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
```
const auto it = pwallet->mapWallet.find(outpt.hash);
        if (it == pwallet->mapWallet.end()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, unknown transaction");
        }
        const CWalletTx& trans = it->second;
        if (outpt.n >= trans.tx->vout.size()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, vout index out of bounds");
        }
        if (pwallet->IsSpent(outpt.hash, outpt.n)) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, expected unspent output");
        }
        const bool is_locked = pwallet->IsLockedCoin(outpt.hash, outpt.n);
        if (fUnlock && !is_locked) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, expected locked output");
        }
        if (!fUnlock && is_locked) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, output already locked");
        }
        outputs.push_back(outpt);
    }
    
    for (const COutPoint& outpt : outputs) {
        if (fUnlock) pwallet->UnlockCoin(outpt);
        else pwallet->LockCoin(outpt);
    }
    return true;
},
    };
}
static RPCHelpMan listlockunspent()