std::is_implicit_lifetime

Since C++23

Header: <type_traits>

std::is_implicit_lifetime is a UnaryTypeTrait.

# Declarations

template< class T >
struct is_implicit_lifetime;

(since C++23)

# Notes

Feature-test macro Value Std Feature __cpp_lib_is_implicit_lifetime 202302L (C++23) std::is_implicit_lifetime

# Example

// The following types are collectively called implicit-lifetime types:
// * scalar types:
//     * arithmetic types
//     * enumeration types
//     * pointer types
//     * pointer-to-member types
//     * std::nullptr_t
// * implicit-lifetime class types
//     * is an aggregate whose destructor is not user-provided
//     * has at least one trivial eligible constructor and a trivial,
//       non-deleted destructor
// * array types
// * cv-qualified versions of these types.
#include <type_traits>
 
static_assert(std::is_implicit_lifetime_v<int>); // arithmetic type is a scalar type
static_assert(std::is_implicit_lifetime_v<const int>); // cv-qualified a scalar type
 
enum E { e };
static_assert(std::is_implicit_lifetime_v<E>); // enumeration type is a scalar type
static_assert(std::is_implicit_lifetime_v<int*>); // pointer type is a scalar type
static_assert(std::is_implicit_lifetime_v<std::nullptr_t>); // scalar type
 
struct S { int x, y; };
// S is an implicit-lifetime class: an aggregate without user-provided destructor
static_assert(std::is_implicit_lifetime_v<S>);
 
static_assert(std::is_implicit_lifetime_v<int S::*>); // pointer-to-member
 
struct X { ~X() = delete; };
// X is not implicit-lifetime class due to deleted destructor
static_assert(!std::is_implicit_lifetime_v<X>);
 
static_assert(std::is_implicit_lifetime_v<int[8]>); // array type
static_assert(std::is_implicit_lifetime_v<volatile int[8]>); // cv-qualified array type
 
int main() {}

# See also