{"ast_node_type":"other","tokens":[{"end":50,"kind":"keyword","start":0,"text":"//"}]}
    // Any BCB not in this set was optimized away.
    // Scan through the final MIR to see which BCBs survived MIR opts.
    let mut bcbs_seen = DenseBitSet::new_empty(fn_cov_info.priority_list.len());