fix nf4 test that is failing in CI (#3216)

Author: vkuzo

torchao/dtypes/nf4tensor.py

@@ -1129,6 +1129,26 @@ def _(*args, **kwargs):
     return out
 
 
+@implements_torch_function(torch.Tensor.view_as)
+def function_view_as(*args, **kwargs):
+    """Handle view_as for NF4Tensor.
+
+    When view_as is called (typically by autograd internals), we need to return
+    a fresh NF4Tensor without autograd metadata to avoid conflicts.
+    """
+    tensor = args[0]
+
+    # Create a new NF4Tensor with detached inner tensors to avoid autograd conflicts
+    updated_attrs = {}
+    tensor_attrs, _ = tensor.__tensor_flatten__()
+    for attr in tensor_attrs:
+        inner_tensor = getattr(tensor, attr)
+        # Detach to create a fresh tensor without autograd metadata
+        updated_attrs[attr] = inner_tensor.detach()
+
+    return NF4Tensor(*construct_nf4_args(tensor, updated_attrs))
+
+
 @torch._dynamo.allow_in_graph
 def nf4_constructor(
     tensor_meta: SubclassTensorArgs,