Use ast.Constant instead of ast.Str.

vulture/core.py

@@ -518,11 +518,11 @@ def visit_BinOp(self, node):
         "%(my_var)s" % locals()
         """
         if (
-            isinstance(node.left, ast.Str)
+            utils.is_ast_string(node.left)
             and isinstance(node.op, ast.Mod)
             and self._is_locals_call(node.right)
         ):
-            self.used_names |= set(re.findall(r"%\((\w+)\)", node.left.s))
+            self.used_names |= set(re.findall(r"%\((\w+)\)", node.left.value))
 
     def visit_Call(self, node):
         # Count getattr/hasattr(x, "some_attr", ...) as usage of some_attr.
@@ -531,21 +531,21 @@ def visit_Call(self, node):
             or (node.func.id == "hasattr" and len(node.args) == 2)
         ):
             attr_name_arg = node.args[1]
-            if isinstance(attr_name_arg, ast.Str):
-                self.used_names.add(attr_name_arg.s)
+            if utils.is_ast_string(attr_name_arg):
+                self.used_names.add(attr_name_arg.value)
 
         # Parse variable names in new format strings:
         # "{my_var}".format(**locals())
         if (
             isinstance(node.func, ast.Attribute)
-            and isinstance(node.func.value, ast.Str)
+            and utils.is_ast_string(node.func.value)
             and node.func.attr == "format"
             and any(
                 kw.arg is None and self._is_locals_call(kw.value)
                 for kw in node.keywords
             )
         ):
-            self._handle_new_format_string(node.func.value.s)
+            self._handle_new_format_string(node.func.value.value)
 
     def _handle_new_format_string(self, s):
         def is_identifier(name):
@@ -651,8 +651,8 @@ def visit_Assign(self, node):
         if _assigns_special_variable__all__(node):
             assert isinstance(node.value, (ast.List, ast.Tuple))
             for elt in node.value.elts:
-                if isinstance(elt, ast.Str):
-                    self.used_names.add(elt.s)
+                if utils.is_ast_string(elt):
+                    self.used_names.add(elt.value)
 
     def visit_While(self, node):
         self._handle_conditional_node(node, "while")

vulture/utils.py

@@ -53,6 +53,11 @@ def condition_is_always_true(condition):
     return _safe_eval(condition, False)
 
 
+def is_ast_string(node):
+    print("DIR", node, dir(node))
+    return isinstance(node, ast.Constant) and isinstance(node.value, str)
+
+
 def format_path(path):
     try:
         return path.relative_to(pathlib.Path.cwd())