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
```
}
    
    std::string label;
    if (!request.params[0].isNull())
        label = LabelFromValue(request.params[0]);
    OutputType output_type = pwallet->m_default_address_type;
    if (!request.params[1].isNull()) {
        if (!ParseOutputType(request.params[1].get_str(), output_type)) {
            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[1].get_str()));
        }
    }
    CTxDestination dest;
    std::string error;
    if (!pwallet->GetNewDestination(output_type, label, dest, error)) {
        throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, error);
    }
    return EncodeDestination(dest);
},
    };
}
static RPCHelpMan getrawchangeaddress()
{
    return RPCHelpMan{"getrawchangeaddress",
                "\nReturns a new Bitcoin address, for receiving change.\n"
                "This is for use with raw transactions, NOT normal use.\n",
                {
                    {"address_type", RPCArg::Type::STR,  "set by -changetype", "The address type to use. Options are \"legacy\", \"p2sh-segwit\", and \"bech32\"."},
                },
                RPCResult{
                    RPCResult::Type::STR, "address", "The address"