< cpp‎ | types
Metaprogramming library
Type traits
Type categories
Type properties
(C++11)(until C++20*)
(C++11)(deprecated in C++20)
Type trait constants
Supported operations
Relationships and property queries
Type modifications
Type transformations
(C++11)(deprecated in C++23)
(C++11)(deprecated in C++23)

(C++11)(until C++20*)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
Defined in header <type_traits>
template< class T >
struct has_virtual_destructor;
(since C++11)

std::has_virtual_destructor is a UnaryTypeTrait.

If T is a type with a virtual destructor, the base characteristic is std::true_type. For any other type, the base characteristic is std::false_type.

If T is an incomplete non-union class type, the behavior is undefined.

If the program adds specializations for std::has_virtual_destructor or std::has_virtual_destructor_v, the behavior is undefined.


[edit] Template parameters

T - a type to check

[edit] Helper variable template

template< class T >
inline constexpr bool has_virtual_destructor_v = has_virtual_destructor<T>::value;
(since C++17)

Inherited from std::integral_constant

Member constants

true if T has a virtual destructor, false otherwise
(public static member constant)

Member functions

operator bool
converts the object to bool, returns value
(public member function)
returns value
(public member function)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

[edit] 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). In this case, std::is_polymorphic<C>::value is true.

[edit] Example

#include <type_traits>
struct S {};
struct B { virtual ~B() {} };
struct D : B { ~D() {} };
int main()
    B* pd = new D;
    delete pd;

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 2015 C++11 the behavior was undefined if
T is an incomplete union type
the base characteristic is
std::false_type in this case

[edit] See also

checks if a type has a non-deleted destructor
(class template) [edit]
checks if a type is a polymorphic class type
(class template) [edit]