remove old comments, add test

Author: matiaslindgren

pandas/core/indexing.py

@@ -811,9 +811,6 @@ def _maybe_mask_setitem_value(self, indexer, value):
                 if is_scalar_indexer(icols, self.ndim - 1) and ndim == 1:
                     # e.g. test_loc_setitem_boolean_mask_allfalse
                     if len(newkey) == 0:
-                        # FIXME: kludge for test_loc_setitem_boolean_mask_allfalse
-                        # TODO(GH#45333): may be fixed when deprecation is enforced
-
                         value = value.iloc[:0]
                     else:
                         # test_loc_setitem_ndframe_values_alignment
@@ -834,9 +831,6 @@ def _maybe_mask_setitem_value(self, indexer, value):
 
                     elif ndim == 2 and value.shape[1] == 1:
                         if len(newkey) == 0:
-                            # FIXME: kludge for
-                            #  test_loc_setitem_all_false_boolean_two_blocks
-                            #  TODO(GH#45333): may be fixed when deprecation is enforced
                             value = value.iloc[:0]
                         else:
                             # test_loc_setitem_ndframe_values_alignment

pandas/tests/indexing/test_loc.py

@@ -3264,3 +3264,8 @@ def test_loc_nonunique_masked_index(self):
             index=Index(np.array(ids).repeat(1000), dtype="Int64"),
         )
         tm.assert_frame_equal(result, expected)
+
+    def test_loc_assign_to_should_not_raise(self):
+        # GH 57735
+        df = DataFrame(index=[1, 1, 2, 2], data=["1", "1", "2", "2"])
+        df.loc[df[0].str.len() > 1, 0] = df[0]