return failure();

  SmallVector<OpAsmParser::Argument> packed_args;
  for (auto argAndType : llvm::zip(region_args, region_arg_types)) {
    auto& arg = packed_args.emplace_back();
    arg.ssaName = std::get<0>(argAndType);
    arg.type = std::get<1>(argAndType);
  }
  if (parser.parseRegion(body, packed_args)) return failure();

  // Add derived `operandSegmentSizes` attribute based on parsed operands.