# std::experimental::propagate_const<T>::propagate_const

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< cpp‎ | experimental‎ | propagate const

constexpr propagate_const() = default; | (1) | (library fundamentals TS v2)
constexpr propagate_const( propagate_const&& p ) = default; | (2) | (library fundamentals TS v2)
template< class U > /* see below */ constexpr propagate_const( propagate_const<U>&& pu ); | (3) | (library fundamentals TS v2)
template< class U > /* see below */ constexpr propagate_const( U&& u ); | (4) | (library fundamentals TS v2)
propagate_const( const propagate_const& ) = delete; | (5) | (library fundamentals TS v2)

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

1) Constructs a `propagate_const`, default-initializing this->t_.
2) Explicitly defaulted move constructor that move constructs this->t_ from p.t_.
3) Initializes this->t_ as if by direct-non-list-initialization from the expression std::move(pu.t_).
This constructor does not participate in overload resolution unless std::is_constructible<T, U>::value is true, and is `explicit` if and only if std::is_convertible<U, T>::value is false.
4) Initializes this->t_ as if by direct-non-list-initialization with the expression std::forward<U>(u).
This constructor does not participate in overload resolution unless std::is_constructible<T, U>::value is true and std::decay_t<U> is not a specialization of `propagate_const`. This constructor is `explicit` if and only if std::is_convertible<U, T>::value is false.
5) Copy constructor 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 initialize the contained pointer with

### Notes

In Library Fundamental TS v2 (based on C++14), (4) and (5) are typically implemented in `explicit`/non-`explicit` overload pairs. Since Library Fundamental TS v3 (based on C++20), they can be implemented in conditional `explicit` specifiers.

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