JIT not compatible with PyTorch/XLA (#3743)

src/transformers/activations.py

+import logging
 import math
 
 import torch
 import torch.nn.functional as F
 
 
+logger = logging.getLogger(__name__)
+
+
 def swish(x):
     return x * torch.sigmoid(x)
 
@@ -29,7 +33,15 @@ if torch.__version__ < "1.4.0":
     gelu = _gelu_python
 else:
     gelu = F.gelu
-    gelu_new = torch.jit.script(gelu_new)
+    try:
+        import torch_xla  # noqa F401
+
+        logger.warning(
+            "The torch_xla package was detected in the python environment. PyTorch/XLA and JIT is untested,"
+            " no activation function will be traced with JIT."
+        )
+    except ImportError:
+        gelu_new = torch.jit.script(gelu_new)
 
 ACT2FN = {
     "relu": F.relu,