22 General utilities library [utilities]

22.8 Expected objects [expected]

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

22.8.7.5 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 64 .

Table 64: swap(expected&) effects [tab:expected.void.swap]

🔗		this->has_value()	!this->has_value()
🔗	rhs.has_value()	no effects	calls rhs.swap(*this)
🔗	!rhs.has_value()	see below	equivalent to: using std::swap; swap(unex, rhs.unex);

For the case where rhs.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).