diff --git a/src/app/composer/qgscomposerlegendwidget.cpp b/src/app/composer/qgscomposerlegendwidget.cpp
index de62a7e7487..0f61208dc69 100644
--- a/src/app/composer/qgscomposerlegendwidget.cpp
+++ b/src/app/composer/qgscomposerlegendwidget.cpp
@@ -795,7 +795,7 @@ void QgsComposerLegendWidget::resetLayerNodeToDefaults()
 
   mLegend->beginCommand( tr( "Legend updated" ) );
 
-  foreach ( QString key, nodeLayer->customProperties() )
+  foreach ( const QString& key, nodeLayer->customProperties() )
   {
     if ( key.startsWith( "legend/" ) )
       nodeLayer->removeCustomProperty( key );
diff --git a/src/app/composer/qgscomposermapwidget.cpp b/src/app/composer/qgscomposermapwidget.cpp
index e936ba5fa82..8e0d2703104 100644
--- a/src/app/composer/qgscomposermapwidget.cpp
+++ b/src/app/composer/qgscomposermapwidget.cpp
@@ -298,7 +298,7 @@ void QgsComposerMapWidget::aboutToShowVisibilityPresetsMenu()
     return;
 
   menu->clear();
-  foreach ( QString presetName, QgsProject::instance()->visibilityPresetCollection()->presets() )
+  foreach ( const QString& presetName, QgsProject::instance()->visibilityPresetCollection()->presets() )
   {
     QAction* a = menu->addAction( presetName, this, SLOT( visibilityPresetSelected() ) );
     a->setCheckable( true );
diff --git a/src/app/main.cpp b/src/app/main.cpp
index 1e6cfb6de07..c0d5d141e54 100644
--- a/src/app/main.cpp
+++ b/src/app/main.cpp
@@ -1141,7 +1141,7 @@ APP_EXPORT int main( int argc, char *argv[] )
     QList< QPair<QgsVectorLayer *, int > > layers;
     if ( !dxfPreset.isEmpty() )
     {
-      foreach ( QString layer, QgsProject::instance()->visibilityPresetCollection()->presetVisibleLayers( dxfPreset ) )
+      foreach ( const QString& layer, QgsProject::instance()->visibilityPresetCollection()->presetVisibleLayers( dxfPreset ) )
       {
         QgsVectorLayer *vl = qobject_cast<QgsVectorLayer *>( QgsMapLayerRegistry::instance()->mapLayer( layer ) );
         if ( !vl )
diff --git a/src/app/qgisapp.cpp b/src/app/qgisapp.cpp
index 231aad83cf2..21369afb2a5 100644
--- a/src/app/qgisapp.cpp
+++ b/src/app/qgisapp.cpp
@@ -2870,7 +2870,7 @@ void QgisApp::updateProjectFromTemplates()
   mProjectFromTemplateMenu->clear();
 
   // Add entries
-  foreach ( QString templateFile, templateFiles )
+  foreach ( const QString& templateFile, templateFiles )
   {
     mProjectFromTemplateMenu->addAction( templateFile );
   }
@@ -3003,7 +3003,7 @@ QString QgisApp::crsAndFormatAdjustedLayerUri( const QString &uri, const QString
 
   // Adjust layer CRS to project CRS
   QgsCoordinateReferenceSystem testCrs;
-  foreach ( QString c, supportedCrs )
+  foreach ( const QString& c, supportedCrs )
   {
     testCrs.createFromOgcWmsCrs( c );
     if ( testCrs == mMapCanvas->mapSettings().destinationCrs() )
@@ -3016,7 +3016,7 @@ QString QgisApp::crsAndFormatAdjustedLayerUri( const QString &uri, const QString
 
   // Use the last used image format
   QString lastImageEncoding = QSettings().value( "/qgis/lastWmsImageEncoding", "image/png" ).toString();
-  foreach ( QString fmt, supportedFormats )
+  foreach ( const QString& fmt, supportedFormats )
   {
     if ( fmt == lastImageEncoding )
     {
@@ -3561,7 +3561,7 @@ void QgisApp::addDatabaseLayers( QStringList const & layerPathList, QString cons
 
   QApplication::setOverrideCursor( Qt::WaitCursor );
 
-  foreach ( QString layerPath, layerPathList )
+  foreach ( const QString& layerPath, layerPathList )
   {
     // create the layer
     QgsDataSourceURI uri( layerPath );
diff --git a/src/app/qgsbookmarks.cpp b/src/app/qgsbookmarks.cpp
index a55aa3f7b6c..84e059d0c0c 100644
--- a/src/app/qgsbookmarks.cpp
+++ b/src/app/qgsbookmarks.cpp
@@ -293,7 +293,7 @@ void QgsBookmarks::importFromXML()
   QStringList queriesList = queries.split( ";" );
   QSqlQuery query( model->database() );
 
-  foreach ( QString queryTxt, queriesList )
+  foreach ( const QString& queryTxt, queriesList )
   {
     if ( queryTxt.trimmed().isEmpty() )
     {
diff --git a/src/app/qgsbrowserdockwidget.cpp b/src/app/qgsbrowserdockwidget.cpp
index 202b73bd37e..37da56792cf 100644
--- a/src/app/qgsbrowserdockwidget.cpp
+++ b/src/app/qgsbrowserdockwidget.cpp
@@ -135,7 +135,7 @@ class QgsBrowserTreeFilterProxyModel : public QSortFilterProxyModel
       mREList.clear();
       if ( mPatternSyntax == "normal" )
       {
-        foreach ( QString f, mFilter.split( "|" ) )
+        foreach ( const QString& f, mFilter.split( "|" ) )
         {
           QRegExp rx( QString( "*%1*" ).arg( f.trimmed() ) );
           rx.setPatternSyntax( QRegExp::Wildcard );
@@ -145,7 +145,7 @@ class QgsBrowserTreeFilterProxyModel : public QSortFilterProxyModel
       }
       else if ( mPatternSyntax == "wildcard" )
       {
-        foreach ( QString f, mFilter.split( "|" ) )
+        foreach ( const QString& f, mFilter.split( "|" ) )
         {
           QRegExp rx( f.trimmed() );
           rx.setPatternSyntax( QRegExp::Wildcard );
@@ -175,7 +175,7 @@ class QgsBrowserTreeFilterProxyModel : public QSortFilterProxyModel
     {
       if ( mPatternSyntax == "normal" || mPatternSyntax == "wildcard" )
       {
-        foreach ( QRegExp rx, mREList )
+        foreach ( const QRegExp& rx, mREList )
         {
           QgsDebugMsg( QString( "value: [%1] rx: [%2] match: %3" ).arg( value ).arg( rx.pattern() ).arg( rx.exactMatch( value ) ) );
           if ( rx.exactMatch( value ) )
@@ -184,7 +184,7 @@ class QgsBrowserTreeFilterProxyModel : public QSortFilterProxyModel
       }
       else
       {
-        foreach ( QRegExp rx, mREList )
+        foreach ( const QRegExp& rx, mREList )
         {
           QgsDebugMsg( QString( "value: [%1] rx: [%2] match: %3" ).arg( value ).arg( rx.pattern() ).arg( rx.indexIn( value ) ) );
           if ( rx.indexIn( value ) != -1 )
diff --git a/src/app/qgsclipboard.cpp b/src/app/qgsclipboard.cpp
index f0d16f0aa03..f59faefd571 100644
--- a/src/app/qgsclipboard.cpp
+++ b/src/app/qgsclipboard.cpp
@@ -162,7 +162,7 @@ QgsFeatureList QgsClipboard::copyOf( const QgsFields &fields )
     return mFeatureClipboard;
 
   QgsFeatureList features;
-  foreach ( QString row, values )
+  foreach ( const QString& row, values )
   {
     // Assume that it's just WKT for now.
     QgsGeometry* geometry = QgsGeometry::fromWkt( row );
diff --git a/src/app/qgsmaptoolfeatureaction.cpp b/src/app/qgsmaptoolfeatureaction.cpp
index dfef6408561..baf0cab9555 100644
--- a/src/app/qgsmaptoolfeatureaction.cpp
+++ b/src/app/qgsmaptoolfeatureaction.cpp
@@ -131,7 +131,7 @@ bool QgsMapToolFeatureAction::doAction( QgsVectorLayer *layer, int x, int y )
   if ( featList.size() == 0 )
     return false;
 
-  foreach ( QgsFeature feat, featList )
+  foreach ( const QgsFeature& feat, featList )
   {
     if ( layer->actions()->defaultAction() >= 0 )
     {
diff --git a/src/app/qgsoptions.cpp b/src/app/qgsoptions.cpp
index 9ecfe7b24c3..340e29d2671 100644
--- a/src/app/qgsoptions.cpp
+++ b/src/app/qgsoptions.cpp
@@ -750,7 +750,7 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WindowFlags fl ) :
   lblSystemLocale->setText( tr( "Detected active locale on your system: %1" ).arg( mySystemLocale ) );
   QString myUserLocale = settings.value( "locale/userLocale", "" ).toString();
   QStringList myI18nList = i18nList();
-  foreach ( QString l, myI18nList )
+  foreach ( const QString& l, myI18nList )
   {
     cboLocale->addItem( QIcon( QString( ":/images/flags/%1.png" ).arg( l ) ), QLocale( l ).nativeLanguageName(), l );
   }
@@ -1762,11 +1762,11 @@ void QgsOptions::loadGdalDriverList()
   // myDrivers.sort();
   // sort list case insensitive - no existing function for this!
   QMap<QString, QString> strMap;
-  foreach ( QString str, myDrivers )
+  foreach ( const QString& str, myDrivers )
     strMap.insert( str.toLower(), str );
   myDrivers = strMap.values();
 
-  foreach ( QString myName, myDrivers )
+  foreach ( const QString& myName, myDrivers )
   {
     QTreeWidgetItem * mypItem = new QTreeWidgetItem( QStringList( myName ) );
     if ( mySkippedDrivers.contains( myName ) )
@@ -1794,13 +1794,13 @@ void QgsOptions::loadGdalDriverList()
 
