std::copy_constructible (since C++20)

 

C++

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Feature test macros (C++20)

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External libraries

 

Concepts library

Core language concepts same_as (C++20) derived_from (C++20) convertible_to (C++20) common_reference_with (C++20) common_with (C++20) integral (C++20) signed_integral (C++20) unsigned_integral (C++20) floating_point (C++20) swappableswappable_with (C++20)(C++20) destructible (C++20) constructible_from (C++20) default_initializable (C++20)   move_constructible (C++20) copy_constructible (C++20) assignable_from (C++20)

Comparison concepts equality_comparableequality_comparable_with (C++20)(C++20) totally_orderedtotally_ordered_with (C++20)(C++20) Object concepts movable (C++20) copyable (C++20) semiregular (C++20) regular (C++20) Callable concepts invocableregular_invocable (C++20)(C++20) predicate (C++20) relation (C++20) equivalence_relation (C++20) strict_weak_order (C++20)

Exposition-only concepts boolean-testable  (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).

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.

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]

See also

is_copy_constructibleis_trivially_copy_constructibleis_nothrow_copy_constructible (C++11)(C++11)(C++11)

checks if a type has a copy constructor (class template)