// *containing* linked_ptr<> must have a constructor and destructor (even
// if they do nothing!).
//
// Bill Gibbons suggested we use something like this.
//
// Thread Safety:
//   Unlike other linked_ptr implementations, in this implementation
//   a linked_ptr object is thread-safe in the sense that:
//     - it's safe to copy linked_ptr objects concurrently,
//     - it's safe to copy *from* a linked_ptr and read its underlying

  /// co-located on the device where op is placed.
  /// NOTE: This function is intended to be use internal libraries only for
  /// controlling placement of ops on to devices. Public use is not encouraged
  /// because the implementation of device placement is subject to change.
  Scope ColocateWith(const Operation& op) const;
  /// Convenience function for above.
  Scope ColocateWith(const Output& out) const { return ColocateWith(out.op()); }

    // their declared shapes for computations. Must be non-empty.
    std::vector<XlaShapeLayoutHelpers::ShapeDeterminationFns>
        shape_determination_fns;

    // If padded_shape_fn is empty, a default implementation that returns
    // the logical on-device shape without padding is used.
    PaddedShapeFn padded_shape_fn;

    // Set of devices to use. This controls which of the devices on the given

///
/// Hashable TaggedValues overload `AbslHashValue`. Non-hashable structures
/// return 0.
template <>
struct TaggedValueHash<TaggedValue> {
  size_t operator()(const TaggedValue& v) const;
};

/// @brief Hash implementation for TaggedValue Tuples.
template <>
struct TaggedValueHash<Tuple> {
  size_t operator()(const Tuple& t) const;
};

/// @brief The basic `TaggedValue` tagged union type.
///

// for more examples.
//
// In the future, we plan to publish the API for defining new parameter
// generators. But for now this interface remains part of the internal
// implementation and is subject to change.
//
//
// A parameterized test fixture must be derived from testing::Test and from
// testing::WithParamInterface<T>, where T is the type of the parameter

template <typename T>
std::string GetTypeName() {
# if GTEST_HAS_RTTI

  const char* const name = typeid(T).name();
#  if GTEST_HAS_CXXABI_H_ || defined(__HP_aCC)
  int status = 0;
  // gcc's implementation of typeid(T).name() mangles the type name,
  // so we have to demangle it.
#   if GTEST_HAS_CXXABI_H_
  using abi::__cxa_demangle;
#   endif  // GTEST_HAS_CXXABI_H_

TF_CAPI_EXPORT extern void TFE_HostAddressSpace(TFE_Context* ctx,
                                                TF_Buffer* buf);

// APIs for generically dealing with op attributes (e.g. when forwarding them
// through custom device implementations).
//
// TODO(allenl): Currently these are black boxes, but we should have some way to
// inspect values. This would let people e.g. copy over most attributes and then
// modify some based on their values.