Addressed PR comments

Lib/test/test_sax.py

@@ -13,7 +13,7 @@
                              XMLFilterBase, prepare_input_source
 from xml.sax.expatreader import create_parser
 from xml.sax.handler import (feature_namespaces, feature_external_ges,
-                             LexicalHandler)
+                             LexicalHandler, feature_namespace_prefixes)
 from xml.sax.xmlreader import InputSource, AttributesImpl, AttributesNSImpl
 from xml import sax
 from io import BytesIO, StringIO
@@ -1319,15 +1319,36 @@ def startElementNS(self, name, qname, attrs):
             ("<E />", "E"),
         ):
             parser = create_parser()
-            parser.setFeature(handler.feature_namespaces, 1)
-            parser.setFeature(handler.feature_namespace_prefixes, 1)
+            parser.setFeature(feature_namespaces, 1)
+            parser.setFeature(feature_namespace_prefixes, 1)
 
             h = Handler()
 
             parser.setContentHandler(h)
             parser.parse(StringIO(xml_s))
             self.assertEqual(h.qname, expected_qname)
 
+    def test_qualified_names_when_feature_not_set(self):
+
+        class Handler(ContentHandler):
+            def startElementNS(self, name, qname, attrs):
+                self.qname = qname
+
+        for xml_s in (
+                "<Q:E xmlns:Q='http://example.org/testuri'/>",
+                "<E xmlns='http://example.org/testuri'/>",
+                "<E />",
+        ):
+            parser = create_parser()
+            parser.setFeature(feature_namespaces, 1)
+
+            h = Handler()
+
+            parser.setContentHandler(h)
+            parser.parse(StringIO(xml_s))
+
+            self.assertIsNone(h.qname)
+
 
 # ===========================================================================
 #

Lib/xml/sax/expatreader.py

@@ -79,7 +79,7 @@ def getSystemId(self):
 class ExpatParser(xmlreader.IncrementalParser, xmlreader.Locator):
     """SAX driver for the pyexpat C module."""
 
-    def __init__(self, namespaceHandling=0, namespacePrefixesHandling=0, bufsize=2**16-20):
+    def __init__(self, namespaceHandling=0, bufsize=2**16-20):
         xmlreader.IncrementalParser.__init__(self, bufsize)
         self._source = xmlreader.InputSource()
         self._parser = None
@@ -89,7 +89,7 @@ def __init__(self, namespaceHandling=0, namespacePrefixesHandling=0, bufsize=2**
         self._entity_stack = []
         self._external_ges = 0
         self._interning = None
-        self._namespace_prefixes = namespacePrefixesHandling
+        self._namespace_prefixes = 0
 
     # XMLReader methods
 
@@ -147,8 +147,6 @@ def setFeature(self, name, state):
                     self._interning = {}
             else:
                 self._interning = None
-        elif name == feature_namespace_prefixes:
-            self._namespace_prefixes = state
         elif name == feature_validation:
             if state:
                 raise SAXNotSupportedException(
@@ -157,6 +155,8 @@ def setFeature(self, name, state):
             if state:
                 raise SAXNotSupportedException(
                     "expat does not read external parameter entities")
+        elif name == feature_namespace_prefixes:
+            self._namespace_prefixes = state
         else:
             raise SAXNotRecognizedException(
                 "Feature '%s' not recognized" % name)
@@ -375,6 +375,9 @@ def start_element_ns(self, name, attrs):
             newattrs[apair] = value
             qnames[apair] = qname
 
+        if not self._namespace_prefixes:
+            elem_qname = None
+
         self._cont_handler.startElementNS(pair, elem_qname,
                                           AttributesNSImpl(newattrs, qnames))