Given an IDL defined in the namespace mongo (i.e. set to global.cpp_namespace) that defines a customer type with the serializer/deserializer functions in a nested namespace (e.g., mongo::util), the generated code doesn't take into account the specified namespace for the serializer/deserializer functions, causing a symbol not found error at compiling time.

More in details, given the following IDL:

global:
    cpp_namespace: "mongo"
...

types:
    status:
        bson_serialization_type: any
        cpp_type: "mongo::Status"
        serializer: "mongo::util::serializeStatusToBSON"
        deserializer: "mongo::util::deserializeStatusFromBSON"
...

structs:
    CoordinatorMetadata
    ...
    fields:
        error:
            type: status

The compiler generates the following code:

namespace mongo {
...

void CoordinatorMetadata::serialize(BSONObjBuilder* builder) const {
...
    if (_error) {
        serializeStatusToBSON((*_error), kErrorFieldName, builder);
    }
...
}}

The problem is that the function serializeStatusToBSON is defined in the namespace mongo::util, not in mongo.