Add method.__self__ attribute

Lib/test/test_copy.py

@@ -887,8 +887,6 @@ class TestCopy(unittest.TestCase):
         del d
         self.assertEqual(len(v), 1)
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_deepcopy_bound_method(self):
         class Foo(object):
             def m(self):

Lib/test/test_functools.py

@@ -543,8 +543,6 @@ class TestPartialMethod(unittest.TestCase):
 
         self.assertEqual(self.A.over_partial(self.a, 5, d=8), ((self.a, 7, 5), {'c': 6, 'd': 8}))
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_bound_method_introspection(self):
         obj = self.a
         self.assertIs(obj.both.__self__, obj)

Lib/test/test_tokenize.py

@@ -1325,8 +1325,6 @@ class TestDetectEncoding(TestCase):
             self.assertEqual(fp.encoding, 'utf-8-sig')
             self.assertEqual(fp.mode, 'r')
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_filename_in_exception(self):
         # When possible, include the file name in the exception.
         path = 'some_file_path'

vm/src/builtins/function.rs

@@ -473,6 +473,11 @@ impl PyBoundMethod {
         self.function.clone()
     }
 
+    #[pyproperty(name = "__self__")]
+    fn get_self(&self) -> PyObjectRef {
+        self.object.clone()
+    }
+
     #[pyproperty(magic)]
     fn module(&self, vm: &VirtualMachine) -> Option<PyObjectRef> {
         vm.get_attribute(self.function.clone(), "__module__").ok()