[BugFix] Same behaviour in compiled and non-compiled versions of _new_unsafe

tensordict/_td.py

@@ -314,7 +314,9 @@ def _new_unsafe(
         nested: bool = True,
         **kwargs: dict[str, Any] | None,
     ) -> TensorDict:
-        if is_compiling():
+        if is_compiling() and cls is TensorDict:
+            # If the cls is not TensorDict, we must escape this to keep the same class.
+            # That's unfortunate because as of now it graph breaks but that's the best we can do.
             return TensorDict(
                 source,
                 batch_size=batch_size,

test/test_compile.py

@@ -587,6 +587,29 @@ def locked_op(tc):
         tc_op_c = locked_op_c(data)
         assert (tc_op == tc_op_c).all()
 
+    def test_td_new_unsafe(self, mode):
+
+        class MyTd(TensorDict):
+            pass
+
+        def func_td():
+            return TensorDict._new_unsafe(a=torch.randn(3), batch_size=torch.Size(()))
+
+        @torch.compile(fullgraph=True, mode=mode)
+        def func_c_td():
+            return TensorDict._new_unsafe(a=torch.randn(3), batch_size=torch.Size(()))
+
+        def func_mytd():
+            return MyTd._new_unsafe(a=torch.randn(3), batch_size=torch.Size(()))
+
+        # This will graph break
+        @torch.compile(mode=mode)
+        def func_c_mytd():
+            return MyTd._new_unsafe(a=torch.randn(3), batch_size=torch.Size(()))
+
+        assert type(func_td()) is type(func_c_td())
+        assert type(func_mytd()) is type(func_c_mytd())
+
 
 @pytest.mark.skipif(
     TORCH_VERSION < version.parse("2.4.0"), reason="requires torch>=2.4"