bpo-43102: Set namedtuple __new__'s internal builtins to a dict. (GH-24439) (GH-24452)

Author: miss-islington

Lib/collections/__init__.py

@@ -424,7 +424,7 @@ def namedtuple(typename, field_names, *, rename=False, defaults=None, module=Non
 
     namespace = {
         '_tuple_new': tuple_new,
-        '__builtins__': None,
+        '__builtins__': {},
         '__name__': f'namedtuple_{typename}',
     }
     code = f'lambda _cls, {arg_list}: _tuple_new(_cls, ({arg_list}))'

Lib/test/test_collections.py

@@ -680,6 +680,11 @@ class NewPoint(tuple):
         self.assertEqual(np.x, 1)
         self.assertEqual(np.y, 2)
 
+    def test_new_builtins_issue_43102(self):
+        self.assertEqual(
+            namedtuple('C', ()).__new__.__globals__['__builtins__'],
+            {})
+
 
 ################################################################################
 ### Abstract Base Classes

Misc/NEWS.d/next/Library/2021-02-03-22-55-27.bpo-43102.TSlZ6J.rst

@@ -0,0 +1,2 @@
+The namedtuple __new__ method had its __builtins__ set to None instead
+of an actual dictionary.  This created problems for introspection tools.