   // populate cmbEditCreateOptions with gdal write drivers - sorted, GTiff first
   strMap.clear();
-  foreach ( QString str, myGdalWriteDrivers )
+  foreach ( const QString& str, myGdalWriteDrivers )
     strMap.insert( str.toLower(), str );
   myGdalWriteDrivers = strMap.values();
   myGdalWriteDrivers.removeAll( "Gtiff" );
   myGdalWriteDrivers.prepend( "GTiff" );
   cmbEditCreateOptions->clear();
-  foreach ( QString myName, myGdalWriteDrivers )
+  foreach ( const QString& myName, myGdalWriteDrivers )
   {
     cmbEditCreateOptions->addItem( myName );
   }
diff --git a/src/app/qgspluginregistry.cpp b/src/app/qgspluginregistry.cpp
index 96409696bb2..714b57de274 100644
--- a/src/app/qgspluginregistry.cpp
+++ b/src/app/qgspluginregistry.cpp
@@ -138,8 +138,9 @@ void QgsPluginRegistry::dump()
   if ( mPythonUtils && mPythonUtils->isEnabled() )
   {
     QgsDebugMsg( "PYTHON PLUGINS IN REGISTRY:" );
-    foreach ( QString pluginName, mPythonUtils->listActivePlugins() )
+    foreach ( const QString& pluginName, mPythonUtils->listActivePlugins() )
     {
+      Q_UNUSED( pluginName );
       QgsDebugMsg( pluginName );
     }
   }
@@ -176,7 +177,7 @@ void QgsPluginRegistry::unloadAll()
 
   if ( mPythonUtils && mPythonUtils->isEnabled() )
   {
-    foreach ( QString pluginName, mPythonUtils->listActivePlugins() )
+    foreach ( const QString& pluginName, mPythonUtils->listActivePlugins() )
     {
       mPythonUtils->unloadPlugin( pluginName );
     }
diff --git a/src/app/qgsprojectlayergroupdialog.cpp b/src/app/qgsprojectlayergroupdialog.cpp
index ca0efbda9e1..8a7f7a05524 100644
--- a/src/app/qgsprojectlayergroupdialog.cpp
+++ b/src/app/qgsprojectlayergroupdialog.cpp
@@ -62,7 +62,7 @@ QStringList QgsProjectLayerGroupDialog::selectedGroups() const
 {
   QStringList groups;
   QgsLayerTreeModel* model = mTreeView->layerTreeModel();
-  foreach ( QModelIndex index, mTreeView->selectionModel()->selectedIndexes() )
+  foreach ( const QModelIndex& index, mTreeView->selectionModel()->selectedIndexes() )
   {
     QgsLayerTreeNode* node = model->index2node( index );
     if ( QgsLayerTree::isGroup( node ) )
@@ -75,7 +75,7 @@ QStringList QgsProjectLayerGroupDialog::selectedLayerIds() const
 {
   QStringList layerIds;
   QgsLayerTreeModel* model = mTreeView->layerTreeModel();
-  foreach ( QModelIndex index, mTreeView->selectionModel()->selectedIndexes() )
+  foreach ( const QModelIndex& index, mTreeView->selectionModel()->selectedIndexes() )
   {
     QgsLayerTreeNode* node = model->index2node( index );
     if ( QgsLayerTree::isLayer( node ) )
@@ -88,7 +88,7 @@ QStringList QgsProjectLayerGroupDialog::selectedLayerNames() const
 {
   QStringList layerNames;
   QgsLayerTreeModel* model = mTreeView->layerTreeModel();
-  foreach ( QModelIndex index, mTreeView->selectionModel()->selectedIndexes() )
+  foreach ( const QModelIndex& index, mTreeView->selectionModel()->selectedIndexes() )
   {
     QgsLayerTreeNode* node = model->index2node( index );
     if ( QgsLayerTree::isLayer( node ) )
@@ -204,7 +204,7 @@ void QgsProjectLayerGroupDialog::removeEmbeddedNodes( QgsLayerTreeGroup* node )
 
 void QgsProjectLayerGroupDialog::onTreeViewSelectionChanged()
 {
-  foreach ( QModelIndex index, mTreeView->selectionModel()->selectedIndexes() )
+  foreach ( const QModelIndex& index, mTreeView->selectionModel()->selectedIndexes() )
   {
     unselectChildren( index );
   }
diff --git a/src/app/qgsprojectproperties.cpp b/src/app/qgsprojectproperties.cpp
index ea2398cdbd4..fcf5f2f0a2e 100644
--- a/src/app/qgsprojectproperties.cpp
+++ b/src/app/qgsprojectproperties.cpp
@@ -311,7 +311,7 @@ QgsProjectProperties::QgsProjectProperties( QgsMapCanvas* mapCanvas, QWidget *pa
     if ( grpWMSList->isChecked() )
     {
       QStringList list;
-      foreach ( QString value, values )
+      foreach ( const QString& value, values )
       {
         list << QString( "EPSG:%1" ).arg( value );
       }
diff --git a/src/app/qgsrasterlayerproperties.cpp b/src/app/qgsrasterlayerproperties.cpp
index 3b3e409b0c6..7f25df6eee9 100644
--- a/src/app/qgsrasterlayerproperties.cpp
+++ b/src/app/qgsrasterlayerproperties.cpp
@@ -355,7 +355,7 @@ QgsRasterLayerProperties::QgsRasterLayerProperties( QgsMapLayer* lyr, QgsMapCanv
 
   //fill available renderers into combo box
   QgsRasterRendererRegistryEntry entry;
-  foreach ( QString name, QgsRasterRendererRegistry::instance()->renderersList() )
+  foreach ( const QString& name, QgsRasterRendererRegistry::instance()->renderersList() )
   {
     if ( QgsRasterRendererRegistry::instance()->rendererData( name, entry ) )
     {
diff --git a/src/app/qgssnappingdialog.cpp b/src/app/qgssnappingdialog.cpp
index 7475eeb5d0f..cbb5c91b887 100644
--- a/src/app/qgssnappingdialog.cpp
+++ b/src/app/qgssnappingdialog.cpp
@@ -459,7 +459,7 @@ void QgsSnappingDialog::addLayer( QgsMapLayer *theMapLayer )
 
 void QgsSnappingDialog::layersWillBeRemoved( QStringList thelayers )
 {
-  foreach ( QString theLayerId, thelayers )
+  foreach ( const QString& theLayerId, thelayers )
   {
     QTreeWidgetItem *item = 0;
 
diff --git a/src/app/qgsvisibilitypresets.cpp b/src/app/qgsvisibilitypresets.cpp
index 16d1130eb80..bd1d395882b 100644
--- a/src/app/qgsvisibilitypresets.cpp
+++ b/src/app/qgsvisibilitypresets.cpp
@@ -59,7 +59,7 @@ void QgsVisibilityPresets::addPerLayerCheckedLegendSymbols( QgsVisibilityPresetC
 {
   QgsLayerTreeModel* model = QgisApp::instance()->layerTreeView()->layerTreeModel();
 
-  foreach ( QString layerID, rec.mVisibleLayerIDs )
+  foreach ( const QString& layerID, rec.mVisibleLayerIDs )
   {
     QgsLayerTreeLayer* nodeLayer = model->rootGroup()->findLayer( layerID );
     if ( !nodeLayer )
@@ -90,7 +90,7 @@ void QgsVisibilityPresets::addPerLayerCurrentStyle( QgsVisibilityPresetCollectio
 {
   QgsLayerTreeModel* model = QgisApp::instance()->layerTreeView()->layerTreeModel();
 
-  foreach ( QString layerID, rec.mVisibleLayerIDs )
+  foreach ( const QString& layerID, rec.mVisibleLayerIDs )
   {
     QgsLayerTreeLayer* nodeLayer = model->rootGroup()->findLayer( layerID );
     if ( !nodeLayer )
@@ -136,7 +136,7 @@ QStringList QgsVisibilityPresets::orderedPresetVisibleLayers( const QString& nam
   QgsLayerTreeMapCanvasBridge* bridge = QgisApp::instance()->layerTreeCanvasBridge();
   QStringList order = bridge->hasCustomLayerOrder() ? bridge->customLayerOrder() : bridge->defaultLayerOrder();
   QStringList order2;
-  foreach ( QString layerID, order )
+  foreach ( const QString& layerID, order )
   {
     if ( visibleIds.contains( layerID ) )
       order2 << layerID;
diff --git a/src/core/composer/qgsatlascomposition.cpp b/src/core/composer/qgsatlascomposition.cpp
index fd13ec21e6c..d582ab2b33d 100644
--- a/src/core/composer/qgsatlascomposition.cpp
+++ b/src/core/composer/qgsatlascomposition.cpp
@@ -70,7 +70,7 @@ void QgsAtlasComposition::removeLayers( QStringList layers )
     return;
   }
 
-  foreach ( QString layerId, layers )
+  foreach ( const QString& layerId, layers )
   {
     if ( layerId == mCoverageLayer->id() )
     {
diff --git a/src/core/composer/qgscomposermap.cpp b/src/core/composer/qgscomposermap.cpp
index 523d53971cf..9f8c5547cfc 100644
--- a/src/core/composer/qgscomposermap.cpp
+++ b/src/core/composer/qgscomposermap.cpp
@@ -555,7 +555,7 @@ QStringList QgsComposerMap::layersToRender() const
 
     QStringList layerNames = exprVal.toString().split( "|" );
     //need to convert layer names to layer ids
-    Q_FOREACH ( QString name, layerNames )
+    Q_FOREACH ( const QString& name, layerNames )
     {
       QList< QgsMapLayer* > matchingLayers = QgsMapLayerRegistry::instance()->mapLayersByName( name );
       Q_FOREACH ( QgsMapLayer* layer, matchingLayers )
diff --git a/src/core/composer/qgscomposertablev2.cpp b/src/core/composer/qgscomposertablev2.cpp
index fc863123db0..5288e26a81f 100644
--- a/src/core/composer/qgscomposertablev2.cpp
+++ b/src/core/composer/qgscomposertablev2.cpp
@@ -942,7 +942,7 @@ bool QgsComposerTableV2::calculateMaxColumnWidths()
         //column width set to automatic, so check content size
         QStringList multiLineSplit = ( *colIt ).toString().split( "\n" );
         currentCellTextWidth = 0;
-        Q_FOREACH ( QString line, multiLineSplit )
+        Q_FOREACH ( const QString& line, multiLineSplit )
         {
           currentCellTextWidth = qMax( currentCellTextWidth, QgsComposerUtils::textWidthMM( mContentFont, line ) );
         }
@@ -1168,7 +1168,7 @@ bool QgsComposerTableV2::textRequiresWrapping( const QString& text, double colum
 
   QStringList multiLineSplit = text.split( "\n" );
   double currentTextWidth = 0;
-  Q_FOREACH ( QString line, multiLineSplit )
+  Q_FOREACH ( const QString& line, multiLineSplit )
   {
     currentTextWidth = qMax( currentTextWidth, QgsComposerUtils::textWidthMM( font, line ) );
   }
@@ -1180,7 +1180,7 @@ QString QgsComposerTableV2::wrappedText( const QString &value, double columnWidt
 {
   QStringList lines = value.split( "\n" );
   QStringList outLines;
-  Q_FOREACH ( QString line, lines )
+  Q_FOREACH ( const QString& line, lines )
   {
     if ( textRequiresWrapping( line, columnWidth, font ) )
     {
@@ -1188,7 +1188,7 @@ QString QgsComposerTableV2::wrappedText( const QString &value, double columnWidt
       QStringList words = line.split( " " );
       QStringList linesToProcess;
       QString wordsInCurrentLine;
-      Q_FOREACH ( QString word, words )
+      Q_FOREACH ( const QString& word, words )
       {
         if ( textRequiresWrapping( word, columnWidth, font ) )
         {
@@ -1208,7 +1208,7 @@ QString QgsComposerTableV2::wrappedText( const QString &value, double columnWidt
       if ( !wordsInCurrentLine.isEmpty() )
         linesToProcess << wordsInCurrentLine;
 
-      Q_FOREACH ( QString line, linesToProcess )
+      Q_FOREACH ( const QString& line, linesToProcess )
       {
         QString remainingText = line;
         int lastPos = remainingText.lastIndexOf( " " );
diff --git a/src/core/diagram/qgshistogramdiagram.cpp b/src/core/diagram/qgshistogramdiagram.cpp
index cde130f1dca..5bd32bc87d9 100644
--- a/src/core/diagram/qgshistogramdiagram.cpp
+++ b/src/core/diagram/qgshistogramdiagram.cpp
@@ -53,7 +53,7 @@ QSizeF QgsHistogramDiagram::diagramSize( const QgsFeature& feature, const QgsRen
   if ( feature.fields() )
     expressionContext.setFields( *feature.fields() );
 
-  foreach ( QString cat, s.categoryAttributes )
+  foreach ( const QString& cat, s.categoryAttributes )
   {
     QgsExpression* expression = getExpression( cat, expressionContext );
     maxValue = qMax( expression->evaluate( &expressionContext ).toDouble(), maxValue );
@@ -135,7 +135,7 @@ void QgsHistogramDiagram::renderDiagram( const QgsFeature& feature, QgsRenderCon
   if ( feature.fields() )
     expressionContext.setFields( *feature.fields() );
 
