#include <iostream>
using namespace std;
 
#define FWD(v) \
    std::forward< \
        typename std::remove_const<\
        typename std::remove_reference<\
        decltype(v)>::type>::type>(v)
 
void foo(int& a) { cout << "ref" << endl; }
void foo(const int& a) { cout << "cref" << endl; }
 
template <typename T>
void call_foo(T&& t) { foo(FWD(t)); }
 
int main() {
	int a = 10;
	foo(10);
	foo(a);
 
	call_foo(10);
	call_foo(a);
	return 0;
}
 

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