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

template< class T >
struct is_destructible;

template< class T >
struct is_trivially_destructible;

template< class T >
struct is_nothrow_destructible;

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 >
inline constexpr bool is_destructible_v = is_destructible<T>::value;

template< class T >
inline constexpr bool is_trivially_destructible_v = is_trivially_destructible<T>::value;

template< class T >
inline constexpr bool is_nothrow_destructible_v = is_nothrow_destructible<T>::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

#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