TreeMaker make_at(DiagnosticPosition pos){
  make_pos=pos;
  return make.at(pos);
}

TreeMaker make_at ( DiagnosticPosition pos ) { make_pos = pos ; return make . at ( pos ) ; }
equivalent to make . at ( pos . getstartposition ( ) ) with side effect of caching pos as make_pos , for use in diagnostics .
