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std::derived_from

From cppreference.com
< cpp‎ | concepts
Defined in header <concepts>
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 behaviour is different to std::is_base_of when Base is a private or protected base of Derived.

[edit] Example

#include <concepts>
 
class A {};
 
class B: public A {};
 
class C: private A{};
 
int main() {
    // 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
}

[edit] See also

checks if a type is derived from the other type
(class template) [edit]
checks if a type can be converted to the other type
(class template) [edit]