There was a circular dependency between Littrack and CbmRichReco. The problem only shows up when linking an executable. The dependency could be resolved by moving some of the rich code into the directory core/detectors/rich and splitting the littrack library into two parts. The first library (Littrack) contains everything beside the littrack QA classes and the second one (LittrackQA) contains only the QA code. Those files moved from reco/detectors/rich had no dependencies to reco or sim.