Minor performance improvements suggested by clang-tidy

 * Add const & to function parameters
 * Add const & to variables assigned from functions that return const &

Change-Id: Ibf35e54ffb78f164493222125411f2ba279cb861
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

4 files changed, 4 insertions, 4 deletions

diff --git a/src/quickcontrols2/qquickattachedobject.cpp b/src/quickcontrols2/qquickattachedobject.cpp
index c43f7dc5..722f22f9 100644
--- a/src/quickcontrols2/qquickattachedobject.cpp
+++ b/src/quickcontrols2/qquickattachedobject.cpp
@@ -119,7 +119,7 @@ static QList<QQuickAttachedObject *> findAttachedChildren(const QMetaObject *typ
         if (window) {
             item = window->contentItem();
 
-            const auto windowChildren = window->children();
+            const auto &windowChildren = window->children();
             for (QObject *child : windowChildren) {
                 QQuickWindow *childWindow = qobject_cast<QQuickWindow *>(child);
                 if (childWindow) {
diff --git a/src/quickcontrols2/qquickiconlabel.cpp b/src/quickcontrols2/qquickiconlabel.cpp
index b246621b..536b3c1b 100644
--- a/src/quickcontrols2/qquickiconlabel.cpp
+++ b/src/quickcontrols2/qquickiconlabel.cpp
@@ -408,7 +408,7 @@ QString QQuickIconLabel::text() const
     return d->text;
 }
 
-void QQuickIconLabel::setText(const QString text)
+void QQuickIconLabel::setText(const QString &text)
 {
     Q_D(QQuickIconLabel);
     if (d->text == text)
diff --git a/src/quickcontrols2/qquickiconlabel_p.h b/src/quickcontrols2/qquickiconlabel_p.h
index df79dbf2..75b77064 100644
--- a/src/quickcontrols2/qquickiconlabel_p.h
+++ b/src/quickcontrols2/qquickiconlabel_p.h
@@ -88,7 +88,7 @@ public:
     void setIcon(const QQuickIcon &icon);
 
     QString text() const;
-    void setText(const QString text);
+    void setText(const QString &text);
 
     QFont font() const;
     void setFont(const QFont &font);
diff --git a/src/quickcontrols2/qquickstyle.cpp b/src/quickcontrols2/qquickstyle.cpp
index e2b6678b..408a0de3 100644
--- a/src/quickcontrols2/qquickstyle.cpp
+++ b/src/quickcontrols2/qquickstyle.cpp
@@ -495,7 +495,7 @@ static bool qt_is_dark_system_theme()
 {
     if (const QPlatformTheme *theme = QGuiApplicationPrivate::platformTheme()) {
         if (const QPalette *systemPalette = theme->palette(QPlatformTheme::SystemPalette)) {
-            const QColor textColor = systemPalette->color(QPalette::WindowText);
+            const QColor &textColor = systemPalette->color(QPalette::WindowText);
             return textColor.red() > 128 && textColor.blue() > 128 && textColor.green() > 128;
         }
     }