{"ast_node_type":"other","tokens":[{"end":57,"kind":"keyword","start":0,"text":")"}]}
    ) -> (Vec<NeededMigration>, MigrationWarningReason) {
        min_captures: Option<&ty::RootVariableMinCaptureList<'tcx>>,
        let Some(upvars) = self.tcx.upvars_mentioned(closure_def_id) else {