Question about an example from rule 9-3-1

[dg1980]

Maybe this extended and commented sample answers your question:

Code:

#include

namespace nMISRA
{
  class C {
  public:
    C ( int32_t &b_ ) : b( b_ ) { }

    int32_t *getB () const
    {
      return &b;  // Non-compliant
    }
    int32_t getState(void) const{return b;}
  private:
    int32_t &b;
  };
}

int32_t main(void)
{
  int32_t ret = 0;
  int32_t state = 0;
  nMISRA::C c(state);
  *c.getB() = 1;// const member changing the state of the object, triggering error condition below
  if (c.getState() != 0)
  {
    ret = -1;// error
  }
  return ret;
}