`CompareModifiedEntry`, as used in

https://github.com/bitcoin/bitcoin/blob/3c098a8aa0780009c11b66b1a5d488a928629ebf/src/miner.h#L97-L112

will trigger a compile-time error in many `const` operations of index #1 of `indexed_modified_transaction_set` because `CompareModifiedEntry::operator()` is not `const`.

Most likely related to:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=224129
void UpdateEntryForAncestors(txiter it, const setEntries &setAncestors);
    /** For each transaction being removed, update ancestors and any direct children.
      * If updateDescendants is true, then also update in-mempool descendants'
      * ancestor state. */
    void UpdateForRemoveFromMempool(const setEntries &entriesToRemove, bool updateDescendants);
    
    void UpdateChildrenForRemoval(txiter entry);
    /** Before calling removeUnchecked for a given transaction,
     *  UpdateForRemoveFromMempool must be called on the entire (dependent) set
     *  of transactions being removed at the same time.  We use each
     *  CTxMemPoolEntry's setMemPoolParents in order to walk ancestors of a
     *  given transaction that is removed, so we can't remove intermediate
     *  transactions in a chain before we've updated all the state for the
     *  removal.
     */
    void removeUnchecked(txiter entry, MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN);
};
/** 
 * CCoinsView that brings transactions from a memorypool into view.
 * It does not check for spendings by memory pool transactions.
 * Instead, it provides access to all Coins which are either unspent in the
 * base CCoinsView, or are outputs from any mempool transaction!
 * This allows transaction replacement to work as expected, as you want to
 * have all inputs "available" to check signatures, and any cycles in the
 * dependency graph are checked directly in AcceptToMemoryPool.
 * It also allows you to sign a double-spend directly in signrawtransaction,
 * as long as the conflicting transaction is not yet confirmed.
 */
class CCoinsViewMemPool : public CCoinsViewBacked