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std::derived_from - cppreference.com

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template< class Derived, class Base > concept derived_from = std::is_base_of_v<Base, Derived> && std::is_convertible_v<const volatile Derived*, const volatile Base*>;

 (since C++20)

The concept derived_from<Derived, Base> is satisfied if and only if Base is a class type that is either Derived or a public and unambiguous base of Derived, ignoring cv-qualifiers.

Note that this behavior is different to std::is_base_of when Base is a private or protected base of Derived.

Example

#include <concepts>

class A {};

class B : public A {};

class C : private A {};

// std::derived_from == true only for public inheritance or exact same class
static_assert(std::derived_from<B, B> == true);      // same class: true
static_assert(std::derived_from<int, int> == false); // same primitive type: false
static_assert(std::derived_from<B, A> == true);      // public inheritance: true
static_assert(std::derived_from<C, A> == false);     // private inheritance: false

// std::is_base_of == true also for private inheritance
static_assert(std::is_base_of_v<B, B> == true);      // same class: true
static_assert(std::is_base_of_v<int, int> == false); // same primitive type: false
static_assert(std::is_base_of_v<A, B> == true);      // public inheritance: true
static_assert(std::is_base_of_v<A, C> == true);      // private inheritance: true

int main() {}

References

  • C++23 standard (ISO/IEC 14882:2024):
  • 18.4.3 Concept derived_from [concept.derived]
  • C++20 standard (ISO/IEC 14882:2020):
  • 18.4.3 Concept derived_from [concept.derived]

See also