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
```
HelpExampleCli("settxfee", "0.00001")
            + HelpExampleRpc("settxfee", "0.00001")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    if (!wallet) return NullUniValue;
    CWallet* const pwallet = wallet.get();
    LOCK(pwallet->cs_wallet);
    CAmount nAmount = AmountFromValue(request.params[0]);
    CFeeRate tx_fee_rate(nAmount, 1000);
    CFeeRate max_tx_fee_rate(pwallet->m_default_max_tx_fee, 1000);
    if (tx_fee_rate == CFeeRate(0)) {
        
    } else if (tx_fee_rate < pwallet->chain().relayMinFee()) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than min relay tx fee (%s)", pwallet->chain().relayMinFee().ToString()));
    } else if (tx_fee_rate < pwallet->m_min_fee) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than wallet min fee (%s)", pwallet->m_min_fee.ToString()));
    } else if (tx_fee_rate > max_tx_fee_rate) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be more than wallet max tx fee (%s)", max_tx_fee_rate.ToString()));
    }
    pwallet->m_pay_tx_fee = tx_fee_rate;
    return true;
},
    };
}
static RPCHelpMan getbalances()
{
    return RPCHelpMan{
        "getbalances",