std::is_destructible,std::is_trivially_destructible,std::is_nothrow_destructible(3)

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

Synopsis
   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 T is a reference type, provides the member constant value equal to true.
   If T is (possibly cv-qualified) void, a function type, or an array of unknown bound,
   value equals false.
   If T is an object type, then, for the type U equal to
   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.
   The behavior of a program that adds specializations for any of the templates
   described on this page is undefined.
  Helper variable templates
   template< class T > (since C++17)
   inline constexpr bool is_destructible_v = is_destructible<T>::value;
   template< class T >
   inline constexpr bool is_trivially_destructible_v = (since C++17)
   is_trivially_destructible<T>::value;
   template< class T >
   inline constexpr bool is_nothrow_destructible_v = (since C++17)
   is_nothrow_destructible<T>::value; Inherited from std::integral_constant

Member constants
   value true if T is destructible, 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
   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.

Example
// 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 trivially destructible? "
               << std::is_trivially_destructible_v<Foo> << '\n'
               << "Foo is nothrow destructible? "
               << std::is_nothrow_destructible<Foo>() << '\n'
               << "Bar is trivially destructible? "
               << std::is_trivially_destructible<Bar>{} << '\n';
 }

Output:
 std::string is destructible? true
 Foo is trivially destructible? false
 Foo is nothrow destructible? true
 Bar is trivially destructible? true
  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 2049 C++11 the specification was incompletable because of made complete
                       the imaginary wrapping struct

See also
   is_constructible
   is_trivially_constructible
   is_nothrow_constructible checks if a type has a constructor for specific arguments
   (C++11) (class template)
   (C++11)
   (C++11)
   has_virtual_destructor checks if a type has a virtual destructor
   (C++11) (class template)
   destructible specifies that an object of the type can be destroyed
   (C++20) (concept)
   destructor releases claimed resources