std::unordered_set<ObjectRepresentation*> incompletePieces;

while (incompletePieces.size()){
        for (auto containedPiece : incompletePieces){ //Warning at this line that loop will run at most once
            //  .... doing some stuff with the contained piece
            incompletePieces.erase(containedPiece);

                    break;
        }
    }