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
```
pwallet->BlockUntilSyncedToCurrentChain();
    LOCK(pwallet->cs_wallet);
    return ValueFromAmount(GetReceived(*pwallet, request.params,  false));
},
    };
}
static RPCHelpMan getreceivedbylabel()
{
    return RPCHelpMan{"getreceivedbylabel",
                "\nReturns the total amount received by addresses with <label> in transactions with at least [minconf] confirmations.\n",
                {
                    {"label", RPCArg::Type::STR, RPCArg::Optional::NO, "The selected label, may be the default label using \"\"."},
                    {"minconf", RPCArg::Type::NUM,  "1", "Only include transactions confirmed at least this many times."},
                },
                RPCResult{
                    RPCResult::Type::STR_AMOUNT, "amount", "The total amount in " + CURRENCY_UNIT + " received for this label."
                },
                RPCExamples{
            "\nAmount received by the default label with at least 1 confirmation\n"
            + HelpExampleCli("getreceivedbylabel", "\"\"") +
            "\nAmount received at the tabby label including unconfirmed amounts with zero confirmations\n"
            + HelpExampleCli("getreceivedbylabel", "\"tabby\" 0") +
            "\nThe amount with at least 6 confirmations\n"
            + HelpExampleCli("getreceivedbylabel", "\"tabby\" 6") +
            "\nAs a JSON-RPC call\n"
            + HelpExampleRpc("getreceivedbylabel", "\"tabby\", 6")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue