In #19015 it's been suggested that we add some new compiler warnings to our build. Some of these, such as `-Wunreachable-code-loop-increment`, generate warnings. We'll likely want to fix these up if we're going to turn these warnings on.

```bash
init.cpp:969:5: warning: loop will run at most once (loop increment never executed) [-Wunreachable-code-loop-increment]
    for (const auto& arg : gArgs.GetUnsuitableSectionOnlyArgs()) {
    ^~~
1 warning generated.
```

https://github.com/bitcoin/bitcoin/blob/aa8d76806c74a51ec66e5004394fe9ea8ff0fac4/src/init.cpp#L968-L972

If you want to build master, with `-Wunreachable-code-loop-increment`, you can use something like this:
```bash
./autogen.sh
./configure CXXFLAGS="-Wunreachable-code-loop-increment"
make check
```
if (net == NET_UNROUTABLE)
                return InitError(strprintf(_("Unknown network specified in -onlynet: '%s'"), snet));
            nets.insert(net);
        }
        for (int n = 0; n < NET_MAX; n++) {
            enum Network net = (enum Network)n;
            if (!nets.count(net))
                SetReachable(net, false);
        }
    }
    
    fNameLookup = gArgs.GetBoolArg("-dns", DEFAULT_NAME_LOOKUP);
    bool proxyRandomize = gArgs.GetBoolArg("-proxyrandomize", DEFAULT_PROXYRANDOMIZE);
    
    
    std::string proxyArg = gArgs.GetArg("-proxy", "");
    SetReachable(NET_ONION, false);
    if (proxyArg != "" && proxyArg != "0") {
        CService proxyAddr;
        if (!Lookup(proxyArg, proxyAddr, 9050, fNameLookup)) {
            return InitError(strprintf(_("Invalid -proxy address or hostname: '%s'"), proxyArg));
        }
        proxyType addrProxy = proxyType(proxyAddr, proxyRandomize);
        if (!addrProxy.IsValid())
            return InitError(strprintf(_("Invalid -proxy address or hostname: '%s'"), proxyArg));
        SetProxy(NET_IPV4, addrProxy);
        SetProxy(NET_IPV6, addrProxy);
        SetProxy(NET_ONION, addrProxy);
        SetNameProxy(addrProxy);