namespace parameter { \
template <> \
class FieldEntry<EnumClass> : public FieldEntry<int> { \
public: \
FieldEntry() { \
static_assert( \
std::is_same_v<int, typename std::underlying_type_t<EnumClass>>, \
      "enum class must be backed by int");  \
is_enum_ = true; \
  }  \
using Super = FieldEntry<int>; \
void Set(void *head, const std::string &value) const override { \
Super::Set(head, value); \
  }  \
inline FieldEntry<EnumClass>& add_enum(const std::string &key, EnumClass value) { \
Super::add_enum(key, static_cast<int>(value)); \
return *this; \
  }  \
inline FieldEntry<EnumClass>& set_default(const EnumClass& default_value) { \
default_value_ = static_cast<int>(default_value); \
has_default_ = true; \
return *this; \
  }  \
inline void Init(const std::string &key, void *head, EnumClass& ref) {  \
Super::Init(key, head, *reinterpret_cast<int*>(&ref)); \
  }  \
};  \
}  \
} 
 
enum class Foo : int {
kBar = 0, kFrog = 1, kCat = 2, kDog = 3
};
 
 
struct MyParam : dmlc::Parameter<MyParam> {
Foo foo;
DMLC_DECLARE_PARAMETER(MyParam) {
DMLC_DECLARE_FIELD(foo)
.set_default(Foo::kBar)
.add_enum("bar", Foo::kBar)
.add_enum("frog", Foo::kFrog)
.add_enum("cat", Foo::kCat)
.add_enum("dog", Foo::kDog);
  }
};
 
DMLC_REGISTER_PARAMETER(MyParam);
DECLARE_FIELD_ENUM_CLASS(xgboost::DataSplitMode)