Overload Resolution Trap

#include <iostream>
// using namespace std;

// define void foo(int x) -> prints "int overload"
void foo(int x){
    std::cout << "int overload\n" ;
}

// define void foo(int* p) -> prints "int* overload"
void foo(int *p){
    std::cout << "int* overload\n" ;
}

int main() {
    foo(0);         
    foo(nullptr);   
    return 0;
}

standard syntax