gcc_bug.h

namespace type_traits_internal {
// is_trivially_copyable()
//
// Determines whether the passed type `T` is trivially copyable.
//
// This metafunction is designed to be a drop-in replacement for the C++11
// `std::is_trivially_copyable()` metafunction for platforms that have
// incomplete C++11 support (such as libstdc++ 4.x). We use the C++17 definition
// of TriviallyCopyable.
//
// NOTE: `is_trivially_copyable<T>::value` is `true` if all of T's copy/move
// constructors/assignment operators are trivial or deleted, T has at least
// one non-deleted copy/move constructor/assignment operator, and T is trivially
// destructible. Arrays of trivially copyable types are trivially copyable.
//
// We expose this metafunction only for internal use within absl.
template <typename T>
class is_trivially_copyable_impl {
  using ExtentsRemoved = typename std::remove_all_extents<T>::type;
  static constexpr bool kIsCopyOrMoveConstructible =
      std::is_copy_constructible<ExtentsRemoved>::value ||
      std::is_move_constructible<ExtentsRemoved>::value;
  static constexpr bool kIsCopyOrMoveAssignable =
      absl::is_copy_assignable<ExtentsRemoved>::value ||
      absl::is_move_assignable<ExtentsRemoved>::value;

 public:
  static constexpr bool kValue =
      (__has_trivial_copy(ExtentsRemoved) || !kIsCopyOrMoveConstructible) &&
      (__has_trivial_assign(ExtentsRemoved) || !kIsCopyOrMoveAssignable) &&
      (kIsCopyOrMoveConstructible || kIsCopyOrMoveAssignable) &&
      is_trivially_destructible<ExtentsRemoved>::value &&
      // We need to check for this explicitly because otherwise we'll say
      // references are trivial copyable when compiled by MSVC.
      !std::is_reference<ExtentsRemoved>::value;
};

template <typename T>
struct is_trivially_copyable
    : std::integral_constant<
          bool, type_traits_internal::is_trivially_copyable_impl<T>::kValue> {};
}  // namespace type_traits_internal