uic: Fix some clang warnings

- Use range-based for
- Use isEmpty() instead .size(), streamline code
- Fix warnings about class definitions, use Q_DISABLE_COPY_MOVE
  and '= default' for trivial constructors

Change-Id: I76255fd9d80c3faffebda9a438e86e918c16d289
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/tools/uic/cpp/cppwriteinitialization.cpp

@@ -498,9 +498,7 @@ void WriteInitialization::acceptUI(DomUI *node)
              << language::startFunctionDefinition1("setupUi", parameterType, varName, m_option.indent);
 
     const QStringList connections = m_uic->databaseInfo()->connections();
-    for (int i=0; i<connections.size(); ++i) {
-        QString connection = connections.at(i);
-
+    for (const auto &connection : connections) {
         if (connection == QLatin1String("(default)"))
             continue;
 
@@ -900,8 +898,7 @@ void WriteInitialization::acceptLayout(DomLayout *node)
     if (m_layoutWidget) {
         bool left, top, right, bottom;
         left = top = right = bottom = false;
-        for (int i = 0; i < propList.size(); ++i) {
-            const DomProperty *p = propList.at(i);
+        for (const DomProperty *p : propList) {
             const QString propertyName = p->attributeName();
             if (propertyName == QLatin1String("leftMargin") && p->kind() == DomProperty::Number)
                 left = true;

src/tools/uic/cpp/cppwriteinitialization.h

@@ -161,7 +161,7 @@ private:
 // special initialization
 //
     class Item {
-        Q_DISABLE_COPY(Item)
+        Q_DISABLE_COPY_MOVE(Item)
     public:
         Item(const QString &itemClassName, const QString &indent, QTextStream &setupUiStream, QTextStream &retranslateUiStream, Driver *driver);
         ~Item();

src/tools/uic/databaseinfo.cpp

@@ -33,9 +33,7 @@
 
 QT_BEGIN_NAMESPACE
 
-DatabaseInfo::DatabaseInfo()
-{
-}
+DatabaseInfo::DatabaseInfo() = default;
 
 void DatabaseInfo::acceptUI(DomUI *node)
 {
@@ -59,10 +57,9 @@ void DatabaseInfo::acceptWidget(DomWidget *node)
     DomProperty *db = properties.value(QLatin1String("database"));
     if (db && db->elementStringList()) {
         QStringList info = db->elementStringList()->elementString();
-
-        QString connection = info.size() > 0 ? info.at(0) : QString();
-        if (connection.isEmpty())
+        if (info.isEmpty() || info.constFirst().isEmpty())
             return;
+        const QString &connection = info.constFirst();
         m_connections.append(connection);
 
         QString table = info.size() > 1 ? info.at(1) : QString();

src/tools/uic/treewalker.h

@@ -77,6 +77,9 @@ class DomButtonGroup;
 
 struct TreeWalker
 {
+    Q_DISABLE_COPY_MOVE(TreeWalker)
+
+    TreeWalker() = default;
     inline virtual ~TreeWalker() = default;
 
     virtual void acceptUI(DomUI *ui);