std::is_trivial

template< class T >
struct is_trivial;

If T is a trivial type, provides the member constant value equal to true. For any other type, value is false.

The behavior is undefined if std::remove_all_extents_t<T> is an incomplete type and not (possibly cv-qualified) void.

The behavior of a program that adds specializations for is_trivial or is_trivial_v (since C++17) is undefined.

Template parameters

Helper variable template

template< class T >
inline constexpr bool is_trivial_v = is_trivial<T>::value;

Possible implementation

template<class T>
struct is_trivial : std::integral_constant< 
    bool,
    std::is_trivially_copyable<T>::value &&
    std::is_trivially_default_constructible<T>::value 
> {};

Example

#include <iostream>
#include <type_traits>
 
struct A
{
    int m;
};
 
struct B
{
    B() {}
};
 
int main() 
{
    std::cout << std::boolalpha;
    std::cout << std::is_trivial<A>::value << '\n';
    std::cout << std::is_trivial<B>::value << '\n';
}

true
false

See also