22 General utilities library [utilities]

22.8 Expected objects [expected]

22.8.3 Class template unexpected [expected.unexpected]

22.8.3.3 Observers [expected.un.obs]

constexpr const E& error() const & noexcept; constexpr E& error() & noexcept;
Returns: unex.
constexpr E&& error() && noexcept; constexpr const E&& error() const && noexcept;
Returns: std​::​move(unex).