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
```
result.pushKV("fee", ValueFromAmount(fee));
    result.pushKV("changepos", change_position);
    return result;
},
    };
}
static RPCHelpMan upgradewallet()
{
    return RPCHelpMan{"upgradewallet",
        "\nUpgrade the wallet. Upgrades to the latest version if no version number is specified\n"
        "New keys may be generated and a new wallet backup will need to be made.",
        {
            {"version", RPCArg::Type::NUM,  strprintf("%d", FEATURE_LATEST), "The version number to upgrade to. Default is the latest wallet version"}
        },
        RPCResult{
            RPCResult::Type::OBJ, "", "",
            {
                {RPCResult::Type::STR, "error",  true, "Error message (if there is one)"}
            },
        },
        RPCExamples{
            HelpExampleCli("upgradewallet", "169900")
            + HelpExampleRpc("upgradewallet", "169900")
        },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    if (!wallet) return NullUniValue;
    CWallet* const pwallet = wallet.get();
    RPCTypeCheck(request.params, {UniValue::VNUM}, true);