nn.Identity is not required to be compatible with PyTorch < 1.1.0 as …

…the minimum PyTorch version we currently support is 1.10.0 (huggingface#25974)

nn.Identity is not required to be compatible with PyTorch < 1.1.0 as the
minimum PyTorch version we currently support is 1.10.0

src/transformers/modeling_utils.py

@@ -31,7 +31,7 @@
 import torch
 from packaging import version
 from torch import Tensor, nn
-from torch.nn import CrossEntropyLoss
+from torch.nn import CrossEntropyLoss, Identity
 
 from .activations import get_activation
 from .configuration_utils import PretrainedConfig
@@ -151,20 +151,6 @@ def no_init_weights(_enable=True):
         _init_weights = old_init_weights
 
 
-try:
-    from torch.nn import Identity
-except ImportError:
-    # Older PyTorch compatibility
-    class Identity(nn.Module):
-        r"""A placeholder identity operator that is argument-insensitive."""
-
-        def __init__(self, *args, **kwargs):
-            super().__init__()
-
-        def forward(self, input):
-            return input
-
-
 def get_parameter_device(parameter: Union[nn.Module, GenerationMixin, "ModuleUtilsMixin"]):
     try:
         return next(parameter.parameters()).device