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
```
throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletlock was called.");
    }
    pwallet->Lock();
    pwallet->nRelockTime = 0;
    return NullUniValue;
},
    };
}
static RPCHelpMan encryptwallet()
{
    return RPCHelpMan{"encryptwallet",
                "\nEncrypts the wallet with 'passphrase'. This is for first time encryption.\n"
                "After this, any calls that interact with private keys such as sending or signing \n"
                "will require the passphrase to be set prior the making these calls.\n"
                "Use the walletpassphrase call for this, and then walletlock call.\n"
                "If the wallet is already encrypted, use the walletpassphrasechange call.\n",
                {
                    {"passphrase", RPCArg::Type::STR, RPCArg::Optional::NO, "The pass phrase to encrypt the wallet with. It must be at least 1 character, but should be long."},
                },
                RPCResult{RPCResult::Type::STR, "", "A string with further instructions"},
                RPCExamples{
            "\nEncrypt your wallet\n"
            + HelpExampleCli("encryptwallet", "\"my pass phrase\"") +
            "\nNow set the passphrase to use the wallet, such as for signing or sending bitcoin\n"
            + HelpExampleCli("walletpassphrase", "\"my pass phrase\"") +
            "\nNow we can do something like sign\n"
            + HelpExampleCli("signmessage", "\"address\" \"test message\"") +
            "\nNow lock the wallet again by removing the passphrase\n"
            + HelpExampleCli("walletlock", "") +
            "\nAs a JSON-RPC call\n"