fix __parametesr__

Author: youknowone

Lib/test/test_typing.py

@@ -6106,8 +6106,6 @@ class C(Generic[T]): pass
         self.assertIs(get_origin((*tuple[*Ts],)[0]), tuple)
         self.assertIs(get_origin(Unpack[Tuple[Unpack[Ts]]]), Unpack)
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_get_args(self):
         T = TypeVar('T')
         class C(Generic[T]): pass

vm/src/stdlib/builtins.rs

@@ -1009,7 +1009,9 @@ mod builtins {
         {
             if let Some(type_params_tuple) = type_params.downcast_ref::<PyTuple>() {
                 if !type_params_tuple.is_empty() {
-                    class.set_attr(identifier!(vm, __type_params__), type_params, vm)?;
+                    class.set_attr(identifier!(vm, __type_params__), type_params.clone(), vm)?;
+                    // Also set __parameters__ for compatibility with typing module
+                    class.set_attr(identifier!(vm, __parameters__), type_params, vm)?;
                 }
             }
         }