I am expecting error that no default constructor as it is deprecated but i am not getting any error?could anyone tell?

As per cppreference doc:

The generation of the implicitly-defined copy constructor is deprecated if T has a user-defined destructor or user-defined copy assignment operator.

But i am not getting any error like default constructor not present.Please correct me if i am wrong.

#include <iostream>

class Demo
{
    int val = 100;
public:
  ~Demo()
  {
      std::cout << "destructor called\n";
  }

  Demo& operator= (Demo obj)
  {
      std::cout << "copy assignment operator called\n";
  }
};

int main()
{
    Demo obj1;//I am expecting error here : no default constructor present as it is deprecated
    Demo obj2(obj1);
    return 0;
}

//output:

destructor called
destructor called

>Solution :

The quote talks about the implicitly-defined copy constructor, i.e. the implicit constructor of the form

Demo(const Demo&);

not the implicitly-defined default constructor, i.e. the constructor of the form

Demo();

The latter is what you are using in Demo obj1; and the quote doesn’t apply to it.

The line Demo obj2(obj1); should however generate a deprecation warning, because it does use the implicitly-declared copy constructor, which is deprecated since C++11.

However, the compilers seem to have decided to not warn about this deprecation in general. For example GCC requires -Wextra to emit it. Also, the deprecation has been around for a long time, so it might be questionable whether it will ever actually be removed. Nonetheless, a class declaring a copy assignment and/or destructor explicitly is almost always broken if it doesn’t also define a copy constructor explicitly.