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
```
if (!feebumper::SignTransaction(*pwallet, mtx)) {
            throw JSONRPCError(RPC_WALLET_ERROR, "Can't sign transaction.");
        }
        uint256 txid;
        if (feebumper::CommitTransaction(*pwallet, hash, std::move(mtx), errors, txid) != feebumper::Result::OK) {
            throw JSONRPCError(RPC_WALLET_ERROR, errors[0].original);
        }
        result.pushKV("txid", txid.GetHex());
    } else {
        PartiallySignedTransaction psbtx(mtx);
        bool complete = false;
        const TransactionError err = pwallet->FillPSBT(psbtx, complete, SIGHASH_ALL, false , true );
        CHECK_NONFATAL(err == TransactionError::OK);
        CHECK_NONFATAL(!complete);
        CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
        ssTx << psbtx;
        result.pushKV("psbt", EncodeBase64(ssTx.str()));
    }
    result.pushKV("origfee", ValueFromAmount(old_fee));
    result.pushKV("fee", ValueFromAmount(new_fee));
    UniValue result_errors(UniValue::VARR);
    for (const bilingual_str& error : errors) {
        result_errors.push_back(error.original);
    }
    result.pushKV("errors", result_errors);
    return result;
},
    };
}
static RPCHelpMan bumpfee() { return bumpfee_helper("bumpfee"); }