Fix validate_input_col for nn.Module or Callable (#96213)

Forward fix the problem introduced in pytorch/pytorch#95067

Not all `Callable` objects have `__name__` implemented. Using `repr` as the backup solution to get function name or reference.
Pull Request resolved: pytorch/pytorch#96213
Approved by: https://github.com/NivekT

test/test_datapipe.py

@@ -30,6 +30,7 @@
 import numpy as np
 
 import torch
+import torch.nn as nn
 import torch.utils.data.datapipes as dp
 import torch.utils.data.graph
 import torch.utils.data.graph_settings
@@ -663,6 +664,16 @@ def _mod_3_test(x):
 lambda_fn3 = lambda x: x >= 5  # noqa: E731
 
 
+class Add1Module(nn.Module):
+    def forward(self, x):
+        return x + 1
+
+
+class Add1Callable:
+    def __call__(self, x):
+        return x + 1
+
+
 class TestFunctionalIterDataPipe(TestCase):
 
     def _serialization_test_helper(self, datapipe, use_dill):
@@ -1326,6 +1337,10 @@ def _helper(ref_fn, fn, input_col=None, output_col=None, error=None):
         _helper(lambda data: (str(data[0]), data[1], data[2]), str, 0)
         _helper(lambda data: (data[0], data[1], int(data[2])), int, 2)
 
+        # Handle nn.Module and Callable (without __name__ implemented)
+        _helper(lambda data: (data[0] + 1, data[1], data[2]), Add1Module(), 0)
+        _helper(lambda data: (data[0] + 1, data[1], data[2]), Add1Callable(), 0)
+
     @suppress_warnings  # Suppress warning for lambda fn
     def test_map_dict_with_col_iterdatapipe(self):
         def fn_11(d):

torch/utils/data/datapipes/utils/common.py

@@ -78,9 +78,9 @@ def validate_input_col(fn: Callable, input_col: Optional[Union[int, tuple, list]
             continue
 
     if isinstance(fn, functools.partial):
-        fn_name = fn.func.__name__
+        fn_name = getattr(fn.func, "__name__", repr(fn.func))
     else:
-        fn_name = fn.__name__
+        fn_name = getattr(fn, "__name__", repr(fn))
 
     if len(non_default_kw_only) > 0:
         raise ValueError(