-  foreach ( QString cat, s.categoryAttributes )
+  foreach ( const QString& cat, s.categoryAttributes )
   {
     QgsExpression* expression = getExpression( cat, expressionContext );
     double currentVal = expression->evaluate( &expressionContext ).toDouble();
diff --git a/src/core/dxf/qgsdxfexport.cpp b/src/core/dxf/qgsdxfexport.cpp
index 4199d58a5b8..37dd41e7e88 100644
--- a/src/core/dxf/qgsdxfexport.cpp
+++ b/src/core/dxf/qgsdxfexport.cpp
@@ -588,7 +588,7 @@ void QgsDxfExport::writeTables()
   writeGroup( 100, "AcDbSymbolTable" );
   writeGroup( 70, 0 );
 
-  foreach ( QString block, QStringList() << "*Model_Space" << "*Paper_Space" << "*Paper_Space0" )
+  foreach ( const QString& block, QStringList() << "*Model_Space" << "*Paper_Space" << "*Paper_Space0" )
   {
     writeGroup( 0, "BLOCK_RECORD" );
     mBlockHandles.insert( block, writeHandle() );
@@ -722,7 +722,7 @@ void QgsDxfExport::writeTables()
       {
         QList<QVariant> values;
         layerIt->first->uniqueValues( layerIt->second, values );
-        foreach ( QVariant v, values )
+        foreach ( const QVariant& v, values )
         {
           layerNames << dxfLayerName( v.toString() );
         }
@@ -748,7 +748,7 @@ void QgsDxfExport::writeTables()
   writeGroup( 6, "CONTINUOUS" );
   writeHandle( 390, DXF_HANDPLOTSTYLE );
 
-  foreach ( QString layerName, layerNames )
+  foreach ( const QString& layerName, layerNames )
   {
     writeGroup( 0, "LAYER" );
     writeHandle();
@@ -794,7 +794,7 @@ void QgsDxfExport::writeBlocks()
   startSection();
   writeGroup( 2, "BLOCKS" );
 
-  foreach ( QString block, QStringList() << "*Model_Space" << "*Paper_Space" << "*Paper_Space0" )
+  foreach ( const QString& block, QStringList() << "*Model_Space" << "*Paper_Space" << "*Paper_Space0" )
   {
     writeGroup( 0, "BLOCK" );
     writeHandle();
@@ -3869,7 +3869,7 @@ QList< QPair< QgsSymbolLayerV2*, QgsSymbolV2* > > QgsDxfExport::symbolLayers( Qg
 void QgsDxfExport::writeDefaultLinetypes()
 {
   // continuous (Qt solid line)
-  foreach ( QString ltype, QStringList() << "ByLayer" << "ByBlock" << "CONTINUOUS" )
+  foreach ( const QString& ltype, QStringList() << "ByLayer" << "ByBlock" << "CONTINUOUS" )
   {
     writeGroup( 0, "LTYPE" );
     writeHandle();
diff --git a/src/core/effects/qgspainteffectregistry.cpp b/src/core/effects/qgspainteffectregistry.cpp
index c24fc3e5fcc..90c6789eab9 100644
--- a/src/core/effects/qgspainteffectregistry.cpp
+++ b/src/core/effects/qgspainteffectregistry.cpp
@@ -53,7 +53,7 @@ QgsPaintEffectRegistry::QgsPaintEffectRegistry()
 
 QgsPaintEffectRegistry::~QgsPaintEffectRegistry()
 {
-  foreach ( QString name, mMetadata.keys() )
+  foreach ( const QString& name, mMetadata.keys() )
   {
     delete mMetadata[name];
   }
diff --git a/src/core/gps/qgsgpsdetector.cpp b/src/core/gps/qgsgpsdetector.cpp
index 9d56b1a56cf..aa541b578b9 100644
--- a/src/core/gps/qgsgpsdetector.cpp
+++ b/src/core/gps/qgsgpsdetector.cpp
@@ -44,7 +44,7 @@ QList< QPair<QString, QString> > QgsGPSDetector::availablePorts()
 
 #ifdef Q_OS_LINUX
   // look for linux serial devices
-  foreach ( QString linuxDev, QStringList() << "/dev/ttyS%1" << "/dev/ttyUSB%1" << "/dev/rfcomm%1" << "/dev/ttyACM%1" )
+  foreach ( const QString& linuxDev, QStringList() << "/dev/ttyS%1" << "/dev/ttyUSB%1" << "/dev/rfcomm%1" << "/dev/ttyACM%1" )
   {
     for ( int i = 0; i < 10; ++i )
     {
@@ -58,7 +58,7 @@ QList< QPair<QString, QString> > QgsGPSDetector::availablePorts()
 
 #ifdef Q_OS_FREEBSD
   // and freebsd devices (untested)
-  foreach ( QString freebsdDev, QStringList() << "/dev/cuaa%1" << "/dev/ucom%1" )
+  foreach ( const QString& freebsdDev, QStringList() << "/dev/cuaa%1" << "/dev/ucom%1" )
   {
     for ( int i = 0; i < 10; ++i )
     {
diff --git a/src/core/layertree/qgslayertreemodel.cpp b/src/core/layertree/qgslayertreemodel.cpp
index 3016944313c..bd56b29891a 100644
--- a/src/core/layertree/qgslayertreemodel.cpp
+++ b/src/core/layertree/qgslayertreemodel.cpp
@@ -415,7 +415,7 @@ static bool _isChildOfNodes( QgsLayerTreeNode* child, QList<QgsLayerTreeNode*> n
 QList<QgsLayerTreeNode*> QgsLayerTreeModel::indexes2nodes( const QModelIndexList& list, bool skipInternal ) const
 {
   QList<QgsLayerTreeNode*> nodes;
-  foreach ( QModelIndex index, list )
+  foreach ( const QModelIndex& index, list )
   {
     QgsLayerTreeNode* node = index2node( index );
     if ( !node )
diff --git a/src/core/layertree/qgslayertreeregistrybridge.cpp b/src/core/layertree/qgslayertreeregistrybridge.cpp
index b22042f3e5f..69e24dd6963 100644
--- a/src/core/layertree/qgslayertreeregistrybridge.cpp
+++ b/src/core/layertree/qgslayertreeregistrybridge.cpp
@@ -84,7 +84,7 @@ void QgsLayerTreeRegistryBridge::layersWillBeRemoved( QStringList layerIds )
   // the registry _again_ in groupRemovedChildren() - this prevents it
   mRegistryRemovingLayers = true;
 
-  foreach ( QString layerId, layerIds )
+  foreach ( const QString& layerId, layerIds )
   {
     QgsLayerTreeLayer* nodeLayer = mRoot->findLayer( layerId );
     if ( nodeLayer )
@@ -132,7 +132,7 @@ void QgsLayerTreeRegistryBridge::groupRemovedChildren()
   // remove only those that really do not exist in the tree
   // (ignores layers that were dragged'n'dropped: 1. drop new 2. remove old)
   QStringList toRemove;
-  foreach ( QString layerId, mLayerIdsForRemoval )
+  foreach ( const QString& layerId, mLayerIdsForRemoval )
     if ( !mRoot->findLayer( layerId ) )
       toRemove << layerId;
   mLayerIdsForRemoval.clear();
diff --git a/src/core/layertree/qgslayertreeutils.cpp b/src/core/layertree/qgslayertreeutils.cpp
index cabd70bda12..51efeac8be9 100644
--- a/src/core/layertree/qgslayertreeutils.cpp
+++ b/src/core/layertree/qgslayertreeutils.cpp
@@ -95,7 +95,7 @@ bool QgsLayerTreeUtils::readOldLegendLayerOrder( const QDomElement& legendElem,
   if ( !res && hasCustomOrder )
     return false; // invalid state
 
-  foreach ( QString layerId, layerIndexes )
+  foreach ( const QString& layerId, layerIndexes )
   {
     QgsDebugMsg( layerId );
     order.append( layerId );
diff --git a/src/core/pal/layer.cpp b/src/core/pal/layer.cpp
index 5f21fc191ea..9ed336601dd 100644
--- a/src/core/pal/layer.cpp
+++ b/src/core/pal/layer.cpp
@@ -312,7 +312,7 @@ namespace pal
   void Layer::joinConnectedFeatures()
   {
     // go through all label texts
-    Q_FOREACH ( QString labelText, mConnectedTexts )
+    Q_FOREACH ( const QString& labelText, mConnectedTexts )
     {
       if ( !mConnectedHashtable.contains( labelText ) )
         continue; // shouldn't happen
diff --git a/src/core/pal/pal.cpp b/src/core/pal/pal.cpp
index 23a3cc0e8de..754d46b5657 100644
--- a/src/core/pal/pal.cpp
+++ b/src/core/pal/pal.cpp
@@ -313,7 +313,7 @@ namespace pal
     QStringList layersWithFeaturesInBBox;
 
     mMutex.lock();
-    Q_FOREACH ( QString layerName, layerNames )
+    Q_FOREACH ( const QString& layerName, layerNames )
     {
       layer = mLayers.value( layerName, 0 );
       if ( !layer )
diff --git a/src/core/qgsapplication.cpp b/src/core/qgsapplication.cpp
index 8704c455a11..709bda3fc5a 100644
--- a/src/core/qgsapplication.cpp
+++ b/src/core/qgsapplication.cpp
@@ -1025,14 +1025,14 @@ void QgsApplication::copyPath( QString src, QString dst )
   if ( ! dir.exists() )
     return;
 
-  foreach ( QString d, dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot ) )
+  foreach ( const QString& d, dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot ) )
   {
     QString dst_path = dst + QDir::separator() + d;
     dir.mkpath( dst_path );
     copyPath( src + QDir::separator() + d, dst_path );
   }
 
-  foreach ( QString f, dir.entryList( QDir::Files ) )
+  foreach ( const QString& f, dir.entryList( QDir::Files ) )
   {
     QFile::copy( src + QDir::separator() + f, dst + QDir::separator() + f );
   }
diff --git a/src/core/qgsbrowsermodel.cpp b/src/core/qgsbrowsermodel.cpp
index 3fa9ed7f41c..c6ac28be179 100644
--- a/src/core/qgsbrowsermodel.cpp
+++ b/src/core/qgsbrowsermodel.cpp
@@ -109,7 +109,7 @@ void QgsBrowserModel::addRootItems()
   }
 
   // add drives
-  foreach ( QFileInfo drive, QDir::drives() )
+  foreach ( const QFileInfo& drive, QDir::drives() )
   {
     QString path = drive.absolutePath();
     QgsDirectoryItem *item = new QgsDirectoryItem( NULL, path, path );
diff --git a/src/core/qgscolorscheme.cpp b/src/core/qgscolorscheme.cpp
index 64cc7f03d30..02a37e88922 100644
--- a/src/core/qgscolorscheme.cpp
+++ b/src/core/qgscolorscheme.cpp
@@ -69,7 +69,7 @@ QgsNamedColorList QgsRecentColorScheme::fetchColors( const QString &context, con
 
