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
```
{"fee_rate", UniValueType(UniValue::VNUM)},
                {"replaceable", UniValueType(UniValue::VBOOL)},
                {"estimate_mode", UniValueType(UniValue::VSTR)},
            },
            true, true);
        if (options.exists("confTarget") && options.exists("conf_target")) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "confTarget and conf_target options should not both be set. Use conf_target (confTarget is deprecated).");
        }
        auto conf_target = options.exists("confTarget") ? options["confTarget"] : options["conf_target"];
        if (!conf_target.isNull()) {
            if (options.exists("fee_rate")) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot specify both conf_target and fee_rate. Please provide either a confirmation target in blocks for automatic fee estimation, or an explicit fee rate.");
            }
        } else if (options.exists("fee_rate")) {
            CFeeRate fee_rate(AmountFromValue(options["fee_rate"]));
            if (fee_rate <= CFeeRate(0)) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid fee_rate %s (must be greater than 0)", fee_rate.ToString()));
            }
            coin_control.m_feerate = fee_rate;
        }
        if (options.exists("replaceable")) {
            coin_control.m_signal_bip125_rbf = options["replaceable"].get_bool();
        }
        SetFeeEstimateMode(pwallet, coin_control, options["estimate_mode"], conf_target);
    }
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    LOCK(pwallet->cs_wallet);
    EnsureWalletIsUnlocked(pwallet);