use const_iterator

src/app/qgisapp.cpp

@@ -9128,7 +9128,7 @@ void QgisApp::onProjectCrsChanged()
   // handle datum transforms
   QList<QgsCoordinateReferenceSystem> transformsToAskFor = QList<QgsCoordinateReferenceSystem>();
   QMap<QString, QgsMapLayer *> layers = QgsProject::instance()->mapLayers();
-  for ( QMap<QString, QgsMapLayer *>::iterator it = layers.begin(); it != layers.end(); ++it )
+  for ( QMap<QString, QgsMapLayer *>::const_iterator it = layers.constBegin(); it != layers.constEnd(); ++it )
   {
     if ( !transformsToAskFor.contains( it.value()->crs() ) &&
          it.value()->crs() != QgsProject::instance()->crs() &&

src/app/qgisapp.h

@@ -1615,7 +1615,7 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
 
     void onFocusChanged( QWidget *oldWidget, QWidget *newWidget );
 
-    //! handles project crs changes
+    //! handle project crs changes
     void onProjectCrsChanged();
 
   signals: