#include <iostream>
#include <string>

template <typename ... TParent>
class Parent {
	public:
    
	class Child {
	public:
	    template <typename ... T>
	    void childDummyFunction() {
	    }
	};
	
	template <typename ... TFunctionParameters>
	void parentFunction() {
		Child child;
		child.childDummyFunction<TFunctionParameters...>();		
	}
};

int main()
{
    Parent<int> sys;
    
    sys.parentFunction<float>();
    
  std::cout << "Hello, " << "!\n";
}

/*
main.cpp: In member function ‘void Parent<TParent>::parentFunction()’:
main.cpp:19:47: error: expected primary-expression before ‘...’ token
   child.childDummyFunction<TFunctionParameters...>();  
                                               ^~~
main.cpp:19:47: error: expected ‘;’ before ‘...’ token
*/