我就是程序员 第一季 第一期

first.cpp

#include <map>

class R {
};

class S {
  R &m_r;

public:
  S(R &r): m_r(r) {
  }
};

void InsertIfNotExists(std::map<int, S> &m, int i, R &r) {
  if (m.find(i) == m.end())
    m[i] = S(r);
}

// Compiler: line 16: error C2280: 'S &S::operator=(const S &)': attempting to reference a deleted function
// Please fix this code.