util: Properly handle -noincludeconf on command line

This bug was introduced in commit
fad0867d6ab9430070aa7d60bf7617a6508e0586.

Unit test
Co-Authored-By: Russell Yanofsky <russ@yanofsky.org>

Github-Pull: #22137
Rebased-From: fa910b47656d0e69cccb1f31804f2b11aa45d053

2 files changed, 26 insertions, 4 deletions

diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 010b6adf1f..cc58f64555 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -318,6 +318,25 @@ BOOST_FIXTURE_TEST_CASE(util_CheckValue, CheckValueTest)
     CheckValue(M::ALLOW_ANY, "-value=abc", Expect{"abc"}.String("abc").Int(0).Bool(false).List({"abc"}));
 }
 
+struct NoIncludeConfTest {
+    std::string Parse(const char* arg)
+    {
+        TestArgsManager test;
+        test.SetupArgs({{"-includeconf", ArgsManager::ALLOW_ANY}});
+        std::array<const char*, 2> argv{"ignored", arg};
+        std::string error;
+        (void)test.ParseParameters(argv.size(), argv.data(), error);
+        return error;
+    }
+};
+
+BOOST_FIXTURE_TEST_CASE(util_NoIncludeConf, NoIncludeConfTest)
+{
+    BOOST_CHECK_EQUAL(Parse("-noincludeconf"), "");
+    BOOST_CHECK_EQUAL(Parse("-includeconf"), "-includeconf cannot be used from commandline; -includeconf=\"\"");
+    BOOST_CHECK_EQUAL(Parse("-includeconf=file"), "-includeconf cannot be used from commandline; -includeconf=\"file\"");
+}
+
 BOOST_AUTO_TEST_CASE(util_ParseParameters)
 {
     TestArgsManager testArgs;
diff --git a/src/util/system.cpp b/src/util/system.cpp
index a21d58a19d..0d8b669b79 100644
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -336,11 +336,14 @@ bool ArgsManager::ParseParameters(int argc, const char* const argv[], std::strin
         m_settings.command_line_options[key].push_back(value);
     }
 
-    // we do not allow -includeconf from command line
+    // we do not allow -includeconf from command line, only -noincludeconf
     if (auto* includes = util::FindKey(m_settings.command_line_options, "includeconf")) {
-        const auto& include{*util::SettingsSpan(*includes).begin()}; // pick first value as example
-        error = "-includeconf cannot be used from commandline; -includeconf=" + include.write();
-        return false;
+        const util::SettingsSpan values{*includes};
+        // Range may be empty if -noincludeconf was passed
+        if (!values.empty()) {
+            error = "-includeconf cannot be used from commandline; -includeconf=" + values.begin()->write();
+            return false; // pick first value as example
+        }
     }
     return true;
 }