Raise a clear error message when __classcell__ is seen in typing.NamedTuple subclasses

Author: johnslavik

Doc/library/typing.rst

@@ -2359,6 +2359,10 @@ types.
        # A functional syntax is also supported
        Employee = NamedTuple('Employee', [('name', str), ('id', int)])
 
+   .. note::
+      Using :func:`super` (and the ``__class__`` :term:`closure variable`) in methods of ``NamedTuple`` subclasses
+      is unsupported and causes a :class:`RuntimeError`.
+
    .. versionchanged:: 3.6
       Added support for :pep:`526` variable annotation syntax.
 

Lib/test/test_typing.py

@@ -8359,6 +8359,23 @@ class VeryAnnoying(metaclass=Meta): pass
             class Foo(NamedTuple):
                 attr = very_annoying
 
+    def test_super_explicitly_disallowed(self):
+        expected_message = (
+            "uses of super() and __class__ are unsupported "
+            "in methods of NamedTuple subclasses"
+        )
+
+        with self.assertRaises(RuntimeError, msg=expected_message):
+            class ThisWontWork(NamedTuple):
+                def __repr__(self):
+                    return super().__repr__()
+
+        with self.assertRaises(RuntimeError, msg=expected_message):
+            class ThisWontWorkEither(NamedTuple):
+                @property
+                def name(self):
+                    return __class__.__name__
+
 
 class TypedDictTests(BaseTestCase):
     def test_basics_functional_syntax(self):

Lib/typing.py

@@ -2961,6 +2961,9 @@ def annotate(format):
 class NamedTupleMeta(type):
     def __new__(cls, typename, bases, ns):
         assert _NamedTuple in bases
+        if "__classcell__" in ns:
+            raise RuntimeError(
+                "uses of super() and __class__ are unsupported in methods of NamedTuple subclasses")
         for base in bases:
             if base is not _NamedTuple and base is not Generic:
                 raise TypeError(

Misc/NEWS.d/next/Library/2025-02-13-15-10-56.gh-issue-85795.jeXXI9.rst

@@ -0,0 +1,3 @@
+Using :func:`super` and ``__class__`` :term:`closure variable` in
+user-defined methods of :class:`typing.NamedTuple` subclasses is now
+explicitly prevented at runtime.