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
```
{ "wallet",             "listreceivedbylabel",              &listreceivedbylabel,           {"minconf","include_empty","include_watchonly"} },
    { "wallet",             "listsinceblock",                   &listsinceblock,                {"blockhash","target_confirmations","include_watchonly","include_removed"} },
    { "wallet",             "listtransactions",                 &listtransactions,              {"label|dummy","count","skip","include_watchonly"} },
    { "wallet",             "listunspent",                      &listunspent,                   {"minconf","maxconf","addresses","include_unsafe","query_options"} },
    { "wallet",             "listwalletdir",                    &listwalletdir,                 {} },
    { "wallet",             "listwallets",                      &listwallets,                   {} },
    { "wallet",             "loadwallet",                       &loadwallet,                    {"filename", "load_on_startup"} },
    { "wallet",             "lockunspent",                      &lockunspent,                   {"unlock","transactions"} },
    { "wallet",             "removeprunedfunds",                &removeprunedfunds,             {"txid"} },
    { "wallet",             "rescanblockchain",                 &rescanblockchain,              {"start_height", "stop_height"} },
    { "wallet",             "send",                             &send,                          {"outputs","conf_target","estimate_mode","options"} },
    { "wallet",             "sendmany",                         &sendmany,                      {"dummy","amounts","minconf","comment","subtractfeefrom","replaceable","conf_target","estimate_mode","verbose"} },
    { "wallet",             "sendtoaddress",                    &sendtoaddress,                 {"address","amount","comment","comment_to","subtractfeefromamount","replaceable","conf_target","estimate_mode","avoid_reuse","verbose"} },
    { "wallet",             "sethdseed",                        &sethdseed,                     {"newkeypool","seed"} },
    { "wallet",             "setlabel",                         &setlabel,                      {"address","label"} },
    { "wallet",             "settxfee",                         &settxfee,                      {"amount"} },
    { "wallet",             "setwalletflag",                    &setwalletflag,                 {"flag","value"} },
    { "wallet",             "signmessage",                      &signmessage,                   {"address","message"} },
    { "wallet",             "signrawtransactionwithwallet",     &signrawtransactionwithwallet,  {"hexstring","prevtxs","sighashtype"} },
    { "wallet",             "unloadwallet",                     &unloadwallet,                  {"wallet_name", "load_on_startup"} },
    { "wallet",             "upgradewallet",                    &upgradewallet,                 {"version"} },
    { "wallet",             "walletcreatefundedpsbt",           &walletcreatefundedpsbt,        {"inputs","outputs","locktime","options","bip32derivs"} },
    { "wallet",             "walletlock",                       &walletlock,                    {} },
    { "wallet",             "walletpassphrase",                 &walletpassphrase,              {"passphrase","timeout"} },
    { "wallet",             "walletpassphrasechange",           &walletpassphrasechange,        {"oldpassphrase","newpassphrase"} },
    { "wallet",             "walletprocesspsbt",                &walletprocesspsbt,             {"psbt","sign","sighashtype","bip32derivs"} },
};
    return MakeSpan(commands);
}