22 General utilities library [utilities]

22.8 Expected objects [expected]

22.8.7 Partial specialization of expected for void types [expected.void] Swap [expected.void.swap]

constexpr void swap(expected& rhs) noexcept(see below);
Constraints: is_swappable_v<E> is true and is_move_constructible_v<E> is true.
Effects: See Table 68.
Table 68: swap(expected&) effects [tab:expected.void.swap]
no effects
calls rhs.swap(*this)
see below
equivalent to: using std​::​swap; swap(unex, rhs.unex);
For the case where rhs.has_value() is false and this->has_value() is true, equivalent to: construct_at(addressof(unex), std::move(rhs.unex)); destroy_at(addressof(rhs.unex)); has_val = false; rhs.has_val = true;
Throws: Any exception thrown by the expressions in the Effects.
Remarks: The exception specification is equivalent to is_nothrow_move_constructible_v<E> && is_nothrow_swappable_v<E>.
friend constexpr void swap(expected& x, expected& y) noexcept(noexcept(x.swap(y)));
Effects: Equivalent to x.swap(y).