Specifically ignore empty slices

asttokens/mark_tokens.py

@@ -83,7 +83,9 @@ def _visit_after_children(self, node, parent_token, token):
     last = None
     for child in cast(Callable, self._iter_children)(node):
       # astroid slices have especially wrong positions, we don't want them to corrupt their parents.
-      if not first or child.first_token.index < first.index and not util.is_astroid_slice(child):
+      if util.is_empty_astroid_slice(child):
+        continue
+      if not first or child.first_token.index < first.index:
         first = child.first_token
       if not last or child.last_token.index > last.index:
         last = child.last_token

asttokens/util.py

@@ -228,9 +228,13 @@ def is_slice(node):
   )
 
 
-def is_astroid_slice(node):
+def is_empty_astroid_slice(node):
   # type: (AstNode) -> bool
-  return is_slice(node) and not isinstance(node, ast.AST)
+  return (
+      node.__class__.__name__ == "Slice"
+      and not isinstance(node, ast.AST)
+      and node.lower is node.upper is node.step
+  )
 
 
 # Sentinel value used by visit_tree().

tests/test_mark_tokens.py

@@ -235,7 +235,7 @@ def test_deep_recursion(self):
 
   def test_slices(self):
     # Make sure we don't fail on parsing slices of the form `foo[4:]`.
-    source = "(foo.Area_Code, str(foo.Phone)[:3], str(foo.Phone)[3:], foo[:], bar[::2, :], [a[:]][::-1])"
+    source = "(foo.Area_Code, str(foo.Phone)[:3], str(foo.Phone)[3:], foo[:], bar[::2, :], bar2[:, ::2], [a[:]][::-1])"
     m = self.create_mark_checker(source)
     self.assertIn("Tuple:" + source, m.view_nodes_at(1, 0))
     self.assertEqual(m.view_nodes_at(1, 1),