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
```
if (options.exists("changePosition") || options.exists("change_position")) {
            change_position = (options.exists("change_position") ? options["change_position"] : options["changePosition"]).get_int();
        }
        if (options.exists("change_type")) {
            if (options.exists("changeAddress") || options.exists("change_address")) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot specify both change address and address type options");
            }
            OutputType out_type;
            if (!ParseOutputType(options["change_type"].get_str(), out_type)) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown change type '%s'", options["change_type"].get_str()));
            }
            coinControl.m_change_type.emplace(out_type);
        }
        const UniValue include_watching_option = options.exists("include_watching") ? options["include_watching"] : options["includeWatching"];
        coinControl.fAllowWatchOnly = ParseIncludeWatchonly(include_watching_option, *pwallet);
        if (options.exists("lockUnspents") || options.exists("lock_unspents")) {
            lockUnspents = (options.exists("lock_unspents") ? options["lock_unspents"] : options["lockUnspents"]).get_bool();
        }
        if (options.exists("feeRate"))
        {
            if (options.exists("conf_target")) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot specify both conf_target and feeRate");
            }
            if (options.exists("estimate_mode")) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot specify both estimate_mode and feeRate");
            }
            coinControl.m_feerate = CFeeRate(AmountFromValue(options["feeRate"]));
            coinControl.fOverrideFeeRate = true;
        }
        if (options.exists("subtractFeeFromOutputs") || options.exists("subtract_fee_from_outputs") )