bpo-32912: Revert SyntaxWarning on invalid escape sequences. (GH-15195)

DeprecationWarning will continue to be emitted for invalid escape
sequences in string and bytes literals just as it did in 3.7.

SyntaxWarning may be emitted in the future. But per mailing list
discussion, we don't yet know when because we haven't settled on how to
do so in a non-disruptive manner.

(Applies 4c5b6bac2408f879231c7cd38d67657dd4804e7c to the master branch).
(This is https://github.com/python/cpython/pull/15142 for master/3.9)


https://bugs.python.org/issue32912



Automerge-Triggered-By: @gpshead

1 files changed, 33 insertions, 4 deletions

diff --git a/Lib/test/test_string_literals.py b/Lib/test/test_string_literals.py
index 5961d59..0cea2ed 100644
--- a/Lib/test/test_string_literals.py
+++ b/Lib/test/test_string_literals.py
@@ -32,6 +32,7 @@ import sys
 import shutil
 import tempfile
 import unittest
+import warnings
 
 
 TEMPLATE = r"""# coding: %s
@@ -110,10 +111,24 @@ class TestLiterals(unittest.TestCase):
         for b in range(1, 128):
             if b in b"""\n\r"'01234567NU\\abfnrtuvx""":
                 continue
-            with self.assertWarns(SyntaxWarning):
+            with self.assertWarns(DeprecationWarning):
                 self.assertEqual(eval(r"'\%c'" % b), '\\' + chr(b))
 
-        self.check_syntax_warning("'''\n\\z'''")
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter('always', category=DeprecationWarning)
+            eval("'''\n\\z'''")
+        self.assertEqual(len(w), 1)
+        self.assertEqual(w[0].filename, '<string>')
+        self.assertEqual(w[0].lineno, 1)
+
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter('error', category=DeprecationWarning)
+            with self.assertRaises(SyntaxError) as cm:
+                eval("'''\n\\z'''")
+            exc = cm.exception
+        self.assertEqual(w, [])
+        self.assertEqual(exc.filename, '<string>')
+        self.assertEqual(exc.lineno, 1)
 
     def test_eval_str_raw(self):
         self.assertEqual(eval(""" r'x' """), 'x')
@@ -145,10 +160,24 @@ class TestLiterals(unittest.TestCase):
         for b in range(1, 128):
             if b in b"""\n\r"'01234567\\abfnrtvx""":
                 continue
-            with self.assertWarns(SyntaxWarning):
+            with self.assertWarns(DeprecationWarning):
                 self.assertEqual(eval(r"b'\%c'" % b), b'\\' + bytes([b]))
 
-        self.check_syntax_warning("b'''\n\\z'''")
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter('always', category=DeprecationWarning)
+            eval("b'''\n\\z'''")
+        self.assertEqual(len(w), 1)
+        self.assertEqual(w[0].filename, '<string>')
+        self.assertEqual(w[0].lineno, 1)
+
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter('error', category=DeprecationWarning)
+            with self.assertRaises(SyntaxError) as cm:
+                eval("b'''\n\\z'''")
+            exc = cm.exception
+        self.assertEqual(w, [])
+        self.assertEqual(exc.filename, '<string>')
+        self.assertEqual(exc.lineno, 1)
 
     def test_eval_bytes_raw(self):
         self.assertEqual(eval(""" br'x' """), b'x')