Merge pull request #3450 from YYun-D/slice_reduce

implement `reduce` method to `PySlice`

Lib/test/test_slice.py

@@ -234,8 +234,6 @@ class SliceTest(unittest.TestCase):
         x[1:2] = 42
         self.assertEqual(tmp, [(slice(1, 2), 42)])
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_pickle(self):
         s = slice(10, 20, 3)
         for protocol in (0,1,2):

vm/src/builtins/slice.rs

@@ -194,6 +194,20 @@ impl PySlice {
         let (start, stop, step) = self.inner_indices(length, vm)?;
         Ok(vm.new_tuple((start, stop, step)))
     }
+
+    #[allow(clippy::type_complexity)]
+    #[pymethod(magic)]
+    fn reduce(
+        zelf: PyRef<Self>,
+    ) -> PyResult<(
+        PyTypeRef,
+        (Option<PyObjectRef>, PyObjectRef, Option<PyObjectRef>),
+    )> {
+        Ok((
+            zelf.clone_class(),
+            (zelf.start.clone(), zelf.stop.clone(), zelf.step.clone()),
+        ))
+    }
 }
 
 impl Comparable for PySlice {