fix: allow controller setting integer to have a negative range

src/controllers/legacycontrollersettings.h

@@ -6,6 +6,23 @@
 #include "controllers/legacycontrollersettingslayout.h"
 #include "util/parented_ptr.h"
 
+namespace {
+template<class T>
+bool valid_range(T min, T max, T step) {
+    // Detecting overflow
+    VERIFY_OR_DEBUG_ASSERT(max + step > max) {
+        return false;
+    }
+    // Detecting overflow
+    VERIFY_OR_DEBUG_ASSERT(min - step < min) {
+        return false;
+    }
+
+    return (min <= 0 && min + step <= max) ||
+            (max >= 0 && max - step >= min);
+}
+} // namespace
+
 class QSpinBox;
 class QDoubleSpinBox;
 
@@ -263,7 +280,7 @@ class LegacyControllerNumberSetting
                 m_defaultValue >= m_minValue && m_savedValue >= m_minValue &&
                 m_editedValue >= m_minValue && m_defaultValue <= m_maxValue &&
                 m_savedValue <= m_maxValue && m_editedValue <= m_maxValue &&
-                m_stepValue > 0 && m_stepValue < m_maxValue;
+                m_stepValue > 0 && valid_range(m_minValue, m_maxValue, m_stepValue);
     }
 
     static AbstractLegacyControllerSetting* createFrom(const QDomElement& element) {

src/test/controller_mapping_settings_test.cpp

@@ -511,3 +511,38 @@ TEST_F(LegacyControllerMappingSettingsTest, discardDuplicateSettings) {
     ASSERT_EQ(settings.at(1)->value().toNumber(), 50);
     ASSERT_EQ(settings.at(2)->value().toString(), "myOptionValue1");
 }
+
+TEST_F(LegacyControllerMappingSettingsTest, handleNumberWithNegativeRange) {
+    QDomDocument doc;
+    QString dom;
+    QTextStream(&dom)
+            << QString(kValidInteger).arg("0", "-500", "0", "1");
+    doc.setContent(
+            QString("<?xml version=\"1.0\" "
+                    "encoding=\"utf-8\"?><MixxxControllerPreset><settings>%1</"
+                    "settings></MixxxControllerPreset>")
+                    .arg(dom));
+
+    auto pMapping = LegacyDummyMappingFileHandler::loadDummyMapping(
+            doc.documentElement(), "/fake/path");
+
+    ASSERT_EQ(pMapping->getSettings().size(), 1);
+    ASSERT_EQ(pMapping->getSettings().at(0)->variableName(), "myInteger1");
+    ASSERT_EQ(pMapping->getSettings().at(0)->value().toNumber(), 0);
+
+    dom.clear();
+    QTextStream(&dom)
+            << QString(kValidInteger).arg("20", "-100", "100", "50");
+    doc.setContent(
+            QString("<?xml version=\"1.0\" "
+                    "encoding=\"utf-8\"?><MixxxControllerPreset><settings>%1</"
+                    "settings></MixxxControllerPreset>")
+                    .arg(dom));
+
+    pMapping = LegacyDummyMappingFileHandler::loadDummyMapping(
+            doc.documentElement(), "/fake/path");
+
+    ASSERT_EQ(pMapping->getSettings().size(), 1);
+    ASSERT_EQ(pMapping->getSettings().at(0)->variableName(), "myInteger1");
+    ASSERT_EQ(pMapping->getSettings().at(0)->value().toNumber(), 20);
+}