c++ - Why crtp works for structs and not for class? -

let's consider following code:

template<typename t> struct base{  }; struct derived: base<derived>{ }; int main() {     base<derived>* base_ptr = new derived(); } 

and works, mean compiled. , same version of class:

template<typename t> class base{  }; class derived: base<derived>{ }; int main() {     base<derived>* base_ptr = new derived();  //error  ‘base<derived>’ inaccessible base of ‘derived’ } 

because struct default access base classes public, , class it's private.

use

class derived: public base<derived>{                ^^^^^^ 

to make equivalent first example.

this has nothing crtp, same error without crtp:

class base { }; class derived : base { }; base* base_ptr = new derived();