cppdraft_translate/cppdraft/expected/void/cons.md

[expected.void.cons]

22 General utilities library [utilities]

22.8 Expected objects [expected]

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

22.8.7.2 Constructors [expected.void.cons]

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constexpr expected() noexcept;

1

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Postconditions: has_value() is true.

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constexpr expected(const expected& rhs);

2

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Effects: If rhs.has_value() is false, direct-non-list-initializes unex with rhs.error().

3

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Postconditions: rhs.has_value() == this->has_value().

4

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Throws: Any exception thrown by the initialization of unex.

5

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Remarks: This constructor is defined as deleted unless is_copy_constructible_v is true.

6

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This constructor is trivial if is_trivially_copy_constructible_v is true.

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constexpr expected(expected&& rhs) noexcept(is_nothrow_move_constructible_v<E>);

7

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Constraints: is_move_constructible_v is true.

8

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Effects: If rhs.has_value() is false, direct-non-list-initializes unex with std​::​move(rhs.error()).

9

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Postconditions: rhs.has_value() is unchanged;rhs.has_value() == this->has_value() is true.

10

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Throws: Any exception thrown by the initialization of unex.

11

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Remarks: This constructor is trivial if is_trivially_move_constructible_v is true.

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template<class U, class G> constexpr explicit(!is_convertible_v<const G&, E>) expected(const expected<U, G>& rhs); template<class U, class G> constexpr explicit(!is_convertible_v<G, E>) expected(expected<U, G>&& rhs);

12

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Let GF be const G& for the first overload andG for the second overload.

13

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Constraints:

• (13.1)

is_void_v is true; and

• (13.2)

is_constructible_v<E, GF> is true; and

• (13.3)

is_constructible_v<unexpected, expected<U, G>&> is false; and

• (13.4)

is_constructible_v<unexpected, expected<U, G>> is false; and

• (13.5)

is_constructible_v<unexpected, const expected<U, G>&> is false; and

• (13.6)

is_constructible_v<unexpected, const expected<U, G>> is false.

14

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Effects: If rhs.has_value() is false, direct-non-list-initializes unex with std​::​forward(rhs.error()).

15

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Postconditions: rhs.has_value() is unchanged;rhs.has_value() == this->has_value() is true.

16

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Throws: Any exception thrown by the initialization of unex.

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template<class G> constexpr explicit(!is_convertible_v<const G&, E>) expected(const unexpected<G>& e); template<class G> constexpr explicit(!is_convertible_v<G, E>) expected(unexpected<G>&& e);

17

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Let GF be const G& for the first overload andG for the second overload.

18

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Constraints: is_constructible_v<E, GF> is true.

19

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Effects: Direct-non-list-initializes unex with std​::​forward(e.error()).

20

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Postconditions: has_value() is false.

21

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Throws: Any exception thrown by the initialization of unex.

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constexpr explicit expected(in_place_t) noexcept;

22

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Postconditions: has_value() is true.

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template<class... Args> constexpr explicit expected(unexpect_t, Args&&... args);

23

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Constraints: is_constructible_v<E, Args...> is true.

24

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Effects: Direct-non-list-initializes unex with std​::​forward(args)....

25

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Postconditions: has_value() is false.

26

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Throws: Any exception thrown by the initialization of unex.

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template<class U, class... Args> constexpr explicit expected(unexpect_t, initializer_list<U> il, Args&&... args);

27

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Constraints: is_constructible_v<E, initializer_list&, Args...> is true.

28

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Effects: Direct-non-list-initializes unex with il, std​::​forward(args)....

29

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Postconditions: has_value() is false.

30

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Throws: Any exception thrown by the initialization of unex.