message: Use `this->` to access inherited member from dependent type (Fix GCC7 build, NFC)
diff: @@ -170,7 +170,7 @@ public:
  }
  /// Utility for easy access to the storage instance.
  - ImplType *getImpl() const { return static_cast<ImplType *>(type); }
  + ImplType *getImpl() const { return static_cast<ImplType *>(this->type); }
  };
  using ImplType = TypeStorage;
  