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
```
},
                RPCExamples{
                    HelpExampleCli("listreceivedbyaddress", "")
            + HelpExampleCli("listreceivedbyaddress", "6 true")
            + HelpExampleRpc("listreceivedbyaddress", "6, true, true")
            + HelpExampleRpc("listreceivedbyaddress", "6, true, true, \"" + EXAMPLE_ADDRESS[0] + "\"")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    if (!wallet) return NullUniValue;
    const CWallet* const pwallet = wallet.get();
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    LOCK(pwallet->cs_wallet);
    return ListReceived(pwallet, request.params, false);
},
    };
}
static RPCHelpMan listreceivedbylabel()
{
    return RPCHelpMan{"listreceivedbylabel",
                "\nList received transactions by label.\n",
                {
                    {"minconf", RPCArg::Type::NUM,  "1", "The minimum number of confirmations before payments are included."},
                    {"include_empty", RPCArg::Type::BOOL,  "false", "Whether to include labels that haven't received any payments."},
                    {"include_watchonly", RPCArg::Type::BOOL,  "true for watch-only wallets, otherwise false", "Whether to include watch-only addresses (see 'importaddress')"},
                },
                RPCResult{