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#include <iostream>
using namespace std;
 
template<class T>
class MyVar
{
    int x;
 
public:
	friend void printVar(const MyVar & var);
	friend void scanVar(MyVar & var);
};
 
template<class T>
void printVar(const MyVar<T> & var) {
	std::cout << var.x << std::endl;
}
template<class T>
void scanVar(MyVar<T> & var) {
	std::cin >> var.x;
}
 
struct Foo {};
int main() {
	// your code goes here
	MyVar<Foo> a;
	scanVar(a);
	printVar(a);
	return 0;
}

prog.cpp:10:40: warning: friend declaration 'void printVar(const MyVar<T>&)' declares a non-template function [-Wnon-template-friend]
  friend void printVar(const MyVar & var);
                                        ^
prog.cpp:10:40: note: (if this is not what you intended, make sure the function template has already been declared and add <> after the function name here) 
prog.cpp:11:33: warning: friend declaration 'void scanVar(MyVar<T>&)' declares a non-template function [-Wnon-template-friend]
  friend void scanVar(MyVar & var);
                                 ^
/home/POhCBl/ccjI3ner.o: In function `main':
prog.cpp:(.text.startup+0x17): undefined reference to `scanVar(MyVar<Foo>&)'
prog.cpp:(.text.startup+0x1f): undefined reference to `printVar(MyVar<Foo> const&)'
collect2: error: ld returned 1 exit status

Standard output is empty