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std::has_vi...l_destructor(3) C++ Standard Libarystd::has_vi...l_destructor(3) NAME std::has_virtual_destructor - std::has_virtual_destructor Synopsis Defined in header <type_traits> template< class T > (since C++11) struct has_virtual_destructor; 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 unde- fined. If the program adds specializations for std::has_virtual_destructor or std::has_virtual_destructor_v, the behavior is undefined. Template parameters T - a type to check Helper variable template template< class T > inline constexpr bool has_virtual_destructor_v = (since C++17) has_virtual_destructor<T>::value; Inherited from std::integral_constant Member constants value true if T has a virtual destructor, false otherwise [static] (public static member constant) Member functions operator bool converts the object to bool, returns value (public member function) operator() returns value (C++14) (public member function) Member types Type Definition value_type bool type std::integral_constant<bool, 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). In this case, std::is_polymorphic<C>::value is true. Example // Run this code #include <type_traits> struct S {}; static_assert(!std::has_virtual_destructor_v<S>); struct B { virtual ~B() {} }; static_assert(std::has_virtual_destructor_v<B>); struct D : B { ~D() {} }; static_assert(std::has_virtual_destructor_v<D>); int main() { B* pd = new D; delete pd; } Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct be- havior LWG 2015 C++11 the behavior was undefined if the base charac- teristic is T is an incomplete union type std::false_type in this case See also is_destructible is_trivially_destructible is_nothrow_destructible checks if a type has a non-deleted de- structor (C++11) (class template) (C++11) (C++11) is_polymorphic checks if a type is a polymorphic class type (C++11) (class template) http://cppreference.com 2024.06.10 std::has_vi...l_destructor(3)
NAME | Synopsis | Template parameters | Member constants | Member functions | Member types | Notes | Example | See also
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