std::experimental::propagate_const<T>::operator=

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constexpr propagate_const& operator= ( propagate_const&& p ) = default ;
(1) (library fundamentals TS v2)
template < class U >
constexpr propagate_const& operator= ( propagate_const<U> && pu ) ;
(2) (library fundamentals TS v2)
template < class U >
constexpr propagate_const& operator= ( U&& u ) ;
(3) (library fundamentals TS v2)
propagate_const& operator= ( const propagate_const& ) = delete;
(4) (library fundamentals TS v2)

Let t_ designate the private data member that is the wrapped pointer-like object.

1) Explicitly defaulted move assignment operator that move assigns this->t_ from p.t_
2) Assigns std::move(pu.t_) to this->t_.
This overload participates in overload resolution only if U is implicitly convertible to T
3) Assigns std::forward <U> (u) to this->t_.
This overload participates in overload resolution only if U is implicitly convertible to T and std::decay_t<U> is not a specialization of propagate_const
4) Copy assignment operator is explicitly deleted. propagate_const is non-copyable.

Parameters

p - another propagate_const object to move from
pu - another propagate_const object of a different specialization to move from
u - another object to assign to the contained pointer

Return value

*this.