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
```
obj.pushKV("script", GetTxnOutputType(which_type));
        obj.pushKV("hex", HexStr(subscript));
        CTxDestination embedded;
        if (ExtractDestination(subscript, embedded)) {
            
            UniValue subobj(UniValue::VOBJ);
            UniValue detail = DescribeAddress(embedded);
            subobj.pushKVs(detail);
            UniValue wallet_detail = boost::apply_visitor(*this, embedded);
            subobj.pushKVs(wallet_detail);
            subobj.pushKV("address", EncodeDestination(embedded));
            subobj.pushKV("scriptPubKey", HexStr(subscript));
            
            if (subobj.exists("pubkey")) obj.pushKV("pubkey", subobj["pubkey"]);
            obj.pushKV("embedded", std::move(subobj));
        } else if (which_type == TxoutType::MULTISIG) {
            
            
            obj.pushKV("sigsrequired", solutions_data[0][0]);
            UniValue pubkeys(UniValue::VARR);
            for (size_t i = 1; i < solutions_data.size() - 1; ++i) {
                CPubKey key(solutions_data[i].begin(), solutions_data[i].end());
                pubkeys.push_back(HexStr(key));
            }
            obj.pushKV("pubkeys", std::move(pubkeys));
        }
    }
    explicit DescribeWalletAddressVisitor(const SigningProvider* _provider) : provider(_provider) {}
    UniValue operator()(const CNoDestination& dest) const { return UniValue(UniValue::VOBJ); }
    UniValue operator()(const PKHash& pkhash) const