https://github.com/bitcoin/bitcoin/blob/68f3c7eb080e461cfeac37f8db7034fe507241d0/src/prevector.h#L152-L158

I'm opening an issue as its fix is too tiny to become a pull request.

Can be solved by renaming the struct to
```c
     struct indirect_contents { 
         size_type capacity; 
         char* indirect; 
     }; 
```
{
    if (!res.empty()) res += ", ";
    res += warn;
}
void static UpdateTip(const CBlockIndex* pindexNew, const CChainParams& chainParams)
    EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
    
    mempool.AddTransactionsUpdated(1);
    {
        LOCK(g_best_block_mutex);
        g_best_block = pindexNew->GetBlockHash();
        g_best_block_cv.notify_all();
    }
    std::string warningMessages;
    if (!::ChainstateActive().IsInitialBlockDownload())
    {
        int nUpgraded = 0;
        const CBlockIndex* pindex = pindexNew;
        for (int bit = 0; bit < VERSIONBITS_NUM_BITS; bit++) {
            WarningBitsConditionChecker checker(bit);
            ThresholdState state = checker.GetStateFor(pindex, chainParams.GetConsensus(), warningcache[bit]);
            if (state == ThresholdState::ACTIVE || state == ThresholdState::LOCKED_IN) {
                const std::string strWarning = strprintf(_("Warning: unknown new rules activated (versionbit %i)").translated, bit);
                if (state == ThresholdState::ACTIVE) {
                    DoWarning(strWarning);
                } else {
                    AppendWarning(warningMessages, strWarning);
                }
            }