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Showing content from https://cplusplus.com/reference/type_traits/is_trivial/ below:

class template

<type_traits>

std::is_trivial

template <class T> struct is_trivial;

Is trivial type

Trait class that identifies whether T is a trivial type.

A trivial type is a type whose storage is contiguous (trivially copyable) and which only supports static default initialization (trivially default constructible), either cv-qualified or not. It includes scalar types, trivial classes and arrays of any such types.

A trivial class is a class (defined with class, struct or union) that is both trivially default constructible and trivially copyable, which implies that:

uses the implicitly defined default, copy and move constructors, copy and move assignments, and destructor.
has no virtual members.
has no non-static data members with brace- or equal- initializers.
its base class and non-static data members (if any) are themselves also trivial types.

is_trivial inherits from integral_constant as being either true_type or false_type, depending on whether T is a trivial type.

Template parameters

T: A complete type, or void (possible cv-qualified), or an array of unknown bound of a complete element type.

Member types Inherited from integral_constant:

Member constants Inherited from integral_constant:
member constant definition value either true or false
Member functions Inherited from integral_constant:

operator bool: Returns value (public member function)

Example

// is_trivial example
#include <iostream>
#include <type_traits>

class A {};
class B { B() {} };
class C : B {};
class D { virtual void fn() {} };

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_trivial:" << std::endl;
  std::cout << "int: " << std::is_trivial<int>::value << std::endl;
  std::cout << "A: " << std::is_trivial<A>::value << std::endl;
  std::cout << "B: " << std::is_trivial<B>::value << std::endl;
  std::cout << "C: " << std::is_trivial<C>::value << std::endl;
  std::cout << "D: " << std::is_trivial<D>::value << std::endl;
  return 0;
}

Output:

is_trivial:
int: true
A: true
B: false
C: false
D: false