[3.9] bpo-34480: fix bug where match variable is used prior to being defined (GH-17643)

Lib/_markupbase.py

@@ -157,6 +157,7 @@ def parse_marked_section(self, i, report=1):
             match= _msmarkedsectionclose.search(rawdata, i+3)
         else:
             self.error('unknown status keyword %r in marked section' % rawdata[i+3:j])
+            match = None
         if not match:
             return -1
         if report:

Lib/test/test_htmlparser.py

@@ -787,5 +787,27 @@ def test_weird_chars_in_unquoted_attribute_values(self):
                             ('starttag', 'form',
                                 [('action', 'bogus|&#()value')])])
 
+    def test_invalid_keyword_error_exception(self):
+        # bpo-34480: check that subclasses that define an
+        # error method that raises an exception work
+        class InvalidMarkupException(Exception):
+            pass
+        class MyHTMLParser(html.parser.HTMLParser):
+            def error(self, message):
+                raise InvalidMarkupException(message)
+        parser = MyHTMLParser()
+        with self.assertRaises(InvalidMarkupException):
+            parser.feed('<![invalid>')
+
+    def test_invalid_keyword_error_pass(self):
+        # bpo-34480: check that subclasses that define an
+        # error method that doesn't raise an exception work
+        class MyHTMLParser(html.parser.HTMLParser):
+            def error(self, message):
+                pass
+        parser = MyHTMLParser()
+        self.assertEqual(parser.feed('<![invalid>'), None)
+
+
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Library/2022-04-09-11-28-49.bpo-34480.Pw-GJ6.rst

@@ -0,0 +1,3 @@
+Fix a bug where :mod:`_markupbase` raised an :exc:`UnboundLocalError`
+when an invalid keyword was found in marked section. Patch by Marek
+Suscak.