   //generate list from recent colors
   QgsNamedColorList colorList;
-  foreach ( QVariant color, recentColorVariants )
+  foreach ( const QVariant& color, recentColorVariants )
   {
     colorList.append( qMakePair( color.value<QColor>(), QgsSymbolLayerV2Utils::colorToName( color.value<QColor>() ) ) );
   }
diff --git a/src/core/qgsconditionalstyle.cpp b/src/core/qgsconditionalstyle.cpp
index 350e20f0137..35c8cd8fccb 100644
--- a/src/core/qgsconditionalstyle.cpp
+++ b/src/core/qgsconditionalstyle.cpp
@@ -38,7 +38,7 @@ bool QgsConditionalLayerStyles::writeXml( QDomNode &node, QDomDocument &doc ) co
 {
   QDomElement stylesel = doc.createElement( "conditionalstyles" );
   QDomElement rowel = doc.createElement( "rowstyles" );
-  foreach ( QgsConditionalStyle style, mRowStyles )
+  foreach ( const QgsConditionalStyle& style, mRowStyles )
   {
     style.writeXml( rowel, doc );
   }
@@ -51,7 +51,7 @@ bool QgsConditionalLayerStyles::writeXml( QDomNode &node, QDomDocument &doc ) co
     QDomElement fieldel = doc.createElement( "fieldstyle" );
     fieldel.setAttribute( "fieldname", field );
     QgsConditionalStyles styles = mFieldStyles[field];
-    foreach ( QgsConditionalStyle style, styles )
+    foreach ( const QgsConditionalStyle& style, styles )
     {
       style.writeXml( fieldel, doc );
     }
@@ -225,7 +225,7 @@ bool QgsConditionalStyle::validTextColor() const
 QList<QgsConditionalStyle> QgsConditionalStyle::matchingConditionalStyles( QList<QgsConditionalStyle> styles, QVariant value,  QgsExpressionContext& context )
 {
   QList<QgsConditionalStyle> matchingstyles;
-  foreach ( QgsConditionalStyle style, styles )
+  foreach ( const QgsConditionalStyle& style, styles )
   {
     if ( style.matches( value, context ) )
       matchingstyles.append( style );
@@ -235,7 +235,7 @@ QList<QgsConditionalStyle> QgsConditionalStyle::matchingConditionalStyles( QList
 
 QgsConditionalStyle QgsConditionalStyle::matchingConditionalStyle( QList<QgsConditionalStyle> styles, QVariant value,  QgsExpressionContext& context )
 {
-  foreach ( QgsConditionalStyle style, styles )
+  foreach ( const QgsConditionalStyle& style, styles )
   {
     if ( style.matches( value, context ) )
       return style;
@@ -246,7 +246,7 @@ QgsConditionalStyle QgsConditionalStyle::matchingConditionalStyle( QList<QgsCond
 QgsConditionalStyle QgsConditionalStyle::compressStyles( QList<QgsConditionalStyle> styles )
 {
   QgsConditionalStyle style;
-  foreach ( QgsConditionalStyle s, styles )
+  foreach ( const QgsConditionalStyle& s, styles )
   {
     style.setFont( s.font() );
     if ( s.backgroundColor().isValid() && s.backgroundColor().alpha() != 0 )
@@ -259,7 +259,7 @@ QgsConditionalStyle QgsConditionalStyle::compressStyles( QList<QgsConditionalSty
   return style;
 }
 
-bool QgsConditionalStyle::writeXml( QDomNode &node, QDomDocument &doc )
+bool QgsConditionalStyle::writeXml( QDomNode &node, QDomDocument &doc ) const
 {
   QDomElement stylesel = doc.createElement( "style" );
   stylesel.setAttribute( "rule", mRule );
diff --git a/src/core/qgsconditionalstyle.h b/src/core/qgsconditionalstyle.h
index 317095fcd2c..4e241b012bd 100644
--- a/src/core/qgsconditionalstyle.h
+++ b/src/core/qgsconditionalstyle.h
@@ -225,7 +225,7 @@ class CORE_EXPORT QgsConditionalStyle
 
     /** Write vector conditional style specific state from layer Dom node.
      */
-    virtual bool writeXml( QDomNode & node, QDomDocument & doc );
+    virtual bool writeXml( QDomNode & node, QDomDocument & doc ) const;
 
 
   private:
diff --git a/src/core/qgscoordinatereferencesystem.cpp b/src/core/qgscoordinatereferencesystem.cpp
index 2c8a27a7b5a..93748331ac8 100644
--- a/src/core/qgscoordinatereferencesystem.cpp
+++ b/src/core/qgscoordinatereferencesystem.cpp
@@ -622,7 +622,7 @@ bool QgsCoordinateReferenceSystem::createFromProj4( const QString &theProj4Strin
     // also with parameters containing spaces (e.g. +nadgrids)
     // make sure result is trimmed (#5598)
     QStringList myParams;
-    foreach ( QString param, myProj4String.split( QRegExp( "\\s+(?=\\+)" ), QString::SkipEmptyParts ) )
+    foreach ( const QString& param, myProj4String.split( QRegExp( "\\s+(?=\\+)" ), QString::SkipEmptyParts ) )
     {
       QString arg = QString( "' '||parameters||' ' LIKE %1" ).arg( quotedValue( QString( "% %1 %" ).arg( param.trimmed() ) ) );
       if ( param.startsWith( "+datum=" ) )
@@ -1623,7 +1623,7 @@ bool QgsCoordinateReferenceSystem::loadIDs( QHash<int, QString> &wkts )
 {
   OGRSpatialReferenceH crs = OSRNewSpatialReference( NULL );
 
-  foreach ( QString csv, QStringList() << "gcs.csv" << "pcs.csv" << "vertcs.csv" << "compdcs.csv" << "geoccs.csv" )
+  foreach ( const QString& csv, QStringList() << "gcs.csv" << "pcs.csv" << "vertcs.csv" << "compdcs.csv" << "geoccs.csv" )
   {
     QString filename = CPLFindFile( "gdal", csv.toUtf8() );
 
diff --git a/src/core/qgsdataitem.cpp b/src/core/qgsdataitem.cpp
index 91b925b1071..3c146590639 100644
--- a/src/core/qgsdataitem.cpp
+++ b/src/core/qgsdataitem.cpp
@@ -775,10 +775,9 @@ QVector<QgsDataItem*> QgsDirectoryItem::createChildren()
 {
   QVector<QgsDataItem*> children;
   QDir dir( mDirPath );
-  QSettings settings;
 
   QStringList entries = dir.entryList( QDir::AllDirs | QDir::NoDotAndDotDot, QDir::Name | QDir::IgnoreCase );
-  foreach ( QString subdir, entries )
+  foreach ( const QString& subdir, entries )
   {
     if ( mRefreshLater )
     {
@@ -796,7 +795,7 @@ QVector<QgsDataItem*> QgsDirectoryItem::createChildren()
   }
 
   QStringList fileEntries = dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot | QDir::Files, QDir::Name );
-  foreach ( QString name, fileEntries )
+  foreach ( const QString& name, fileEntries )
   {
     if ( mRefreshLater )
     {
@@ -931,7 +930,7 @@ QgsDirectoryParamWidget::QgsDirectoryParamWidget( QString path, QWidget* parent
 
   QDir dir( path );
   QStringList entries = dir.entryList( QDir::AllEntries | QDir::NoDotAndDotDot, QDir::Name | QDir::IgnoreCase );
-  foreach ( QString name, entries )
+  foreach ( const QString& name, entries )
   {
     QFileInfo fi( dir.absoluteFilePath( name ) );
     QStringList texts;
@@ -1002,7 +1001,7 @@ QgsDirectoryParamWidget::QgsDirectoryParamWidget( QString path, QWidget* parent
   // hide columns that are not requested
   QSettings settings;
   QList<QVariant> lst = settings.value( "/dataitem/directoryHiddenColumns" ).toList();
-  foreach ( QVariant colVariant, lst )
+  foreach ( const QVariant& colVariant, lst )
   {
     setColumnHidden( colVariant.toInt(), true );
   }
@@ -1083,7 +1082,7 @@ QVector<QgsDataItem*> QgsFavouritesItem::createChildren()
   QSettings settings;
   QStringList favDirs = settings.value( "/browser/favourites", QVariant() ).toStringList();
 
-  foreach ( QString favDir, favDirs )
+  foreach ( const QString& favDir, favDirs )
   {
     QString pathName = pathComponent( favDir );
     QgsDataItem *item = new QgsDirectoryItem( this, favDir, favDir, mPath + "/" + pathName );
@@ -1303,7 +1302,7 @@ QVector<QgsDataItem*> QgsZipItem::createChildren()
   getZipFileList();
 
   // loop over files inside zip
-  foreach ( QString fileName, mZipFileList )
+  foreach ( const QString& fileName, mZipFileList )
   {
     QFileInfo info( fileName );
     tmpPath = mVsiPrefix + mFilePath + "/" + fileName;
diff --git a/src/core/qgsdataitemproviderregistry.cpp b/src/core/qgsdataitemproviderregistry.cpp
index 545619f3ed8..ddf921e632d 100644
--- a/src/core/qgsdataitemproviderregistry.cpp
+++ b/src/core/qgsdataitemproviderregistry.cpp
@@ -55,7 +55,7 @@ QgsDataItemProviderRegistry::QgsDataItemProviderRegistry()
 {
   QStringList providersList = QgsProviderRegistry::instance()->providerList();
 
-  foreach ( QString key, providersList )
+  foreach ( const QString& key, providersList )
   {
     QLibrary *library = QgsProviderRegistry::instance()->providerLibrary( key );
     if ( !library )
diff --git a/src/core/qgsdatasourceuri.cpp b/src/core/qgsdatasourceuri.cpp
index e527bf62aa8..f30dbf564a5 100644
--- a/src/core/qgsdatasourceuri.cpp
+++ b/src/core/qgsdatasourceuri.cpp
@@ -548,9 +548,9 @@ QString QgsDataSourceURI::uri() const
 QByteArray QgsDataSourceURI::encodedUri() const
 {
   QUrl url;
-  foreach ( QString key, mParams.uniqueKeys() )
+  foreach ( const QString& key, mParams.uniqueKeys() )
   {
-    foreach ( QString value, mParams.values( key ) )
+    foreach ( const QString& value, mParams.values( key ) )
     {
       url.addQueryItem( key, value );
     }
@@ -660,7 +660,7 @@ void QgsDataSourceURI::setParam( const QString &key, const QString &value )
 
 void QgsDataSourceURI::setParam( const QString &key, const QStringList &value )
 {
-  foreach ( QString val, value )
+  foreach ( const QString& val, value )
   {
     mParams.insertMulti( key, val );
   }
diff --git a/src/core/qgserror.cpp b/src/core/qgserror.cpp
index 2ccd2a4243c..cb74279388f 100644
--- a/src/core/qgserror.cpp
+++ b/src/core/qgserror.cpp
@@ -64,7 +64,7 @@ QString QgsError::message( QgsErrorMessage::Format theFormat ) const
   }
 #endif
 
-  foreach ( QgsErrorMessage m, mMessageList )
+  foreach ( const QgsErrorMessage& m, mMessageList )
   {
 #ifdef QGISDEBUG
     QString file;
diff --git a/src/core/qgsexpression.cpp b/src/core/qgsexpression.cpp
index f0989dbdb75..cd86477324c 100644
--- a/src/core/qgsexpression.cpp
+++ b/src/core/qgsexpression.cpp
@@ -73,7 +73,7 @@ QgsExpression::Interval QgsExpression::Interval::fromString( QString string )
   map.insert( 0 + MONTHS, QStringList() << "month" << "months" << QObject::tr( "month|months", "list of words separated by | which reference months" ).split( "|" ) );
   map.insert( 0 + YEARS, QStringList() << "year" << "years" << QObject::tr( "year|years", "list of words separated by | which reference years" ).split( "|" ) );
 
