message: Qualify string in OpDefinitionsGen. NFC.
diff: @@ -227,7 +227,7 @@ void OpMethodSignature::writeDefTo(raw_ostream &os,
  // initializers. This is incorrect for initializer list with more than one
  // element. Change to a more robust approach.
  auto removeParamDefaultValue = [](StringRef params) {
  - string result;
  + std::string result;
  std::pair<StringRef, StringRef> parts;
  while (!params.empty()) {
  parts = params.split("=");
  