scriptfunction: Make sure we have valid __name__ and __qualname__ (pytorch#147906)

    It's not fully clear why these are not being created, but you can definitely
    reproduce this in code. `__name__` is fun, since there appears to be no way to
    explicitly set it on the pybind11 layer or c++ layer. I've set this in the
    python wrapper code (which works correctly). But let me know if people feel
    strongly and want us to go explicitly cast to python within the cpp functions
    and set it there.

Pull Request resolved: pytorch#147906
Approved by: https://github.com/jansel
ghstack dependencies: pytorch#147894

Author: c00w

test/test_jit.py

@@ -458,6 +458,13 @@ def fn(x: torch.Tensor) -> torch.Tensor:
 
             pkl_fn = pickle.dumps(fn, protocol=0)
 
+    def test_script_fn_valid_name(self):
+        @torch.jit.script
+        def fn(x: torch.Tensor) -> torch.Tensor:
+            return x
+        self.assertIsNotNone(fn.__name__)
+        self.assertIsNotNone(fn.__qualname__)
+
     def test_restore_device(self):
         class M(torch.jit.ScriptModule):
             def __init__(self, cpu_device_str):

torch/jit/_script.py

@@ -63,6 +63,8 @@
 Functionally equivalent to a :class:`ScriptModule`, but represents a single
 function and does not have any attributes or Parameters.
 """
+ScriptFunction.__name__ = "ScriptFunction"
+ScriptFunction.__qualname__ = "torch.jit.ScriptFunction"
 set_module(ScriptFunction, "torch.jit")
 
 
@@ -1214,6 +1216,8 @@ def _script_impl(
         )
         # Forward docstrings
         fn.__doc__ = obj.__doc__
+        fn.__name__ = "ScriptFunction"
+        fn.__qualname__ = "torch.jit.ScriptFunction"
         # Allow torch.compile() to inline
         fn._torchdynamo_inline = obj  # type: ignore[attr-defined]
         _set_jit_function_cache(obj, fn)