# HG changeset patch
# Parent  8d78cd7c4a9e5e73d7f3f935a393b32cfed507a4
Issue #27364: Deprecate invalid unicode escape sequences

diff -r 8d78cd7c4a9e Lib/test/test_unicode.py
--- a/Lib/test/test_unicode.py	Sun Jun 26 00:09:19 2016 +0300
+++ b/Lib/test/test_unicode.py	Mon Jun 27 01:29:17 2016 +0000
@@ -2729,6 +2729,10 @@
         support.check_free_after_iterating(self, iter, str)
         support.check_free_after_iterating(self, reversed, str)
 
+    def test_invalid_sequences(self):
+        for letter in "deghijklmopqswyzABCDEFGHIJKLMOPQRSTVWXYZ":
+            with self.assertWarns(DeprecationWarning):
+                eval(r"'\%s'" % letter)
 
 class StringModuleTest(unittest.TestCase):
     def test_formatter_parser(self):
diff -r 8d78cd7c4a9e Objects/unicodeobject.c
--- a/Objects/unicodeobject.c	Sun Jun 26 00:09:19 2016 +0300
+++ b/Objects/unicodeobject.c	Mon Jun 27 01:29:17 2016 +0000
@@ -6022,6 +6022,11 @@
                 goto error;
             }
             else {
+                /* Deprecate invalid escape sequences */
+                if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                                    "invalid escape sequence '%c'", c) < 0) {
+                    goto onError;
+                }
                 WRITECHAR('\\');
                 WRITECHAR((unsigned char)s[-1]);
             }