ostream operator can easily enter infinite loop

[tmadlener]

It is easily possible to enter an infinite loop (and a subsequent core dump) using the ostream operator if OneToManyRelations are used like they are e.g. in ExampleMC (only the important parts here):

ExampleMC:
  OneToManyRelations:
    - ExampleMC parents
    - ExampleMC daughters

Properly setting mother/daughter relations in this case

ExampleMC mcp1;
ExampleMC mcp2;

mcp1.adddaughters(mcp2);
mcp2.adddaughters(mcp1);

will lead to an infinite loop in the ostream operator, since that is generated to be

std::ostream& operator<<( std::ostream& o,const ConstExampleMC& value ){
  o << " id : " << value.id() << std::endl ;
  o << " parents : " ;
  for(unsigned i=0,N=value.parents_size(); i<N ; ++i)
    o << value.parents(i) << " " ; // the problem is here
  o << std::endl ;
  o << " daughters ): " ;
  for(unsigned i=0,N=value.daughters_size(); i<N ; ++i)
    o << value.daughters(i) << " " ; // and also here
  o << std::endl ;
  return o ;
}

and is thus calling itself over and over again if such a circular relation is found.