message: Fix another compile error on mac
  Summary:
  Pull Request resolved:
  Fix the error from
diff: @@ -18,7 +18,6 @@ class ClassChecker {
  ClassChecker(ClassChecker&& other) = default;
  ClassChecker& operator=(const ClassChecker&) = delete;
  - ClassChecker& operator=(ClassChecker&& rhs) = default;
  void run(const Scope& scope);
  