-  foreach ( QString match, list )
+  foreach ( const QString& match, list )
   {
     QStringList split = match.split( QRegExp( "\\s+" ) );
     bool ok;
@@ -86,7 +86,7 @@ QgsExpression::Interval QgsExpression::Interval::fromString( QString string )
     bool matched = false;
     foreach ( int duration, map.keys() )
     {
-      foreach ( QString name, map[duration] )
+      foreach ( const QString& name, map[duration] )
       {
         if ( match.contains( name, Qt::CaseInsensitive ) )
         {
@@ -2184,7 +2184,7 @@ int QgsExpression::functionIndex( const QString &name )
   {
     if ( QString::compare( name, Functions()[i]->name(), Qt::CaseInsensitive ) == 0 )
       return i;
-    foreach ( QString alias, Functions()[i]->aliases() )
+    foreach ( const QString& alias, Functions()[i]->aliases() )
     {
       if ( QString::compare( name, alias, Qt::CaseInsensitive ) == 0 )
         return i;
diff --git a/src/core/qgsexpressioncontext.cpp b/src/core/qgsexpressioncontext.cpp
index c965adb6c32..c78a1ab32e4 100644
--- a/src/core/qgsexpressioncontext.cpp
+++ b/src/core/qgsexpressioncontext.cpp
@@ -46,7 +46,7 @@ QgsExpressionContextScope::QgsExpressionContextScope( const QgsExpressionContext
     : mName( other.mName )
     , mVariables( other.mVariables )
 {
-  Q_FOREACH ( QString key, other.mFunctions.keys() )
+  Q_FOREACH ( const QString& key, other.mFunctions.keys() )
   {
     mFunctions.insert( key, other.mFunctions.value( key )->clone() );
   }
@@ -59,7 +59,7 @@ QgsExpressionContextScope& QgsExpressionContextScope::operator=( const QgsExpres
 
   qDeleteAll( mFunctions );
   mFunctions.clear();
-  Q_FOREACH ( QString key, other.mFunctions.keys() )
+  Q_FOREACH ( const QString& key, other.mFunctions.keys() )
   {
     mFunctions.insert( key, other.mFunctions.value( key )->clone() );
   }
@@ -269,7 +269,7 @@ QStringList QgsExpressionContext::filteredVariableNames() const
 {
   QStringList allVariables = variableNames();
   QStringList filtered;
-  Q_FOREACH ( QString variable, allVariables )
+  Q_FOREACH ( const QString& variable, allVariables )
   {
     if ( variable.startsWith( "_" ) )
       continue;
@@ -432,7 +432,7 @@ void QgsExpressionContextUtils::setGlobalVariables( const QgsStringMap &variable
   QList< QVariant > customVariableVariants;
   QList< QVariant > customVariableNames;
 
-  Q_FOREACH ( QString variable, variables.keys() )
+  Q_FOREACH ( const QString& variable, variables.keys() )
   {
     customVariableNames << variable;
     customVariableVariants << variables.value( variable );
@@ -502,7 +502,7 @@ QgsExpressionContextScope* QgsExpressionContextUtils::projectScope()
   QStringList variableValues = project->readListEntry( "Variables", "/variableValues" );
 
   int varIndex = 0;
-  foreach ( QString variableName, variableNames )
+  foreach ( const QString& variableName, variableNames )
   {
     if ( varIndex >= variableValues.length() )
     {
@@ -547,7 +547,7 @@ void QgsExpressionContextUtils::setProjectVariables( const QgsStringMap &variabl
   QStringList variableNames;
   QStringList variableValues;
 
-  Q_FOREACH ( QString variable, variables.keys() )
+  Q_FOREACH ( const QString& variable, variables.keys() )
   {
     variableNames << variable;
     variableValues << variables.value( variable );
@@ -569,7 +569,7 @@ QgsExpressionContextScope* QgsExpressionContextUtils::layerScope( const QgsMapLa
   QStringList variableValues = layer->customProperty( "variableValues" ).toStringList();
 
   int varIndex = 0;
-  foreach ( QString variableName, variableNames )
+  foreach ( const QString& variableName, variableNames )
   {
     if ( varIndex >= variableValues.length() )
     {
@@ -621,7 +621,7 @@ void QgsExpressionContextUtils::setLayerVariables( QgsMapLayer* layer, const Qgs
   QStringList variableNames;
   QStringList variableValues;
 
-  Q_FOREACH ( QString variable, variables.keys() )
+  Q_FOREACH ( const QString& variable, variables.keys() )
   {
     variableNames << variable;
     variableValues << variables.value( variable );
@@ -654,7 +654,7 @@ QgsExpressionContextScope *QgsExpressionContextUtils::compositionScope( const Qg
   QStringList variableValues = composition->customProperty( "variableValues" ).toStringList();
 
   int varIndex = 0;
-  foreach ( QString variableName, variableNames )
+  foreach ( const QString& variableName, variableNames )
   {
     if ( varIndex >= variableValues.length() )
     {
@@ -699,7 +699,7 @@ void QgsExpressionContextUtils::setCompositionVariables( QgsComposition* composi
   QStringList variableNames;
   QStringList variableValues;
 
-  Q_FOREACH ( QString variable, variables.keys() )
+  Q_FOREACH ( const QString& variable, variables.keys() )
   {
     variableNames << variable;
     variableValues << variables.value( variable );
@@ -757,7 +757,7 @@ QgsExpressionContextScope *QgsExpressionContextUtils::composerItemScope( const Q
   QStringList variableValues = composerItem->customProperty( "variableValues" ).toStringList();
 
   int varIndex = 0;
-  foreach ( QString variableName, variableNames )
+  foreach ( const QString& variableName, variableNames )
   {
     if ( varIndex >= variableValues.length() )
     {
@@ -801,7 +801,7 @@ void QgsExpressionContextUtils::setComposerItemVariables( QgsComposerItem* compo
   QStringList variableNames;
   QStringList variableValues;
 
-  Q_FOREACH ( QString variable, variables.keys() )
+  Q_FOREACH ( const QString& variable, variables.keys() )
   {
     variableNames << variable;
     variableValues << variables.value( variable );
diff --git a/src/core/qgsgmlschema.cpp b/src/core/qgsgmlschema.cpp
index 1ee741db1d4..c564a92d0b0 100644
--- a/src/core/qgsgmlschema.cpp
+++ b/src/core/qgsgmlschema.cpp
@@ -106,7 +106,7 @@ bool QgsGmlSchema::parseXSD( const QByteArray &xml )
 
   //QgsDebugMsg( QString( "%1 elemets read" ).arg( elementElements.size() ) );
 
-  foreach ( QDomElement elementElement, elementElements )
+  foreach ( const QDomElement& elementElement, elementElements )
   {
     QString name = elementElement.attribute( "name" );
     QString type = elementElement.attribute( "type" );
@@ -160,7 +160,7 @@ bool QgsGmlSchema::xsdFeatureClass( const QDomElement &element, const QString &
 
   // Supported geometry types
   QStringList geometryPropertyTypes;
-  foreach ( QString geom, mGeometryTypes )
+  foreach ( const QString& geom, mGeometryTypes )
   {
     geometryPropertyTypes << geom + "PropertyType";
   }
@@ -173,7 +173,7 @@ bool QgsGmlSchema::xsdFeatureClass( const QDomElement &element, const QString &
 
   // Add attributes from current comple type
   QList<QDomElement> sequenceElements = domElements( extrest, "sequence.element" );
-  foreach ( QDomElement sequenceElement, sequenceElements )
+  foreach ( const QDomElement& sequenceElement, sequenceElements )
   {
     QString fieldName = sequenceElement.attribute( "name" );
     QString fieldTypeName = stripNS( sequenceElement.attribute( "type" ) );
@@ -316,7 +316,7 @@ QDomElement QgsGmlSchema::domElement( const QDomElement &element, const QString
 QList<QDomElement> QgsGmlSchema::domElements( QList<QDomElement> &elements, const QString & attr, const QString & attrVal )
 {
   QList<QDomElement> list;
-  foreach ( QDomElement el, elements )
+  foreach ( const QDomElement& el, elements )
   {
     if ( el.attribute( attr ) == attrVal )
     {
diff --git a/src/core/qgslegendrenderer.cpp b/src/core/qgslegendrenderer.cpp
index 110875c4e91..c0666e94425 100644
--- a/src/core/qgslegendrenderer.cpp
+++ b/src/core/qgslegendrenderer.cpp
@@ -59,7 +59,7 @@ QSizeF QgsLegendRenderer::paintAndDetermineSize( QPainter* painter )
   qreal maxColumnWidth = 0;
   if ( mSettings.equalColumnWidth() )
   {
-    foreach ( Atom atom, atomList )
+    foreach ( const Atom& atom, atomList )
     {
       maxColumnWidth = qMax( atom.size.width(), maxColumnWidth );
     }
@@ -76,7 +76,7 @@ QSizeF QgsLegendRenderer::paintAndDetermineSize( QPainter* painter )
   double columnMaxHeight = 0;
   qreal columnWidth = 0;
   int column = 0;
-  foreach ( Atom atom, atomList )
+  foreach ( const Atom& atom, atomList )
   {
     if ( atom.column > column )
     {
@@ -262,7 +262,7 @@ void QgsLegendRenderer::setColumns( QList<Atom>& atomList )
   double totalHeight = 0;
   // bool first = true;
   qreal maxAtomHeight = 0;
-  foreach ( Atom atom, atomList )
+  foreach ( const Atom& atom, atomList )
   {
     //if ( !first )
     //{
@@ -449,7 +449,7 @@ QSizeF QgsLegendRenderer::drawAtom( Atom atom, QPainter* painter, QPointF point
 {
   bool first = true;
   QSizeF size = QSizeF( atom.size );
-  foreach ( Nucleon nucleon, atom.nucleons )
+  foreach ( const Nucleon& nucleon, atom.nucleons )
   {
     if ( QgsLayerTreeGroup* groupItem = qobject_cast<QgsLayerTreeGroup*>( nucleon.item ) )
     {
diff --git a/src/core/qgsmaphittest.cpp b/src/core/qgsmaphittest.cpp
index 8e232ebcff4..002eb591564 100644
--- a/src/core/qgsmaphittest.cpp
+++ b/src/core/qgsmaphittest.cpp
@@ -24,7 +24,7 @@ void QgsMapHitTest::run()
   QgsRenderContext context = QgsRenderContext::fromMapSettings( mSettings );
   context.setPainter( &painter ); // we are not going to draw anything, but we still need a working painter
 
-  foreach ( QString layerID, mSettings.layers() )
+  foreach ( const QString& layerID, mSettings.layers() )
   {
     QgsVectorLayer* vl = qobject_cast<QgsVectorLayer*>( QgsMapLayerRegistry::instance()->mapLayer( layerID ) );
     if ( !vl || !vl->rendererV2() )
diff --git a/src/core/qgsmaplayerlegend.cpp b/src/core/qgsmaplayerlegend.cpp
index 0f53e323abc..1937b74d8f9 100644
--- a/src/core/qgsmaplayerlegend.cpp
+++ b/src/core/qgsmaplayerlegend.cpp
@@ -97,7 +97,7 @@ QList<int> QgsMapLayerLegendUtils::legendNodeOrder( QgsLayerTreeLayer* nodeLayer
   int numNodes = _originalLegendNodeCount( nodeLayer );
 
   QList<int> lst;
-  foreach ( QString item, orderStr.split( "," ) )
+  foreach ( const QString& item, orderStr.split( "," ) )
   {
     bool ok;
     int id = item.toInt( &ok );
diff --git a/src/core/qgsmaprenderercache.cpp b/src/core/qgsmaprenderercache.cpp
index aa85c417d08..e97fe68a4d6 100644
--- a/src/core/qgsmaprenderercache.cpp
+++ b/src/core/qgsmaprenderercache.cpp
@@ -35,7 +35,7 @@ void QgsMapRendererCache::clearInternal()
   mScale = 0;
 
