20 Memory management library [mem]

20.3 Smart pointers [smartptr]

20.3.1 Unique-ownership pointers [unique.ptr]

20.3.1.3 unique_ptr for single objects [unique.ptr.single]

20.3.1.3.4 Assignment [unique.ptr.single.asgn]

constexpr unique_ptr& operator=(unique_ptr&& u) noexcept;

Constraints: is_move_assignable_v<D> is true.

Preconditions: If D is not a reference type, D meets the Cpp17MoveAssignable requirements (Table 33) and assignment of the deleter from an rvalue of type D does not throw an exception.

Otherwise, D is a reference type; remove_reference_t<D> meets the Cpp17CopyAssignable requirements and assignment of the deleter from an lvalue of type D does not throw an exception.

Effects: Calls reset(u.release()) followed by get_deleter() = std::forward<D>(u.get_deleter()).

Postconditions: If this != addressof(u), u.get() == nullptr, otherwise u.get() is unchanged.

Returns: *this.

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template<class U, class E> constexpr unique_ptr& operator=(unique_ptr<U, E>&& u) noexcept;

Constraints:

(6.1)
unique_ptr<U, E>::pointer is implicitly convertible to pointer, and
(6.2)
U is not an array type, and
(6.3)
is_assignable_v<D&, E&&> is true.

Preconditions: If E is not a reference type, assignment of the deleter from an rvalue of type E is well-formed and does not throw an exception.

Otherwise, E is a reference type and assignment of the deleter from an lvalue of type E is well-formed and does not throw an exception.

Effects: Calls reset(u.release()) followed by get_deleter() = std::forward<E>(u.get_deleter()).

Postconditions: u.get() == nullptr.

Returns: *this.

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constexpr unique_ptr& operator=(nullptr_t) noexcept;

Effects: As if by reset().

Postconditions: get() == nullptr.

Returns: *this.