qmllint/Quick: Warn about customizing native QtQuick.Controls styles

Certain properties in native QtQuick.Controls styles may not be
overridden. This patch adds a pass to the Quick qmllint plugin to warn
when a user modifies them.

The pass also uses the fact that these types (except Control) don't
inherit from each other to skip over checking for additional types
once a matching type is found.

Fixes: QTBUG-96737
Task-number: QTBUG-102277
Change-Id: I02f696aae716de45014736651385b6607eed6d15
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/plugins/qmllint/quick/quicklintplugin.cpp

@@ -49,9 +49,103 @@ void LayoutChildrenValidatorPass::run(const QQmlSA::Element &element)
                     element->sourceLocation());
 }
 
+ControlsNativeValidatorPass::ControlsNativeValidatorPass(QQmlSA::PassManager *manager)
+    : QQmlSA::ElementPass(manager)
+{
+    m_elements = {
+        ControlElement { "Control",
+                         QStringList { "background", "contentItem", "leftPadding", "rightPadding",
+                                       "topPadding", "bottomPadding", "horizontalPadding",
+                                       "verticalPadding", "padding" },
+                         false, true },
+        ControlElement { "Button", QStringList { "indicator" } },
+        ControlElement {
+                "ApplicationWindow",
+                QStringList { "background", "contentItem", "header", "footer", "menuBar" } },
+        ControlElement { "ComboBox", QStringList { "indicator" } },
+        ControlElement { "Dial", QStringList { "handle" } },
+        ControlElement { "Dialog", QStringList { "header", "footer" } },
+        ControlElement { "GroupBox", QStringList { "label" } },
+        ControlElement { "$internal$.QQuickIndicatorButton", QStringList { "indicator" }, false },
+        ControlElement { "Label", QStringList { "background" } },
+        ControlElement { "MenuItem", QStringList { "arrow" } },
+        ControlElement { "Page", QStringList { "header", "footer" } },
+        ControlElement { "Popup", QStringList { "background", "contentItem" } },
+        ControlElement { "RangeSlider", QStringList { "handle" } },
+        ControlElement { "Slider", QStringList { "handle" } },
+        ControlElement { "$internal$.QQuickSwipe",
+                         QStringList { "leftItem", "behindItem", "rightItem" }, false },
+        ControlElement { "TextArea", QStringList { "background" } },
+        ControlElement { "TextField", QStringList { "background" } },
+    };
+
+    for (const QString &module : { u"QtQuick.Controls.macOS"_qs, u"QtQuick.Controls.Windows"_qs }) {
+        if (!manager->hasImportedModule(module))
+            continue;
+
+        QQmlSA::Element control = resolveType(module, "Control");
+
+        for (ControlElement &element : m_elements) {
+            auto type = resolveType(element.isInModuleControls ? module : "QtQuick.Templates",
+                                    element.name);
+
+            if (type.isNull())
+                continue;
+
+            element.inheritsControl = !element.isControl && type->inherits(control);
+            element.element = type;
+        }
+
+        m_elements.removeIf([](const ControlElement &element) { return element.element.isNull(); });
+
+        break;
+    }
+}
+
+bool ControlsNativeValidatorPass::shouldRun(const QQmlSA::Element &element)
+{
+    for (const ControlElement &controlElement : m_elements) {
+        // If our element inherits control, we don't have to individually check for them here.
+        if (controlElement.inheritsControl)
+            continue;
+        if (element->inherits(controlElement.element))
+            return true;
+    }
+    return false;
+}
+
+void ControlsNativeValidatorPass::run(const QQmlSA::Element &element)
+{
+    for (const ControlElement &controlElement : m_elements) {
+        if (element->inherits(controlElement.element)) {
+            for (const QString &propertyName : controlElement.restrictedProperties) {
+                if (element->hasOwnPropertyBindings(propertyName)) {
+                    emitWarning(QStringLiteral("Not allowed to override \"%1\" because native "
+                                               "styles cannot be customized: See "
+                                               "https://doc-snapshots.qt.io/qt6-dev/"
+                                               "qtquickcontrols2-customize.html#customization-"
+                                               "reference for more information.")
+                                        .arg(propertyName),
+                                element->sourceLocation());
+                }
+            }
+            // Since all the different types we have rules for don't inherit from each other (except
+            // for Control) we don't have to keep checking whether other types match once we've
+            // found one that has been inherited from.
+            if (!controlElement.isControl)
+                break;
+        }
+    }
+}
+
 void QmlLintQuickPlugin::registerPasses(QQmlSA::PassManager *manager,
                                         const QQmlSA::Element &rootElement)
 {
     Q_UNUSED(rootElement);
-    manager->registerElementPass(std::make_unique<LayoutChildrenValidatorPass>(manager));
+    if (manager->hasImportedModule(u"QtQuick.Layouts"_qs))
+        manager->registerElementPass(std::make_unique<LayoutChildrenValidatorPass>(manager));
+
+    if (manager->hasImportedModule(u"QtQuick.Controls.macOS"_qs)
+        || manager->hasImportedModule(u"QtQuick.Controls.Windows"_qs))
+        manager->registerElementPass(std::make_unique<ControlsNativeValidatorPass>(manager));
 }

src/plugins/qmllint/quick/quicklintplugin.h

@@ -29,7 +29,9 @@
 #ifndef QUICKLINTPLUGIN_H
 #define QUICKLINTPLUGIN_H
 
-#include <QtPlugin>
+#include <QtCore/qplugin.h>
+#include <QtCore/qlist.h>
+
 #include <QtQmlCompiler/private/qqmlsa_p.h>
 
 class QmlLintQuickPlugin : public QObject, public QQmlSA::LintPlugin
@@ -54,4 +56,26 @@ private:
     QQmlSA::Element m_layout;
 };
 
+class ControlsNativeValidatorPass : public QQmlSA::ElementPass
+{
+public:
+    ControlsNativeValidatorPass(QQmlSA::PassManager *manager);
+
+    bool shouldRun(const QQmlSA::Element &element) override;
+    void run(const QQmlSA::Element &element) override;
+
+private:
+    struct ControlElement
+    {
+        QString name;
+        QStringList restrictedProperties;
+        bool isInModuleControls = true;
+        bool isControl = false;
+        bool inheritsControl = false;
+        QQmlSA::Element element = {};
+    };
+
+    QList<ControlElement> m_elements;
+};
+
 #endif // QUICKLINTPLUGIN_H