Fix -Wunreachable-code-loop-increment warning #19017

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.

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:

./autogen.sh
./configure CXXFLAGS="-Wunreachable-code-loop-increment"
make check

Does this issue have a solution, or is this a false positive?

Does this issue have a solution, or is this a false positive?

We are currently only reporting the first configuration issue encountered.

I guess the intention was something along the lines of:

diff --git a/src/init.cpp b/src/init.cpp
index 3b97ba08d..9cb446e14 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -967,7 +967,10 @@ bool AppInitParameterInteraction()
     // on the command line or in this network's section of the config file.
     std::string network = gArgs.GetChainName();
     for (const auto& arg : gArgs.GetUnsuitableSectionOnlyArgs()) {
-        return InitError(strprintf(_("Config setting for %s only applied on %s network when in [%s] section."), arg, network, network));
+        InitError(strprintf(_("Config setting for %s only applied on %s network when in [%s] section."), arg, network, network));
+    }
+    if (!gArgs.GetUnsuitableSectionOnlyArgs().empty()) {
+        return false;
     }

     // Warn if unrecognized section name are present in the config file.

InitError should only be called once, otherwise we will end up with the javascript popup hell from 2005.

I think it wants to set a cookie

Back to topic: If someone wants to fix this, the solution is probably to collect all error messages in the loop and then send out one (and only one) InitError. Should be easy to fix unless I am missing something.

I can have a look at this.

Back to topic: If someone wants to fix this, the solution is probably to collect all error messages in the loop and then send out one (and only one) InitError.

While we're at it, should we also fix the InitWarning loop directly below to avoid pop-up hell there? https://github.com/bitcoin/bitcoin/blob/aa8d76806c74a51ec66e5004394fe9ea8ff0fac4/src/init.cpp#L975-L977

@jonathanschoeller Good catch. Please fix all issues you can find :)