diff --git a/src/analysis/openstreetmap/qgsosmdownload.cpp b/src/analysis/openstreetmap/qgsosmdownload.cpp
index defd1c03302..c5c595792fa 100644
--- a/src/analysis/openstreetmap/qgsosmdownload.cpp
+++ b/src/analysis/openstreetmap/qgsosmdownload.cpp
@@ -84,10 +84,10 @@ bool QgsOSMDownload::start()
 
   mReply = nwam->get( request );
 
-  connect( mReply, SIGNAL( readyRead() ), this, SLOT( onReadyRead() ) );
-  connect( mReply, SIGNAL( error( QNetworkReply::NetworkError ) ), this, SLOT( onError( QNetworkReply::NetworkError ) ) );
-  connect( mReply, SIGNAL( finished() ), this, SLOT( onFinished() ) );
-  connect( mReply, SIGNAL( downloadProgress( qint64, qint64 ) ), this, SIGNAL( downloadProgress( qint64, qint64 ) ) );
+  connect( mReply, &QIODevice::readyRead, this, &QgsOSMDownload::onReadyRead );
+  connect( mReply, static_cast < void ( QNetworkReply::* )( QNetworkReply::NetworkError ) >( &QNetworkReply::error ), this, &QgsOSMDownload::onError );
+  connect( mReply, &QNetworkReply::finished, this, &QgsOSMDownload::onFinished );
+  connect( mReply, &QNetworkReply::downloadProgress, this, &QgsOSMDownload::downloadProgress );
 
   return true;
 }
diff --git a/src/app/composer/qgsatlascompositionwidget.cpp b/src/app/composer/qgsatlascompositionwidget.cpp
index 13db79bc599..7ca575976ca 100644
--- a/src/app/composer/qgsatlascompositionwidget.cpp
+++ b/src/app/composer/qgsatlascompositionwidget.cpp
@@ -34,16 +34,16 @@ QgsAtlasCompositionWidget::QgsAtlasCompositionWidget( QWidget *parent, QgsCompos
 
   connect( mAtlasCoverageLayerComboBox, &QgsMapLayerComboBox::layerChanged, mAtlasSortFeatureKeyComboBox, &QgsFieldComboBox::setLayer );
   connect( mAtlasCoverageLayerComboBox, &QgsMapLayerComboBox::layerChanged, mPageNameWidget, &QgsFieldExpressionWidget::setLayer );
-  connect( mAtlasCoverageLayerComboBox, SIGNAL( layerChanged( QgsMapLayer * ) ), this, SLOT( changeCoverageLayer( QgsMapLayer * ) ) );
-  connect( mAtlasSortFeatureKeyComboBox, SIGNAL( fieldChanged( QString ) ), this, SLOT( changesSortFeatureField( QString ) ) );
-  connect( mPageNameWidget, SIGNAL( fieldChanged( QString, bool ) ), this, SLOT( pageNameExpressionChanged( QString, bool ) ) );
+  connect( mAtlasCoverageLayerComboBox, &QgsMapLayerComboBox::layerChanged, this, &QgsAtlasCompositionWidget::changeCoverageLayer );
+  connect( mAtlasSortFeatureKeyComboBox, &QgsFieldComboBox::fieldChanged, this, &QgsAtlasCompositionWidget::changesSortFeatureField );
+  connect( mPageNameWidget, static_cast < void ( QgsFieldExpressionWidget::* )( const QString &, bool ) > ( &QgsFieldExpressionWidget::fieldChanged ), this, &QgsAtlasCompositionWidget::pageNameExpressionChanged );
 
   // Sort direction
   mAtlasSortFeatureDirectionButton->setEnabled( false );
   mAtlasSortFeatureKeyComboBox->setEnabled( false );
 
   // connect to updates
-  connect( &mComposition->atlasComposition(), SIGNAL( parameterChanged() ), this, SLOT( updateGuiElements() ) );
+  connect( &mComposition->atlasComposition(), &QgsAtlasComposition::parameterChanged, this, &QgsAtlasCompositionWidget::updateGuiElements );
 
   mPageNameWidget->registerExpressionContextGenerator( mComposition );
 
diff --git a/src/app/composer/qgsattributeselectiondialog.cpp b/src/app/composer/qgsattributeselectiondialog.cpp
index 8914382859e..911bb683cc4 100644
--- a/src/app/composer/qgsattributeselectiondialog.cpp
+++ b/src/app/composer/qgsattributeselectiondialog.cpp
@@ -120,7 +120,7 @@ QWidget *QgsComposerColumnSourceDelegate::createEditor( QWidget *parent, const Q
   fieldExpression->registerExpressionContextGenerator( this );
 
