{"ast_node_type":"variable","tokens":[{"end":16,"kind":"keyword","start":0,"text":"let"}]}
    let report =
        patterns.iter().map(|pat| MatchArm { pat, has_guard: false, arm_data: () }).collect();
        compute_match_usefulness(arms.as_slice(), ty, PlaceValidity::ValidOnly, usize::MAX, false)