message: NFC: Add AbstractOperation as a friend of 'Op'.
  This allows for accessing the hidden overload of 'Op::hasTrait'.
diff: @@ -897,6 +897,9 @@ private:
  return llvm::is_contained(llvm::makeArrayRef({ClassID::getID<Traits>()...}),
  traitID);
  }
  +
  + /// Allow access to 'hasTrait'.
  + friend AbstractOperation;
  };
  // These functions are out-of-line implementations of the methods in BinaryOp,
  