#include<type_traits>

template< class T >
struct is_nothrow_copy_assignable;

std::is_nothrow_copy_assignable< datatype >::value << '\n'

// C++ program to illustrate
// std::is_nothrow_copy_assignable
#include <bits/stdc++.h>
#include <type_traits>
using namespace std;
  
// Declare structures X and Y
struct X {
};
  
struct Y {
    Y& operator=(const Y&)
    {
        return *this;
    }
};
  
// Declare classes
class A {
};
  
class B {
    B() {}
};
  
class C : B {
};
  
class D {
    virtual void fn() {}
};
  
// Driver Code
int main()
{
    cout << std::boolalpha;
  
    // Check if int is is nothrow
    // copy assignable or not
    cout << "int: "
         << is_nothrow_copy_assignable<int>::value
         << endl;
  
    // Check if struct X is nothrow
    // copy assignable or not
    cout << "struct X: "
         << is_nothrow_copy_assignable<X>::value
         << endl;
  
    // Check if struct Y is isnothrow
    // copy assignable or not
    cout << "struct Y: "
         << is_nothrow_copy_assignable<Y>::value
         << endl;
  
    // Check if int[2] is is nothrow
    // copy assignable or not
    cout << "int[2]: "
         << is_nothrow_copy_assignable<int[2]>::value
         << endl;
  
    // Check if class A is a nothrow
    // copy assignable or not
    cout << "class A: "
         << is_nothrow_copy_assignable<A>::value
         << endl;
  
    // Check if class B is a nothrow
    // copy assignable or not
    cout << "class B: "
         << is_nothrow_copy_assignable<B>::value
         << endl;
  
    // Check if class C is a nothrow
    // copy assignable or not
    cout << "class C: "
         << is_nothrow_copy_assignable<C>::value
         << endl;
  
    // Check if class D is a nothrow
    // copy assignable or not
    cout << "class D: "
         << is_nothrow_copy_assignable<D>::value
         << endl;
    return 0;
}

int: true
struct X: true
struct Y: false
int[2]: false
class A: true
class B: true
class C: true
class D: true