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
```
bool can_avoid_reuse = pwallet->IsWalletFlagSet(WALLET_FLAG_AVOID_REUSE);
    bool avoid_reuse = param.isNull() ? can_avoid_reuse : param.get_bool();
    if (avoid_reuse && !can_avoid_reuse) {
        throw JSONRPCError(RPC_WALLET_ERROR, "wallet does not have the \"avoid reuse\" feature enabled");
    }
    return avoid_reuse;
}
/** Used by RPC commands that have an include_watchonly parameter.
 *  We default to true for watchonly wallets if include_watchonly isn't
 *  explicitly set.
 */
static bool ParseIncludeWatchonly(const UniValue& include_watchonly, const CWallet& pwallet)
{
    if (include_watchonly.isNull()) {
        
        return pwallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
    }
    
    return include_watchonly.get_bool();
}
bool HaveKey(const SigningProvider& wallet, const CKey& key)
{
    CKey key2;
    key2.Set(key.begin(), key.end(), !key.IsCompressed());
    return wallet.HaveKey(key.GetPubKey().GetID()) || wallet.HaveKey(key2.GetPubKey().GetID());
}
bool GetWalletNameFromJSONRPCRequest(const JSONRPCRequest& request, std::string& wallet_name)