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std::copy_constructible

From cppreference.com
< cpp‎ | concepts
 
C++
 
Concepts library
Exposition-only concepts
 (C++20)
 
Defined in header <concepts>
template< class T >

concept copy_constructible =
    std::move_constructible<T> &&
    std::constructible_from<T, T&> && std::convertible_to<T&, T> &&
    std::constructible_from<T, const T&> && std::convertible_to<const T&, T> &&

    std::constructible_from<T, const T> && std::convertible_to<const T, T>;
 (since C++20)

The concept copy_constructible is satisfied if T is an lvalue reference type, or if it is a move_constructible object type where an object of that type can constructed from a (possibly const) lvalue or const rvalue of that type in both direct- and copy-initialization contexts with the usual semantics (a copy is constructed with the source unchanged).

[edit] Semantic requirements

If T is an object type, then copy_constructible<T> is modeled only if given

  • v, an lvalue of type (possibly const) T or an rvalue of type const T,

the following are true:

  • After the definition T u = v;, u is equal to v and v is not modified;
  • T(v) is equal to v and does not modify v.

[edit] References

  • C++23 standard (ISO/IEC 14882:2024):
  • 18.4.14 Concept copy_constructible [concept.copyconstructible]
  • C++20 standard (ISO/IEC 14882:2020):
  • 18.4.14 Concept copy_constructible [concept.copyconstructible]

[edit] See also

(C++11)(C++11)(C++11)
 checks if a type has a copy constructor
(class template) [edit]
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