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
```
flags |= WALLET_FLAG_DISABLE_PRIVATE_KEYS;
    }
    if (!request.params[2].isNull() && request.params[2].get_bool()) {
        flags |= WALLET_FLAG_BLANK_WALLET;
    }
    SecureString passphrase;
    passphrase.reserve(100);
    std::vector<bilingual_str> warnings;
    if (!request.params[3].isNull()) {
        passphrase = request.params[3].get_str().c_str();
        if (passphrase.empty()) {
            
            warnings.emplace_back(Untranslated("Empty string given as passphrase, wallet will not be encrypted."));
        }
    }
    if (!request.params[4].isNull() && request.params[4].get_bool()) {
        flags |= WALLET_FLAG_AVOID_REUSE;
    }
    if (!request.params[5].isNull() && request.params[5].get_bool()) {
#ifndef USE_SQLITE
        throw JSONRPCError(RPC_WALLET_ERROR, "Compiled without sqlite support (required for descriptor wallets)");
#endif
        flags |= WALLET_FLAG_DESCRIPTORS;
        warnings.emplace_back(Untranslated("Wallet is an experimental descriptor wallet"));
    }
    DatabaseOptions options;
    DatabaseStatus status;
    options.require_create = true;
    options.create_flags = flags;
    options.create_passphrase = passphrase;