bpo-45948: Remove constructor discrepancy in C version of ElementTree.XMLParser (GH-31152)

Both implementations accept target=None now.

Author: jacobtylerwalls

Lib/test/test_xml_etree.py

@@ -758,6 +758,15 @@ def end_ns(self, prefix):
  ('end-ns', ''),
  ])
 
+ def test_initialize_parser_without_target(self):
+ # Explicit None
+ parser = ET.XMLParser(target=None)
+ self.assertIsInstance(parser.target, ET.TreeBuilder)
+
+ # Implicit None
+ parser2 = ET.XMLParser()
+ self.assertIsInstance(parser2.target, ET.TreeBuilder)
+
  def test_children(self):
  # Test Element children iteration
 

Misc/NEWS.d/next/Library/2022-02-05-18-22-05.bpo-45948.w4mCnE.rst

@@ -0,0 +1,5 @@
+Fixed a discrepancy in the C implementation of the
+:mod:`xml.etree.ElementTree` module. Now, instantiating an
+:class:`xml.etree.ElementTree.XMLParser` with a ``target=None``
+keyword provides a default :class:`xml.etree.ElementTree.TreeBuilder`
+target as the Python implementation does.

Modules/_elementtree.c

@@ -3637,15 +3637,15 @@ ignore_attribute_error(PyObject *value)
 _elementtree.XMLParser.__init__
 
  *
- target: object = NULL
+ target: object = None
  encoding: str(accept={str, NoneType}) = None
 
 [clinic start generated code]*/
 
 static int
 _elementtree_XMLParser___init___impl(XMLParserObject *self, PyObject *target,
  const char *encoding)
-/*[clinic end generated code: output=3ae45ec6cdf344e4 input=53e35a829ae043e8]*/
+/*[clinic end generated code: output=3ae45ec6cdf344e4 input=7e716dd6e4f3e439]*/
 {
  self->entity = PyDict_New();
  if (!self->entity)
@@ -3670,7 +3670,7 @@ _elementtree_XMLParser___init___impl(XMLParserObject *self, PyObject *target,
  (unsigned long)_Py_HashSecret.expat.hashsalt);
  }
 
- if (target) {
+ if (target != Py_None) {
  Py_INCREF(target);
  } else {
  target = treebuilder_new(&TreeBuilder_Type, NULL, NULL);