NAME¶

std::derived_from - std::derived_from

Synopsis¶

Defined in header <concepts>
template< class Derived, class Base >

concept derived_from = (since C++20)
std::is_base_of_v<Base, Derived> &&

std::is_convertible_v<const volatile Derived*, const volatile Base*>;

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.

Example¶

// Run this code

#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
}

See also¶

is_base_of checks if a type is derived from the other type
(C++11) (class template)
is_convertible
is_nothrow_convertible checks if a type can be converted to the other type
(C++11) (class template)
(C++20)