   // make sure we are disconnected from all layers
-  foreach ( QString layerId, mCachedImages.keys() )
+  foreach ( const QString& layerId, mCachedImages.keys() )
   {
     QgsMapLayer* layer = QgsMapLayerRegistry::instance()->mapLayer( layerId );
     if ( layer )
diff --git a/src/core/qgsmaprenderercustompainterjob.cpp b/src/core/qgsmaprenderercustompainterjob.cpp
index 5506f1d3af5..dace6296aba 100644
--- a/src/core/qgsmaprenderercustompainterjob.cpp
+++ b/src/core/qgsmaprenderercustompainterjob.cpp
@@ -327,7 +327,7 @@ void QgsMapRendererJob::drawNewLabeling( const QgsMapSettings& settings, QgsRend
 
 void QgsMapRendererJob::updateLayerGeometryCaches()
 {
-  foreach ( QString id, mGeometryCaches.keys() )
+  foreach ( const QString& id, mGeometryCaches.keys() )
   {
     const QgsGeometryCache& cache = mGeometryCaches[id];
     if ( QgsVectorLayer* vl = qobject_cast<QgsVectorLayer*>( QgsMapLayerRegistry::instance()->mapLayer( id ) ) )
diff --git a/src/core/qgsmaprendererjob.cpp b/src/core/qgsmaprendererjob.cpp
index 028c91a68c2..0ec04cb28c3 100644
--- a/src/core/qgsmaprendererjob.cpp
+++ b/src/core/qgsmaprendererjob.cpp
@@ -300,7 +300,7 @@ void QgsMapRendererJob::cleanupJobs( LayerRenderJobs& jobs )
 
     if ( job.renderer )
     {
-      foreach ( QString message, job.renderer->errors() )
+      foreach ( const QString& message, job.renderer->errors() )
         mErrors.append( Error( job.renderer->layerID(), message ) );
 
       delete job.renderer;
diff --git a/src/core/qgsnetworkaccessmanager.cpp b/src/core/qgsnetworkaccessmanager.cpp
index 906190ee699..02db68e8711 100644
--- a/src/core/qgsnetworkaccessmanager.cpp
+++ b/src/core/qgsnetworkaccessmanager.cpp
@@ -60,7 +60,7 @@ class QgsNetworkProxyFactory : public QNetworkProxyFactory
 
       QString url = query.url().toString();
 
-      foreach ( QString exclude, nam->excludeList() )
+      foreach ( const QString& exclude, nam->excludeList() )
       {
         if ( url.startsWith( exclude ) )
         {
diff --git a/src/core/qgsnetworkreplyparser.cpp b/src/core/qgsnetworkreplyparser.cpp
index 5ed40b85fef..a9c0034c312 100644
--- a/src/core/qgsnetworkreplyparser.cpp
+++ b/src/core/qgsnetworkreplyparser.cpp
@@ -119,7 +119,7 @@ QgsNetworkReplyParser::QgsNetworkReplyParser( QNetworkReply *reply )
       QgsDebugMsg( "headers:\n" + headers );
 
       QStringList headerRows = QString( headers ).split( QRegExp( "[\n\r]+" ) );
-      foreach ( QString row, headerRows )
+      foreach ( const QString& row, headerRows )
       {
         QgsDebugMsg( "row = " + row );
         QStringList kv = row.split( ": " );
diff --git a/src/core/qgsobjectcustomproperties.cpp b/src/core/qgsobjectcustomproperties.cpp
index 6d835199e4f..7152556fe24 100644
--- a/src/core/qgsobjectcustomproperties.cpp
+++ b/src/core/qgsobjectcustomproperties.cpp
@@ -132,7 +132,7 @@ void QgsObjectCustomProperties::writeXml( QDomNode& parentNode, QDomDocument& do
     }
     else if ( it.value().canConvert<QStringList>() )
     {
-      foreach ( QString value, it.value().toStringList() )
+      foreach ( const QString& value, it.value().toStringList() )
       {
         QDomElement itemElement = doc.createElement( "value" );
         itemElement.appendChild( doc.createTextNode( value ) );
diff --git a/src/core/qgspallabeling.cpp b/src/core/qgspallabeling.cpp
index 1ff6a3045f6..dabc5234d56 100644
--- a/src/core/qgspallabeling.cpp
+++ b/src/core/qgspallabeling.cpp
@@ -3309,7 +3309,7 @@ int QgsPalLabeling::prepareLayer( QgsVectorLayer* layer, QStringList& attrNames,
       {
         QgsDebugMsgLevel( "Prepare error:" + exp->evalErrorString(), 4 );
       }
-      foreach ( QString name, exp->referencedColumns() )
+      foreach ( const QString& name, exp->referencedColumns() )
       {
         QgsDebugMsgLevel( "REFERENCED COLUMN = " + name, 4 );
         attrNames.append( name );
@@ -3342,7 +3342,7 @@ int QgsPalLabeling::prepareLayer( QgsVectorLayer* layer, QStringList& attrNames,
       QStringList cols = dd->referencedColumns( ctx.expressionContext() ); // <-- prepares any expressions, too
 
       //QgsDebugMsgLevel( QString( "Data defined referenced columns:" ) + cols.join( "," ), 4 );
-      foreach ( QString name, cols )
+      foreach ( const QString& name, cols )
       {
         attrNames.append( name );
       }
@@ -3530,7 +3530,7 @@ QStringList QgsPalLabeling::splitToLines( const QString &text, const QString &wr
   if ( !wrapCharacter.isEmpty() && wrapCharacter != QString( "\n" ) )
   {
     //wrap on both the wrapchr and new line characters
-    foreach ( QString line, text.split( wrapCharacter ) )
+    foreach ( const QString& line, text.split( wrapCharacter ) )
     {
       multiLineSplit.append( line.split( QString( "\n" ) ) );
     }
diff --git a/src/core/qgspluginlayerregistry.cpp b/src/core/qgspluginlayerregistry.cpp
index ffa481fde9b..8fa502cf563 100644
--- a/src/core/qgspluginlayerregistry.cpp
+++ b/src/core/qgspluginlayerregistry.cpp
@@ -75,7 +75,7 @@ QgsPluginLayerRegistry::~QgsPluginLayerRegistry()
   if ( !mPluginLayerTypes.isEmpty() )
   {
     QgsDebugMsg( "QgsPluginLayerRegistry::~QgsPluginLayerRegistry(): creator list not empty" );
-    foreach ( QString typeName, mPluginLayerTypes.keys() )
+    foreach ( const QString& typeName, mPluginLayerTypes.keys() )
       removePluginLayerType( typeName );
   }
 }
diff --git a/src/core/qgsproject.cpp b/src/core/qgsproject.cpp
index 31d27eaba0a..778640c9f63 100644
--- a/src/core/qgsproject.cpp
+++ b/src/core/qgsproject.cpp
@@ -1772,7 +1772,7 @@ QgsLayerTreeGroup *QgsProject::createEmbeddedGroup( const QString &groupName, co
   mLayerTreeRegistryBridge->setEnabled( true );
 
   // consider the layers might be identify disabled in its project
-  foreach ( QString layerId, newGroup->findLayerIds() )
+  foreach ( const QString& layerId, newGroup->findLayerIds() )
   {
     if ( embeddedIdentifyDisabledLayers.contains( layerId ) )
     {
diff --git a/src/core/qgsrelation.cpp b/src/core/qgsrelation.cpp
index c6bc5ff95be..011f2629e48 100644
--- a/src/core/qgsrelation.cpp
+++ b/src/core/qgsrelation.cpp
@@ -97,7 +97,7 @@ void QgsRelation::writeXML( QDomNode &node, QDomDocument &doc ) const
   elem.setAttribute( "referencingLayer", mReferencingLayerId );
   elem.setAttribute( "referencedLayer", mReferencedLayerId );
 
-  Q_FOREACH ( FieldPair fields, mFieldPairs )
+  Q_FOREACH ( const FieldPair& fields, mFieldPairs )
   {
     QDomElement referenceElem = doc.createElement( "fieldRef" );
     referenceElem.setAttribute( "referencingField", fields.first );
diff --git a/src/core/qgssnappingutils.cpp b/src/core/qgssnappingutils.cpp
index 9f96f5fc732..65b67da6ce0 100644
--- a/src/core/qgssnappingutils.cpp
+++ b/src/core/qgssnappingutils.cpp
@@ -460,7 +460,7 @@ void QgsSnappingUtils::readConfigFromProject()
 void QgsSnappingUtils::onLayersWillBeRemoved( QStringList layerIds )
 {
   // remove locators for layers that are going to be deleted
-  foreach ( QString layerId, layerIds )
+  foreach ( const QString& layerId, layerIds )
   {
     for ( LocatorsMap::iterator it = mLocators.begin(); it != mLocators.end(); )
     {
diff --git a/src/core/qgsvectordataprovider.cpp b/src/core/qgsvectordataprovider.cpp
index 00d9908d824..4d50e38ee7f 100644
--- a/src/core/qgsvectordataprovider.cpp
+++ b/src/core/qgsvectordataprovider.cpp
@@ -468,7 +468,7 @@ const QStringList &QgsVectorDataProvider::availableEncodings()
 {
   if ( smEncodings.isEmpty() )
   {
-    foreach ( QString codec, QTextCodec::availableCodecs() )
+    foreach ( const QString& codec, QTextCodec::availableCodecs() )
     {
       smEncodings << codec;
     }
diff --git a/src/core/qgsvectorfilewriter.cpp b/src/core/qgsvectorfilewriter.cpp
index a4aa3355ce7..e39511633b0 100644
--- a/src/core/qgsvectorfilewriter.cpp
+++ b/src/core/qgsvectorfilewriter.cpp
@@ -192,7 +192,7 @@ QgsVectorFileWriter::QgsVectorFileWriter(
     {
       QStringList allExts = exts.split( " ", QString::SkipEmptyParts );
       bool found = false;
-      foreach ( QString ext, allExts )
+      foreach ( const QString& ext, allExts )
       {
         if ( vectorFileName.endsWith( "." + ext, Qt::CaseInsensitive ) )
         {
@@ -2099,7 +2099,7 @@ bool QgsVectorFileWriter::deleteShapeFile( QString theFileName )
   }
 
   bool ok = true;
-  foreach ( QString file, dir.entryList( filter ) )
+  foreach ( const QString& file, dir.entryList( filter ) )
   {
     QFile f( dir.canonicalPath() + "/" + file );
     if ( !f.remove( ) )
@@ -2202,7 +2202,7 @@ QMap<QString, QString> QgsVectorFileWriter::ogrDriverList()
     }
   }
 
