[GitHub] [arrow] westonpace opened a new issue, #36792: [C++] Serializing to Substrait does not include all field names if there is a list with structs

["westonpace (via GitHub)" <gi...@apache.org>]

westonpace opened a new issue, #36792:
URL: https://github.com/apache/arrow/issues/36792

   ### Describe the bug, including details regarding any error messages, version, and platform.
   
   Currently field names are figured out using this method:
   
   ```
   void ToProtoGetDepthFirstNames(const FieldVector& fields,
                                  google::protobuf::RepeatedPtrField<std::string>* names) {
     for (const auto& field : fields) {
       *names->Add() = field->name();
   
       if (field->type()->id() == Type::STRUCT) {
         ToProtoGetDepthFirstNames(field->type()->fields(), names);
       }
     }
   }
   ```
   
   If there is a list / large list / map (dictionary? extension?) that has children then their names will not be included in the result.
   
   For example, given the schema:
   
   ```
     auto schema = arrow::schema(
         {arrow::field("preceding_field", arrow::int32()),
          arrow::field("points",
                       arrow::list(arrow::field(
                           "point", arrow::struct_(
                                        {arrow::field("x", arrow::float64()),
                                         arrow::field("y", arrow::float64())})))),
          arrow::field("trailing_field", arrow::int32())});
   ```
   
   I would expect the names to be `["preceding_field", "points", "x", "y", "trailing_field"]` but I only get `["preceding_field", "points", "trailing_field"]`.
   
   ### Component(s)
   
   C++


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