{"ast_node_type":"variable","tokens":[{"end":72,"kind":"keyword","start":0,"text":"let"}]}
        let res = self.cx.typeck_results().qpath_res(qpath, pat_hir_id);
    ) -> Result<VariantIdx, Cx::Error> {
        let ty = self.cx.typeck_results().node_type(pat_hir_id);