-  foreach ( QString drvName, writableDrivers )
+  foreach ( const QString& drvName, writableDrivers )
   {
     QString longName;
     QString trLongName;
diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
index aec74af12f8..d4f7bedab43 100644
--- a/src/core/qgsvectorlayer.cpp
+++ b/src/core/qgsvectorlayer.cpp
@@ -323,7 +323,7 @@ void QgsVectorLayer::drawLabels( QgsRenderContext& rendererContext )
            rendererContext.rendererScale() <= mLabel->maxScale() ) ) )
   {
     QgsAttributeList attributes;
-    foreach ( QString attrName, mRendererV2->usedAttributes() )
+    foreach ( const QString& attrName, mRendererV2->usedAttributes() )
     {
       int attrNum = fieldNameIndex( attrName );
       attributes.append( attrNum );
@@ -3290,7 +3290,7 @@ QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression,
     return values;
 
   bool convertOk;
-  foreach ( QVariant value, variantValues )
+  foreach ( const QVariant& value, variantValues )
   {
     double val = value.toDouble( &convertOk );
     if ( convertOk )
diff --git a/src/core/qgsvectorlayerjoinbuffer.cpp b/src/core/qgsvectorlayerjoinbuffer.cpp
index c860e9c70c1..407e4d0d9be 100644
--- a/src/core/qgsvectorlayerjoinbuffer.cpp
+++ b/src/core/qgsvectorlayerjoinbuffer.cpp
@@ -287,7 +287,7 @@ void QgsVectorLayerJoinBuffer::writeXml( QDomNode& layer_node, QDomDocument& doc
     if ( joinIt->joinFieldNamesSubset() )
     {
       QDomElement subsetElem = document.createElement( "joinFieldsSubset" );
-      foreach ( QString fieldName, *joinIt->joinFieldNamesSubset() )
+      foreach ( const QString& fieldName, *joinIt->joinFieldNamesSubset() )
       {
         QDomElement fieldElem = document.createElement( "field" );
         fieldElem.setAttribute( "name", fieldName );
diff --git a/src/core/qgsvisibilitypresetcollection.cpp b/src/core/qgsvisibilitypresetcollection.cpp
index 84843e37dc7..3492c2101ed 100644
--- a/src/core/qgsvisibilitypresetcollection.cpp
+++ b/src/core/qgsvisibilitypresetcollection.cpp
@@ -240,7 +240,7 @@ void QgsVisibilityPresetCollection::writeXML( QDomDocument& doc )
     const PresetRecord& rec = mPresets[grpName];
     QDomElement visPresetElem = doc.createElement( "visibility-preset" );
     visPresetElem.setAttribute( "name", grpName );
-    foreach ( QString layerID, rec.mVisibleLayerIDs )
+    foreach ( const QString& layerID, rec.mVisibleLayerIDs )
     {
       QDomElement layerElem = doc.createElement( "layer" );
       layerElem.setAttribute( "id", layerID );
@@ -249,11 +249,11 @@ void QgsVisibilityPresetCollection::writeXML( QDomDocument& doc )
       visPresetElem.appendChild( layerElem );
     }
 
-    foreach ( QString layerID, rec.mPerLayerCheckedLegendSymbols.keys() )
+    foreach ( const QString& layerID, rec.mPerLayerCheckedLegendSymbols.keys() )
     {
       QDomElement checkedLegendNodesElem = doc.createElement( "checked-legend-nodes" );
       checkedLegendNodesElem.setAttribute( "id", layerID );
-      foreach ( QString checkedLegendNode, rec.mPerLayerCheckedLegendSymbols[layerID] )
+      foreach ( const QString& checkedLegendNode, rec.mPerLayerCheckedLegendSymbols[layerID] )
       {
         QDomElement checkedLegendNodeElem = doc.createElement( "checked-legend-node" );
         checkedLegendNodeElem.setAttribute( "id", checkedLegendNode );
@@ -270,9 +270,9 @@ void QgsVisibilityPresetCollection::writeXML( QDomDocument& doc )
 
 void QgsVisibilityPresetCollection::registryLayersRemoved( QStringList layerIDs )
 {
-  foreach ( QString layerID, layerIDs )
+  foreach ( const QString& layerID, layerIDs )
   {
-    foreach ( QString presetName, mPresets.keys() )
+    foreach ( const QString& presetName, mPresets.keys() )
     {
       PresetRecord& rec = mPresets[presetName];
       rec.mVisibleLayerIDs.remove( layerID );
@@ -290,7 +290,7 @@ void QgsVisibilityPresetCollection::layerStyleRenamed( const QString& oldName, c
 
   QString layerID = styleMgr->layer()->id();
 
-  foreach ( QString presetName, mPresets.keys() )
+  foreach ( const QString& presetName, mPresets.keys() )
   {
     PresetRecord& rec = mPresets[presetName];
 
diff --git a/src/core/raster/qgsrasterinterface.cpp b/src/core/raster/qgsrasterinterface.cpp
index 96dd0e1c72f..f5b1570485f 100644
--- a/src/core/raster/qgsrasterinterface.cpp
+++ b/src/core/raster/qgsrasterinterface.cpp
@@ -107,7 +107,7 @@ bool QgsRasterInterface::hasStatistics( int theBandNo,
   QgsRasterBandStats myRasterBandStats;
   initStatistics( myRasterBandStats, theBandNo, theStats, theExtent, theSampleSize );
 
-  foreach ( QgsRasterBandStats stats, mStatistics )
+  foreach ( const QgsRasterBandStats& stats, mStatistics )
   {
     if ( stats.contains( myRasterBandStats ) )
     {
@@ -130,7 +130,7 @@ QgsRasterBandStats QgsRasterInterface::bandStatistics( int theBandNo,
   QgsRasterBandStats myRasterBandStats;
   initStatistics( myRasterBandStats, theBandNo, theStats, theExtent, theSampleSize );
 
-  foreach ( QgsRasterBandStats stats, mStatistics )
+  foreach ( const QgsRasterBandStats& stats, mStatistics )
   {
     if ( stats.contains( myRasterBandStats ) )
     {
@@ -381,7 +381,7 @@ bool QgsRasterInterface::hasHistogram( int theBandNo,
   QgsRasterHistogram myHistogram;
   initHistogram( myHistogram, theBandNo, theBinCount, theMinimum, theMaximum, theExtent, theSampleSize, theIncludeOutOfRange );
 
-  foreach ( QgsRasterHistogram histogram, mHistograms )
+  foreach ( const QgsRasterHistogram& histogram, mHistograms )
   {
     if ( histogram == myHistogram )
     {
@@ -405,7 +405,7 @@ QgsRasterHistogram QgsRasterInterface::histogram( int theBandNo,
   initHistogram( myHistogram, theBandNo, theBinCount, theMinimum, theMaximum, theExtent, theSampleSize, theIncludeOutOfRange );
 
   // Find cached
-  foreach ( QgsRasterHistogram histogram, mHistograms )
+  foreach ( const QgsRasterHistogram& histogram, mHistograms )
   {
     if ( histogram == myHistogram )
     {
diff --git a/src/core/raster/qgsrasterlayer.cpp b/src/core/raster/qgsrasterlayer.cpp
index fbe83b7d6eb..c41c76b26ee 100644
--- a/src/core/raster/qgsrasterlayer.cpp
+++ b/src/core/raster/qgsrasterlayer.cpp
@@ -1523,7 +1523,7 @@ bool QgsRasterLayer::writeXml( QDomNode & layer_node,
     noDataRangeList.setAttribute( "bandNo", bandNo );
     noDataRangeList.setAttribute( "useSrcNoData", mDataProvider->useSrcNoDataValue( bandNo ) );
 
-    foreach ( QgsRasterRange range, mDataProvider->userNoDataValues( bandNo ) )
+    foreach ( const QgsRasterRange& range, mDataProvider->userNoDataValues( bandNo ) )
     {
       QDomElement noDataRange =  document.createElement( "noDataRange" );
 
diff --git a/src/core/raster/qgsrasterrange.cpp b/src/core/raster/qgsrasterrange.cpp
index 7d5486cf741..74fe5a00879 100644
--- a/src/core/raster/qgsrasterrange.cpp
+++ b/src/core/raster/qgsrasterrange.cpp
@@ -37,7 +37,7 @@ QgsRasterRange::~QgsRasterRange()
 
 bool QgsRasterRange::contains( double value, const QgsRasterRangeList &rangeList )
 {
-  foreach ( QgsRasterRange range, rangeList )
+  foreach ( const QgsRasterRange& range, rangeList )
   {
     if (( value >= range.mMin && value <= range.mMax ) ||
         qgsDoubleNear( value, range.mMin ) ||
diff --git a/src/core/symbology-ng/qgscategorizedsymbolrendererv2.cpp b/src/core/symbology-ng/qgscategorizedsymbolrendererv2.cpp
index 5b4d4be1a5f..52dc44f4bda 100644
--- a/src/core/symbology-ng/qgscategorizedsymbolrendererv2.cpp
+++ b/src/core/symbology-ng/qgscategorizedsymbolrendererv2.cpp
@@ -727,7 +727,7 @@ QgsLegendSymbolListV2 QgsCategorizedSymbolRendererV2::legendSymbolItemsV2() cons
   {
     // check that all symbols that have the same size expression
     QgsDataDefined ddSize;
-    foreach ( QgsRendererCategoryV2 category, mCategories )
+    foreach ( const QgsRendererCategoryV2& category, mCategories )
     {
       const QgsMarkerSymbolV2 * symbol = static_cast<const QgsMarkerSymbolV2 *>( category.symbol() );
       if ( !ddSize.hasDefaultValues() && symbol->dataDefinedSize() != ddSize )
@@ -761,7 +761,7 @@ QgsLegendSymbolListV2 QgsCategorizedSymbolRendererV2::legendSymbolItemsV2() cons
       }
       // now list the categorized symbols
       const QgsLegendSymbolListV2 list2 = QgsFeatureRendererV2::legendSymbolItemsV2() ;
-      foreach ( QgsLegendSymbolItemV2 item, list2 )
+      foreach ( const QgsLegendSymbolItemV2& item, list2 )
         lst << item;
       return lst;
     }
@@ -847,7 +847,7 @@ QString QgsCategorizedSymbolRendererV2::sizeScaleField() const
 void QgsCategorizedSymbolRendererV2::updateSymbols( QgsSymbolV2 * sym )
 {
   int i = 0;
-  foreach ( QgsRendererCategoryV2 cat, mCategories )
+  foreach ( const QgsRendererCategoryV2& cat, mCategories )
   {
     QgsSymbolV2* symbol = sym->clone();
     symbol->setColor( cat.symbol()->color() );
diff --git a/src/core/symbology-ng/qgscolorbrewerpalette.h b/src/core/symbology-ng/qgscolorbrewerpalette.h
index a0479b326be..6a010598bb6 100644
--- a/src/core/symbology-ng/qgscolorbrewerpalette.h
+++ b/src/core/symbology-ng/qgscolorbrewerpalette.h
@@ -28,13 +28,13 @@ class CORE_EXPORT QgsColorBrewerPalette
       QList<QColor> pal;
       QString palette( brewerString );
       QStringList list = palette.split( QChar( '\n' ) );
-      foreach ( QString entry, list )
+      foreach ( const QString& entry, list )
       {
         QStringList items = entry.split( QChar( '-' ) );
         if ( items.count() != 3 || items[0] != schemeName || items[1].toInt() != colors )
           continue;
         QStringList colors = items[2].split( QChar( ' ' ) );
-        foreach ( QString clr, colors )
+        foreach ( const QString& clr, colors )
         {
           pal << QgsSymbolLayerV2Utils::parseColor( clr );
         }
@@ -48,7 +48,7 @@ class CORE_EXPORT QgsColorBrewerPalette
 
       QString palette( brewerString );
       QStringList list = palette.split( QChar( '\n' ) );
-      foreach ( QString entry, list )
+      foreach ( const QString& entry, list )
       {
         QStringList items = entry.split( QChar( '-' ) );
         if ( items.count() != 3 )
@@ -65,7 +65,7 @@ class CORE_EXPORT QgsColorBrewerPalette
 
