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std::unwrap_reference, std::unwrap_ref_decay

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Defined in header <type_traits>
Defined in header <functional>
template< class T >
struct unwrap_reference;
 (1) (since C++20)
template< class T >
struct unwrap_ref_decay;
 (2) (since C++20)

Unwraps any std::reference_wrapper: changing std::reference_wrapper<U> to U&.

1) If T is a specialization of std::reference_wrapper, unwraps it; otherwise, T remains the same.
2) If the decayed T is a specialization of std::reference_wrapper, unwraps it; otherwise, T is decayed.

If the program adds specializations for any of the templates described on this page, the behavior is undefined.

Contents

[edit] Nested types

Type Definition
type

(1) U& if T is std::reference_wrapper<U>; T otherwise
(2) U& if std::decay_t<T> is std::reference_wrapper<U>; std::decay_t<T> otherwise

[edit] Helper types

template<class T>
using unwrap_reference_t = unwrap_reference<T>::type;
 (1) (since C++20)
template<class T>
using unwrap_ref_decay_t = unwrap_ref_decay<T>::type;
 (2) (since C++20)

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