`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
{
        if (a->GetCountWithAncestors() != b->GetCountWithAncestors())
            return a->GetCountWithAncestors() < b->GetCountWithAncestors();
        return CTxMemPool::CompareIteratorByHash()(a, b);
    }
};
typedef boost::multi_index_container<
    CTxMemPoolModifiedEntry,
    boost::multi_index::indexed_by<
        boost::multi_index::ordered_unique<
            modifiedentry_iter,
            CompareCTxMemPoolIter
        >,
        
        boost::multi_index::ordered_non_unique<
            
            boost::multi_index::tag<ancestor_score>,
            boost::multi_index::identity<CTxMemPoolModifiedEntry>,
            CompareModifiedEntry
        >
    >
> indexed_modified_transaction_set;
typedef indexed_modified_transaction_set::nth_index<0>::type::iterator modtxiter;
typedef indexed_modified_transaction_set::index<ancestor_score>::type::iterator modtxscoreiter;
struct update_for_parent_inclusion
{
    explicit update_for_parent_inclusion(CTxMemPool::txiter it) : iter(it) {}