std::derived_from

Since C++20

Header: <concepts>

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.

# Declarations

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)

# 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() {}

# See also