insertions, 4 deletions

diff --git a/django/utils/regex_helper.py b/django/utils/regex_helper.py
index 622d822759..d046b71d96 100644
--- a/django/utils/regex_helper.py
+++ b/django/utils/regex_helper.py
@@ -7,7 +7,10 @@ should be good enough for a large class of URLS, however.
 """
 from __future__ import unicode_literals
 
+import warnings
+
 from django.utils import six
+from django.utils.deprecation import RemovedInDjango21Warning
 from django.utils.six.moves import zip
 
 # Mapping of an escape character to a representative of that class. So, e.g.,
@@ -59,9 +62,7 @@ def normalize(pattern):
     (3) Select the first (essentially an arbitrary) element from any character
         class. Select an arbitrary character for any unordered class (e.g. '.'
         or '\w') in the pattern.
-    (4) Ignore comments, look-ahead and look-behind assertions, and any of the
-        reg-exp flags that won't change what we construct ("iLmsu"). "(?x)" is
-        an error, however.
+    (4) Ignore look-ahead and look-behind assertions.
     (5) Raise an error on any disjunctive ('|') constructs.
 
     Django's URLs for forward resolving are either all positional arguments or
@@ -128,10 +129,16 @@ def normalize(pattern):
                     walk_to_end(ch, pattern_iter)
                 else:
                     ch, escaped = next(pattern_iter)
-                    if ch in "iLmsu#!=<":
+                    if ch in '!=<':
                         # All of these are ignorable. Walk to the end of the
                         # group.
                         walk_to_end(ch, pattern_iter)
+                    elif ch in 'iLmsu#':
+                        warnings.warn(
+                            'Using (?%s) in url() patterns is deprecated.' % ch,
+                            RemovedInDjango21Warning
+                        )
+                        walk_to_end(ch, pattern_iter)
                     elif ch == ':':
                         # Non-capturing group
                         non_capturing_groups.append(len(result))