c++referenceconstants

Pass same object as const and non-const reference

The following code compiles with g++ v4.8.1 and outputs 45, but is its compilation guaranteed based on the standard? Would other compilers complain?

#include <iostream>
#include <vector>

void test(const std::vector<int>& a, std::vector<int>& b) {
  b[0] = 45;
}

int main() {
  std::vector<int> v(1,0);
  test(v, v);
  std::cout << v[0] << std::endl;
}

I understand that there's nothing inherently wrong with the function definition, but when calling test with the same object, v, I somewhat expected a warning that I was passing a single object as both a const and non-const reference.

Solution

  • There is no problem becuase the compiler consideres these two parameters as different references. To understand the code consider the following example

    int i = 10;
const int &cr = i;
int &r = i;

r = 20;

std::cout << cr << std::endl;