Fix wrong is_namedtuple implementation

src/accelerate/utils/operations.py

@@ -64,17 +64,10 @@ def is_tensor_information(tensor_info):
 
 def is_namedtuple(data):
     """
-    Checks if `x` is a `namedtuple` or not. Can have false positives, but only if a user is trying to mimic a
+    Checks if `data` is a `namedtuple` or not. Can have false positives, but only if a user is trying to mimic a
     `namedtuple` perfectly.
     """
-    data_type = type(data)
-    bases = data_type.__bases__
-    if len(bases) != 1 or bases[0] != tuple:
-        return False
-    fields = getattr(data_type, "_fields", None)
-    if not isinstance(fields, tuple):
-        return False
-    return all(isinstance(member, str) for member in fields)
+    return isinstance(data, tuple) and hasattr(data, "_asdict") and hasattr(data, "_fields")
 
 
 def honor_type(obj, generator):

tests/test_utils.py

@@ -17,6 +17,7 @@
 import unittest
 import warnings
 from collections import UserDict, namedtuple
+from typing import NamedTuple, Optional
 from unittest.mock import Mock, patch
 
 import torch
@@ -40,6 +41,7 @@
     save,
     send_to_device,
 )
+from accelerate.utils.operations import is_namedtuple
 
 
 ExampleNamedTuple = namedtuple("ExampleNamedTuple", "a b c")
@@ -310,3 +312,25 @@ def test_send_to_device_compiles(self):
     def test_convert_to_fp32(self):
         compiled_convert_to_fp32 = torch.compile(convert_to_fp32, fullgraph=True)
         compiled_convert_to_fp32(torch.zeros([1], dtype=torch.bfloat16))
+
+    def test_named_tuples(self):
+        class QuantTensorBase(NamedTuple):
+            value: torch.Tensor
+            scale: Optional[torch.Tensor]
+            zero_point: Optional[torch.Tensor]
+
+        class Second(QuantTensorBase):
+            pass
+
+        a = QuantTensorBase(torch.tensor(1.0), None, None)
+        b = Second(torch.tensor(1.0), None, None)
+
+        point = namedtuple("Point", ["x", "y"])
+        p = point(11, y=22)
+
+        self.assertTrue(is_namedtuple(a))
+        self.assertTrue(is_namedtuple(b))
+        self.assertTrue(is_namedtuple(p))
+        self.assertFalse(is_namedtuple((1, 2)))
+        self.assertFalse(is_namedtuple("hey"))
+        self.assertFalse(is_namedtuple(object()))