gh-116241: Add support of multiple inheritance with typing.NamedTuple

Doc/library/typing.rst

@@ -2401,6 +2401,9 @@ types.
  disallowed in Python 3.15. To create a NamedTuple class with 0 fields,
  use ``class NT(NamedTuple): pass`` or ``NT = NamedTuple("NT", [])``.
 
+ .. versionchanged:: 3.14
+ Added support for arbitrary multiple inheritance.
+
 .. class:: NewType(name, tp)
 
  Helper class to create low-overhead :ref:`distinct types <distinct>`.

Doc/whatsnew/3.14.rst

@@ -1803,6 +1803,11 @@ typing
 * Remove :class:`!typing.ByteString`. It had previously raised a
  :exc:`DeprecationWarning` since Python 3.12.
 
+* Add support of multiple inheritance with :class:`~typing.NamedTuple`.
+ Previously, multiple inheritance was only supported if there was exactly
+ one other base and the base was :class:`typing.Generic`.
+ (Contributed by Serhiy Storchaka in :gh:`116241`.)
+
 * :class:`typing.TypeAliasType` now supports star unpacking.
 
 urllib

Lib/test/test_typing.py

@@ -8003,7 +8003,40 @@ class X(NamedTuple):
 
  def test_multiple_inheritance(self):
  class A:
- pass
+ @property
+ def x(self):
+ return 4
+ @property
+ def y(self):
+ return 5
+ def __len__(self):
+ return 10
+
+ class X(NamedTuple, A):
+ x: int
+ self.assertEqual(X.__bases__, (tuple, A))
+ self.assertEqual(X.__orig_bases__, (NamedTuple, A))
+ self.assertEqual(X.__mro__, (X, tuple, A, object))
+
+ a = X(3)
+ self.assertEqual(a.x, 3)
+ self.assertEqual(a.y, 5)
+ self.assertEqual(len(a), 1)
+
+ class Y(A, NamedTuple):
+ x: int
+ self.assertEqual(Y.__bases__, (A, tuple))
+ self.assertEqual(Y.__orig_bases__, (A, NamedTuple))
+ self.assertEqual(Y.__mro__, (Y, A, tuple, object))
+
+ a = Y(3)
+ self.assertEqual(a.x, 3)
+ self.assertEqual(a.y, 5)
+ self.assertEqual(len(a), 10)
+
+ def test_multiple_inheritance_errors(self):
+ class A(NamedTuple):
+ x: int
  with self.assertRaises(TypeError):
  class X(NamedTuple, A):
  x: int

Lib/typing.py

@@ -2897,10 +2897,6 @@ def __new__(cls, typename, bases, ns):
  if "__classcell__" in ns:
  raise TypeError(
  "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(
- 'can only inherit from a NamedTuple type and Generic')
  bases = tuple(tuple if base is _NamedTuple else base for base in bases)
  if "__annotations__" in ns:
  types = ns["__annotations__"]

Misc/NEWS.d/next/Library/2022-04-28-18-45-58.gh-issue-116241.hu9kRk.rst

@@ -0,0 +1 @@
+Add support for arbitrary multiple inheritance with :class:`typing.NamedTuple`.