//   total number of types, hence typeList is pre-allocated.
	if len(p.typeData) == 0 {
		if n != len(p.typeList) {
			p.errorf("invalid type number %d (out of sync)", n)
		}
		p.typeList = append(p.typeList, reserved)
	} else {
		if p.typeList[n] != nil {
			p.errorf("previously visited type number %d", n)
		}
		p.typeList[n] = reserved
	}
}

class TFTensorType
    : public mlir::Type::TypeBase<TFTensorType, mlir::Type, mlir::TypeStorage> {
 public:
  using Base::Base;
  static constexpr mlir::StringLiteral name = "tensorflow.tf_mlrt.tf_tensor";
};

// The MLIR type represents a tensorflow::Device*
class TFDeviceType
    : public mlir::Type::TypeBase<TFDeviceType, mlir::Type, mlir::TypeStorage> {
 public:
  using Base::Base;

    return {getTrailingObjects<StringAttr>(), num_attrs};
  }

  unsigned num_attrs;
};

template <typename Derived>
class TFRTypeImpl : public Type::TypeBase<Derived, TFRType, TFRTypeStorage> {
 public:
  using Base = Type::TypeBase<Derived, TFRType, TFRTypeStorage>;
  using TFRBase = TFRTypeImpl<Derived>;
  using Base::Base;

  static Derived get(ArrayRef<StringAttr> attrs, MLIRContext* context) {

};

// The MLIR type represents a tensorflow::Tensor.
class TFTensorType : public Type::TypeBase<TFTensorType, Type, TypeStorage> {
 public:
  using Base::Base;
  static constexpr StringLiteral name = "tfrt.tf_tensor";
};

// The MLIR type represents a tensorflow::Allocator.
class TFAllocatorType
    : public Type::TypeBase<TFAllocatorType, Type, TypeStorage> {
 public:
  using Base::Base;

			} else {
				t = prev.typemap[typeOff(tl)]
			}
			// Add to typehash if not seen before.
			tlist := typehash[t.Hash]
			for _, tcur := range tlist {
				if tcur == t {
					continue collect
				}
			}
			typehash[t.Hash] = append(tlist, t)
		}

		if md.typemap == nil {
			// If any of this module's typelinks match a type from a

// The Control type is a token-like value that models control dependencies from
// TensorFlow graphs.
class ControlType : public Type::TypeBase<ControlType, Type, TypeStorage> {
 public:
  using Base::Base;
  static constexpr ::mlir::StringLiteral name = "tf_executor.control";
};

class TokenType : public Type::TypeBase<TokenType, Type, TypeStorage> {
 public:
  using Base::Base;
  static constexpr ::mlir::StringLiteral name = "tf_executor.token";

		// already instantiated
		// For each (existing) type argument determine if it needs
		// to be substituted; i.e., if it is or contains a type parameter
		// that has a type argument for it.
		targs, updated := subst.typeList(t.TypeArgs().list())
		if updated {
			return subst.check.newAliasInstance(subst.pos, t.orig, targs, subst.ctxt)
		}

	case *Array:
		elem := subst.typOrNil(t.elem)
		if elem != t.elem {

		// already instantiated
		// For each (existing) type argument determine if it needs
		// to be substituted; i.e., if it is or contains a type parameter
		// that has a type argument for it.
		targs, updated := subst.typeList(t.TypeArgs().list())
		if updated {
			return subst.check.newAliasInstance(subst.pos, t.orig, targs, subst.ctxt)
		}

	case *Array:
		elem := subst.typOrNil(t.elem)
		if elem != t.elem {

};

]]

// The TypeList template makes it possible to use either a single type
// or a Types<...> list in TYPED_TEST_CASE() and
// INSTANTIATE_TYPED_TEST_CASE_P().

template <typename T>
struct TypeList {
  typedef Types1<T> type;
};


$range i 1..n
template <$for i, [[typename T$i]]>
struct TypeList<Types<$for i, [[T$i]]> > {

type Alias struct {
	obj     *TypeName      // corresponding declared alias object
	orig    *Alias         // original, uninstantiated alias
	tparams *TypeParamList // type parameters, or nil
	targs   *TypeList      // type arguments, or nil
	fromRHS Type           // RHS of type alias declaration; may be an alias
	actual  Type           // actual (aliased) type; never an alias
}