std::copy_constructible

 

C++

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Named requirements

Feature test macros (C++20)

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Concepts library (C++20)

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Technical specifications

Symbols index

External libraries

 

Concepts library

Core language concepts same_as derived_from convertible_to common_reference_with      common_with integral signed_integral unsigned_integral floating_point swappableswappable_with destructible constructible_from default_initializable move_constructible copy_constructible assignable_from

Comparison concepts equality_comparableequality_comparable_with totally_orderedtotally_ordered_with Object concepts movable copyable semiregular regular Callable concepts invocableregular_invocable predicate relation equivalence_relation strict_weak_order

Exposition-only concepts boolean-testable

 

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.

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)