std::has_virtual_destructor

template< class T >
struct has_virtual_destructor;

If T is a type with a virtual destructor, provides the member constant value equal to true. For any other type, value is false.

If T is a non-union class type, T shall be a complete type; otherwise, the behavior is undefined.

The behavior of a program that adds specializations for has_virtual_destructor or has_virtual_destructor_v (since C++17) is undefined.

Template parameters

Helper variable template

template< class T >
inline constexpr bool has_virtual_destructor_v = has_virtual_destructor<T>::value;

Notes

If a class C has a public virtual destructor, it can be derived from, and the derived object can be safely deleted through a pointer to the base object (GotW #18). When true, std::is_polymorphic<C>::value is true.

Example

#include <cstdio>
#include <type_traits>
 
struct S {};
static_assert(!std::has_virtual_destructor_v<S>);
 
struct B
{
    virtual ~B() { std::puts("B::~B"); }
};
static_assert(std::has_virtual_destructor_v<B>);
 
struct D : B
{
    ~D() { std::puts("D::~D"); }
};
static_assert(std::has_virtual_destructor_v<D>);
 
int main()
{
    B* pd = new D;
    delete pd;
}

D::~D
B::~B

See also