pythongh-92123: Convert _elementtree types to heap types (python#99221)

Author: erlend-aasland

Lib/test/test_xml_etree_c.py

@@ -181,6 +181,26 @@ def __hash__(self):
         r = e.get(X())
         self.assertIsNone(r)
 
+    @support.cpython_only
+    def test_immutable_types(self):
+        root = cET.fromstring('<a></a>')
+        dataset = (
+            cET.Element,
+            cET.TreeBuilder,
+            cET.XMLParser,
+            type(root.iter()),
+        )
+        for tp in dataset:
+            with self.subTest(tp=tp):
+                with self.assertRaisesRegex(TypeError, "immutable"):
+                    tp.foo = 1
+
+    @support.cpython_only
+    def test_disallow_instantiation(self):
+        root = cET.fromstring('<a></a>')
+        iter_type = type(root.iter())
+        support.check_disallow_instantiation(self, iter_type)
+
 
 @unittest.skipUnless(cET, 'requires _elementtree')
 class TestAliasWorking(unittest.TestCase):

Misc/NEWS.d/next/Library/2020-11-20-21-06-08.bpo-40077.M-iZq3.rst

@@ -0,0 +1 @@
+Convert :mod:`elementtree` types to heap types. Patch by Erlend E. Aasland.