{"ast_node_type":"variable","tokens":[{"end":64,"kind":"keyword","start":0,"text":"if"}]}
        if let &mir::Rvalue::Ref(region, kind, place) = rvalue {
    fn visit_rvalue(&mut self, rvalue: &mir::Rvalue<'tcx>, location: mir::Location) {
            // double-check that we already registered a BorrowData for this