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

Doc/library/typing.rst

@@ -2389,6 +2389,9 @@ 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

@@ -574,6 +574,11 @@ 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`.)
+
 urllib
 ------
 

Lib/test/test_typing.py

@@ -7925,7 +7925,40 @@ 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

@@ -2952,10 +2952,6 @@ def annotate(format):
 class NamedTupleMeta(type):
     def __new__(cls, typename, bases, ns):
         assert _NamedTuple in bases
-        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`.