Have this warning while building current master (0bd4929cd00e91bf4137f43b097cd62f72f503e4) on one test machine.
```
wallet/rpcwallet.cpp: In function 'rescanblockchain()::<lambda(const RPCHelpMan&, const JSONRPCRequest&)>':
wallet/rpcwallet.cpp:3596:19: warning: '*((void*)& stop_height +4)' may be used uninitialized in this function [-Wmaybe-uninitialized]
 3596 |     Optional<int> stop_height;
      |                   ^~~~~~~~~~~
```
```
$ gcc --version
gcc (Gentoo 9.2.0-r2 p3) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ uname -a
Linux red-box 4.19.72-gentoo #2 SMP Sun Sep 22 03:00:01 EEST 2019 x86_64 Intel(R) Pentium(R) CPU N3710 @ 1.60GHz GenuineIntel GNU/Linux
```
UniValue transactions(UniValue::VARR);
            if (it != mapTally.end())
            {
                for (const uint256& _item : (*it).second.txids)
                {
                    transactions.push_back(_item.GetHex());
                }
            }
            obj.pushKV("txids", transactions);
            ret.push_back(obj);
        }
    }
    if (by_label)
    {
        for (const auto& entry : label_tally)
        {
            CAmount nAmount = entry.second.nAmount;
            int nConf = entry.second.nConf;
            UniValue obj(UniValue::VOBJ);
            if (entry.second.fIsWatchonly)
                obj.pushKV("involvesWatchonly", true);
            obj.pushKV("amount",        ValueFromAmount(nAmount));
            obj.pushKV("confirmations", (nConf == std::numeric_limits<int>::max() ? 0 : nConf));
            obj.pushKV("label",         entry.first);
            ret.push_back(obj);
        }
    }
    return ret;
}
static RPCHelpMan listreceivedbyaddress()