Method clearMetaData

bolt/expression/Expr.cpp:210–221

    std::unordered_set<FieldReference*>& multiplyReferencedFields,
    const std::vector<FieldReference*>& moreFields) {
  for (auto* newField : moreFields) {
    if (isMember(distinctFields, *newField)) {
      multiplyReferencedFields.insert(newField);
    } else {
      distinctFields.emplace_back(newField);
    }
  }
}

void Expr::computeDistinctFields() {
  for (auto& input : inputs_) {
    mergeFields(
        distinctFields_, multiplyReferencedFields_, input->distinctFields_);
  }
}