std::is_destructible,std::is_trivially_destructible,std::is_nothrow_destructible (3) - Linux Man Pages

std::is_destructible,std::is_trivially_destructible,std::is_nothrow_destructible: std::is_destructible,std::is_trivially_destructible,std::is_nothrow_destructible


std::is_destructible,std::is_trivially_destructible,std::is_nothrow_destructible - std::is_destructible,std::is_trivially_destructible,std::is_nothrow_destructible


Defined in header <type_traits>
template< class T > (1) (since C++11)
struct is_destructible;
template< class T > (2) (since C++11)
struct is_trivially_destructible;
template< class T > (3) (since C++11)
struct is_nothrow_destructible;

1) If an imaginary struct containing a member object of type T has a non-deleted destructor, provides the member constant value equal true. For any other type, value is false. (until C++14)
1) If T is a reference type, provides the member constant value equal true
If T is (possibly cv-qualified) void, a function type, or an array of unknown bound, value equals false. (since C++14)
If T is an object type, then, for the type U equal std::remove_all_extents<T>::type, if the expression std::declval<U&>().~U() is well-formed in unevaluated context, value equals true. Otherwise, value equals false.

2) same as 1), and additionally std::remove_all_extents<T>::type is either a non-class type or a class type with a trivial destructor.
3) same as 1), but the destructor is noexcept.
T shall be a complete type, (possibly cv-qualified) void, or an array of unknown bound. Otherwise, the behavior is undefined.
If an instantiation of a template above depends, directly or indirectly, on an incomplete type, and that instantiation could yield a different result if that type were hypothetically completed, the behavior is undefined.

Helper variable templates

template< class T > (since C++17)
inline constexpr bool is_destructible_v = is_destructible<T>::value;
template< class T > (since C++17)
inline constexpr bool is_trivially_destructible_v = is_trivially_destructible<T>::value;
template< class T > (since C++17)
inline constexpr bool is_nothrow_destructible_v = is_nothrow_destructible<T>::value;

Inherited from std::integral_constant

Member constants

value true if T is destructible, false otherwise
         (public static member constant)

Member functions

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

operator() returns value
              (public member function)

Member types

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


Because the C++ program terminates if a destructor throws an exception during stack unwinding (which usually cannot be predicted), all practical destructors are non-throwing even if they are not declared noexcept. All destructors found in the C++ standard library are non-throwing.
Storage occupied by trivially destructible objects may_be_reused without calling the destructor.


// Run this code

  #include <iostream>
  #include <string>
  #include <type_traits>
  struct Foo {
     std::string str;
     ~Foo() noexcept {};
  struct Bar {
      ~Bar() = default;
  int main() {
      std::cout << std::boolalpha
                << "std::string is destructible? "
                << std::is_destructible<std::string>::value << '\n'
                << "Foo is nothrow destructible? "
                << std::is_nothrow_destructible<Foo>::value << '\n'
                << "Bar is trivally destructible? "
                << std::is_trivially_destructible<Bar>::value << '\n';


  std::string is destructible? true
  Foo is nothrow destructible? true
  Bar is trivally destructible? true

See also

is_nothrow_constructible checks if a type has a constructor for specific arguments
                           (class template)

has_virtual_destructor checks if a type has a virtual destructor
                           (class template)