       QString palette( brewerString );
       QStringList list = palette.split( QChar( '\n' ) );
-      foreach ( QString entry, list )
+      foreach ( const QString& entry, list )
       {
         QStringList items = entry.split( QChar( '-' ) );
         if ( items.count() != 3 || items[0] != schemeName )
diff --git a/src/core/symbology-ng/qgscptcityarchive.cpp b/src/core/symbology-ng/qgscptcityarchive.cpp
index c360ddd565a..e0c8373e553 100644
--- a/src/core/symbology-ng/qgscptcityarchive.cpp
+++ b/src/core/symbology-ng/qgscptcityarchive.cpp
@@ -50,7 +50,7 @@ QgsCptCityArchive::QgsCptCityArchive( QString archiveName, QString baseDir )
 
   // make Author items
   QgsCptCityDirectoryItem* dirItem = 0;
-  foreach ( QString path, QDir( mBaseDir ).entryList( QDir::Dirs | QDir::NoDotAndDotDot, QDir::Name ) )
+  foreach ( const QString& path, QDir( mBaseDir ).entryList( QDir::Dirs | QDir::NoDotAndDotDot, QDir::Name ) )
   {
     if ( path == "selections" )
       continue;
@@ -66,7 +66,7 @@ QgsCptCityArchive::QgsCptCityArchive( QString archiveName, QString baseDir )
   QgsCptCitySelectionItem* selItem = 0;
   QDir seldir( mBaseDir + "/" + "selections" );
   QgsDebugMsg( "populating selection from " + seldir.path() );
-  foreach ( QString selfile, seldir.entryList( QStringList( "*.xml" ), QDir::Files ) )
+  foreach ( const QString& selfile, seldir.entryList( QStringList( "*.xml" ), QDir::Files ) )
   {
     QgsDebugMsg( "file= " + seldir.path() + "/" + selfile );
     selItem = new QgsCptCitySelectionItem( NULL, QFileInfo( selfile ).baseName(),
@@ -459,7 +459,7 @@ void QgsCptCityArchive::initArchives( bool loadAll )
   if ( loadAll )
   {
     QDir dir( baseDir );
-    foreach ( QString entry, dir.entryList( QStringList( "cpt-city*" ), QDir::Dirs ) )
+    foreach ( const QString& entry, dir.entryList( QStringList( "cpt-city*" ), QDir::Dirs ) )
     {
       if ( QFile::exists( baseDir + "/" + entry + "/VERSION.xml" ) )
         archivesMap[ entry ] = baseDir + "/" + entry;
@@ -951,7 +951,7 @@ QVector<QgsCptCityDataItem*> QgsCptCityDirectoryItem::createChildren()
   }
 
   // add children dirs
-  foreach ( QString childPath, dirEntries() )
+  foreach ( const QString& childPath, dirEntries() )
   {
     QgsCptCityDataItem* childItem =
       QgsCptCityDirectoryItem::dataItem( this, childPath, mPath + "/" + childPath );
diff --git a/src/core/symbology-ng/qgsfillsymbollayerv2.cpp b/src/core/symbology-ng/qgsfillsymbollayerv2.cpp
index c740be667e1..36c7f487f83 100644
--- a/src/core/symbology-ng/qgsfillsymbollayerv2.cpp
+++ b/src/core/symbology-ng/qgsfillsymbollayerv2.cpp
@@ -2703,7 +2703,7 @@ void QgsLinePatternFillSymbolLayer::applyPattern( const QgsSymbolV2RenderContext
     polygons.append( QPolygonF() << p5 << p6 );
   }
 
-  foreach ( QPolygonF polygon, polygons )
+  foreach ( const QPolygonF& polygon, polygons )
   {
     fillLineSymbol->renderPolyline( polygon, context.feature(), lineRenderContext, -1, context.selected() );
   }
diff --git a/src/core/symbology-ng/qgsgraduatedsymbolrendererv2.cpp b/src/core/symbology-ng/qgsgraduatedsymbolrendererv2.cpp
index b6c1c475a4c..ed2a3c0d7c3 100644
--- a/src/core/symbology-ng/qgsgraduatedsymbolrendererv2.cpp
+++ b/src/core/symbology-ng/qgsgraduatedsymbolrendererv2.cpp
@@ -1182,7 +1182,7 @@ QgsLegendSymbolListV2 QgsGraduatedSymbolRendererV2::legendSymbolItemsV2() const
   {
     // check that all symbols that have the same size expression
     QgsDataDefined ddSize;
-    foreach ( QgsRendererRangeV2 range, mRanges )
+    foreach ( const QgsRendererRangeV2& range, mRanges )
     {
       const QgsMarkerSymbolV2 * symbol = static_cast<const QgsMarkerSymbolV2 *>( range.symbol() );
       if ( !ddSize.hasDefaultValues() && symbol->dataDefinedSize() != ddSize )
@@ -1216,7 +1216,7 @@ QgsLegendSymbolListV2 QgsGraduatedSymbolRendererV2::legendSymbolItemsV2() const
       }
       // now list the graduated symbols
       const QgsLegendSymbolListV2 list2 = QgsFeatureRendererV2::legendSymbolItemsV2() ;
-      foreach ( QgsLegendSymbolItemV2 item, list2 )
+      foreach ( const QgsLegendSymbolItemV2& item, list2 )
         list << item;
       return list;
     }
@@ -1316,7 +1316,7 @@ void QgsGraduatedSymbolRendererV2::updateColorRamp( QgsVectorColorRampV2 *ramp,
 
   if ( mSourceColorRamp )
   {
-    foreach ( QgsRendererRangeV2 range, mRanges )
+    foreach ( const QgsRendererRangeV2& range, mRanges )
     {
       QgsSymbolV2 *symbol = range.symbol() ? range.symbol()->clone() : 0;
       if ( symbol )
@@ -1341,7 +1341,7 @@ void QgsGraduatedSymbolRendererV2::updateSymbols( QgsSymbolV2 *sym )
     return;
 
   int i = 0;
-  foreach ( QgsRendererRangeV2 range, mRanges )
+  foreach ( const QgsRendererRangeV2& range, mRanges )
   {
     QScopedPointer<QgsSymbolV2> symbol( sym->clone() );
     if ( mGraduatedMethod == GraduatedColor )
diff --git a/src/core/symbology-ng/qgsrendererv2registry.cpp b/src/core/symbology-ng/qgsrendererv2registry.cpp
index 17e0849fd5c..12957f2f35a 100644
--- a/src/core/symbology-ng/qgsrendererv2registry.cpp
+++ b/src/core/symbology-ng/qgsrendererv2registry.cpp
@@ -59,7 +59,7 @@ QgsRendererV2Registry::QgsRendererV2Registry()
 
 QgsRendererV2Registry::~QgsRendererV2Registry()
 {
-  foreach ( QString name, mRenderers.keys() )
+  foreach ( const QString& name, mRenderers.keys() )
   {
     delete mRenderers[name];
   }
diff --git a/src/core/symbology-ng/qgsstylev2.cpp b/src/core/symbology-ng/qgsstylev2.cpp
index a08e87e3816..096f513d488 100644
--- a/src/core/symbology-ng/qgsstylev2.cpp
+++ b/src/core/symbology-ng/qgsstylev2.cpp
@@ -1124,7 +1124,7 @@ QStringList QgsStyleV2::symbolsOfSmartgroup( StyleEntity type, int id )
       {
         resultNames = type == SymbolEntity ? symbolNames() : colorRampNames();
         QStringList unwanted = symbolsWithTag( type, tagId( param ) );
-        foreach ( QString name, unwanted )
+        foreach ( const QString& name, unwanted )
         {
           resultNames.removeAll( name );
         }
@@ -1133,7 +1133,7 @@ QStringList QgsStyleV2::symbolsOfSmartgroup( StyleEntity type, int id )
       {
         resultNames = type == SymbolEntity ? symbolNames() : colorRampNames();
         QStringList unwanted = symbolsOfGroup( type, groupId( param ) );
-        foreach ( QString name, unwanted )
+        foreach ( const QString& name, unwanted )
         {
           resultNames.removeAll( name );
         }
diff --git a/src/core/symbology-ng/qgssymbollayerv2registry.cpp b/src/core/symbology-ng/qgssymbollayerv2registry.cpp
index 7f0e5659236..f7f1d1ed7c5 100644
--- a/src/core/symbology-ng/qgssymbollayerv2registry.cpp
+++ b/src/core/symbology-ng/qgssymbollayerv2registry.cpp
@@ -60,7 +60,7 @@ QgsSymbolLayerV2Registry::QgsSymbolLayerV2Registry()
 
 QgsSymbolLayerV2Registry::~QgsSymbolLayerV2Registry()
 {
-  foreach ( QString name, mMetadata.keys() )
+  foreach ( const QString& name, mMetadata.keys() )
   {
     delete mMetadata[name];
   }
diff --git a/src/core/symbology-ng/qgssymbollayerv2utils.cpp b/src/core/symbology-ng/qgssymbollayerv2utils.cpp
index d745c7af7fe..77e02a5c583 100644
--- a/src/core/symbology-ng/qgssymbollayerv2utils.cpp
+++ b/src/core/symbology-ng/qgssymbollayerv2utils.cpp
@@ -2722,7 +2722,7 @@ QDomElement QgsSymbolLayerV2Utils::saveSymbols( QgsSymbolV2Map& symbols, QString
 
 void QgsSymbolLayerV2Utils::clearSymbolMap( QgsSymbolV2Map& symbols )
 {
-  foreach ( QString name, symbols.keys() )
+  foreach ( const QString& name, symbols.keys() )
   {
     delete symbols.value( name );
   }
@@ -3520,12 +3520,12 @@ QStringList QgsSymbolLayerV2Utils::listSvgFiles()
   for ( int i = 0; i < svgPaths.size(); i++ )
   {
     QDir dir( svgPaths[i] );
-    foreach ( QString item, dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot ) )
+    foreach ( const QString& item, dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot ) )
     {
       svgPaths.insert( i + 1, dir.path() + "/" + item );
     }
 
-    foreach ( QString item, dir.entryList( QStringList( "*.svg" ), QDir::Files ) )
+    foreach ( const QString& item, dir.entryList( QStringList( "*.svg" ), QDir::Files ) )
     {
       // TODO test if it is correct SVG
       list.append( dir.path() + "/" + item );
@@ -3546,12 +3546,12 @@ QStringList QgsSymbolLayerV2Utils::listSvgFilesAt( QString directory )
   for ( int i = 0; i < svgPaths.size(); i++ )
   {
     QDir dir( svgPaths[i] );
-    foreach ( QString item, dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot ) )
+    foreach ( const QString& item, dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot ) )
     {
       svgPaths.insert( i + 1, dir.path() + "/" + item );
     }
 
-    foreach ( QString item, dir.entryList( QStringList( "*.svg" ), QDir::Files ) )
+    foreach ( const QString& item, dir.entryList( QStringList( "*.svg" ), QDir::Files ) )
     {
       list.append( dir.path() + "/" + item );
     }
diff --git a/src/core/symbology-ng/qgsvectorcolorrampv2.cpp b/src/core/symbology-ng/qgsvectorcolorrampv2.cpp
index d82a8f94203..e950b72fd72 100644
--- a/src/core/symbology-ng/qgsvectorcolorrampv2.cpp
+++ b/src/core/symbology-ng/qgsvectorcolorrampv2.cpp
@@ -61,7 +61,7 @@ QgsVectorColorRampV2* QgsVectorGradientColorRampV2::create( const QgsStringMap&
   QgsGradientStopsList stops;
   if ( props.contains( "stops" ) )
   {
-    foreach ( QString stop, props["stops"].split( ':' ) )
+    foreach ( const QString& stop, props["stops"].split( ':' ) )
     {
       int i = stop.indexOf( ';' );
       if ( i == -1 )