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 RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    std::string wallet_name;
    if (GetWalletNameFromJSONRPCRequest(request, wallet_name)) {
        if (!request.params[0].isNull()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot unload the requested wallet");
        }
    } else {
        wallet_name = request.params[0].get_str();
    }
    std::shared_ptr<CWallet> wallet = GetWallet(wallet_name);
    if (!wallet) {
        throw JSONRPCError(RPC_WALLET_NOT_FOUND, "Requested wallet does not exist or is not loaded");
    }
    
    
    
    std::vector<bilingual_str> warnings;
    Optional<bool> load_on_start = request.params[1].isNull() ? nullopt : Optional<bool>(request.params[1].get_bool());
    if (!RemoveWallet(wallet, load_on_start, warnings)) {
        throw JSONRPCError(RPC_MISC_ERROR, "Requested wallet already unloaded");
    }
    UnloadWallet(std::move(wallet));
    UniValue result(UniValue::VOBJ);
    result.pushKV("warning", Join(warnings, Untranslated("\n")).original);
    return result;
},
    };
}
static RPCHelpMan listunspent()