   //listen out for field changes
-  connect( fieldExpression, SIGNAL( fieldChanged( QString ) ), this, SLOT( commitAndCloseEditor() ) );
+  connect( fieldExpression, static_cast < void ( QgsFieldExpressionWidget::* )( const QString & ) >( &QgsFieldExpressionWidget::fieldChanged ), this, [ = ] { const_cast< QgsComposerColumnSourceDelegate * >( this )->commitAndCloseEditor(); } );
   return fieldExpression;
 }
 
diff --git a/src/app/composer/qgscomposerarrowwidget.cpp b/src/app/composer/qgscomposerarrowwidget.cpp
index 5cebb5e4652..1edb861bcaf 100644
--- a/src/app/composer/qgscomposerarrowwidget.cpp
+++ b/src/app/composer/qgscomposerarrowwidget.cpp
@@ -57,7 +57,7 @@ QgsComposerArrowWidget::QgsComposerArrowWidget( QgsComposerArrow *arrow ): QgsCo
 
   if ( arrow )
   {
-    connect( arrow, SIGNAL( itemChanged() ), this, SLOT( setGuiElementValues() ) );
+    connect( arrow, &QgsComposerObject::itemChanged, this, &QgsComposerArrowWidget::setGuiElementValues );
   }
 }
 
@@ -339,7 +339,7 @@ void QgsComposerArrowWidget::on_mLineStyleButton_clicked()
   symbolContext.setExpressionContext( &context );
   d->setContext( symbolContext );
 
-  connect( d, SIGNAL( widgetChanged() ), this, SLOT( updateLineStyleFromWidget() ) );
+  connect( d, &QgsPanelWidget::widgetChanged, this, &QgsComposerArrowWidget::updateLineStyleFromWidget );
   connect( d, &QgsPanelWidget::panelAccepted, this, &QgsComposerArrowWidget::cleanUpLineStyleSelector );
   openPanel( d );
   mArrow->beginCommand( tr( "Arrow line style changed" ) );
diff --git a/src/app/composer/qgscomposerattributetablewidget.cpp b/src/app/composer/qgscomposerattributetablewidget.cpp
index f5e3afdfdbc..1ed428ed284 100644
--- a/src/app/composer/qgscomposerattributetablewidget.cpp
+++ b/src/app/composer/qgscomposerattributetablewidget.cpp
@@ -58,14 +58,14 @@ QgsComposerAttributeTableWidget::QgsComposerAttributeTableWidget( QgsComposerAtt
   toggleAtlasSpecificControls( atlasEnabled );
 
   //update relations combo when relations modified in project
-  connect( QgsProject::instance()->relationManager(), SIGNAL( changed() ), this, SLOT( updateRelationsCombo() ) );
+  connect( QgsProject::instance()->relationManager(), &QgsRelationManager::changed, this, &QgsComposerAttributeTableWidget::updateRelationsCombo );
 
   mLayerComboBox->setFilters( QgsMapLayerProxyModel::VectorLayer );
-  connect( mLayerComboBox, SIGNAL( layerChanged( QgsMapLayer * ) ), this, SLOT( changeLayer( QgsMapLayer * ) ) );
+  connect( mLayerComboBox, &QgsMapLayerComboBox::layerChanged, this, &QgsComposerAttributeTableWidget::changeLayer );
 
   mComposerMapComboBox->setComposition( mComposerTable->composition() );
   mComposerMapComboBox->setItemType( QgsComposerItem::ComposerMap );
-  connect( mComposerMapComboBox, SIGNAL( itemChanged( QgsComposerItem * ) ), this, SLOT( composerMapChanged( QgsComposerItem * ) ) );
+  connect( mComposerMapComboBox, &QgsComposerItemComboBox::itemChanged, this, &QgsComposerAttributeTableWidget::composerMapChanged );
 
   mHeaderFontColorButton->setColorDialogTitle( tr( "Select header font color" ) );
   mHeaderFontColorButton->setAllowAlpha( true );
@@ -87,15 +87,15 @@ QgsComposerAttributeTableWidget::QgsComposerAttributeTableWidget( QgsComposerAtt
 
   if ( mComposerTable )
   {
-    QObject::connect( mComposerTable, SIGNAL( changed() ), this, SLOT( updateGuiElements() ) );
+    connect( mComposerTable, &QgsComposerMultiFrame::changed, this, &QgsComposerAttributeTableWidget::updateGuiElements );
 
     QgsAtlasComposition *atlas = atlasComposition();
     if ( atlas )
     {
       // repopulate relations combo box if atlas layer changes
-      connect( atlas, SIGNAL( coverageLayerChanged( QgsVectorLayer * ) ),
-               this, SLOT( updateRelationsCombo() ) );
-      connect( atlas, SIGNAL( toggled( bool ) ), this, SLOT( atlasToggled() ) );
+      connect( atlas, &QgsAtlasComposition::coverageLayerChanged,
+               this, &QgsComposerAttributeTableWidget::updateRelationsCombo );
+      connect( atlas, &QgsAtlasComposition::toggled, this, &QgsComposerAttributeTableWidget::atlasToggled );
     }
   }
 
diff --git a/src/app/composer/qgscomposerhtmlwidget.cpp b/src/app/composer/qgscomposerhtmlwidget.cpp
index 5de6b9e065d..eb0fee73de9 100644
--- a/src/app/composer/qgscomposerhtmlwidget.cpp
+++ b/src/app/composer/qgscomposerhtmlwidget.cpp
@@ -36,12 +36,12 @@ QgsComposerHtmlWidget::QgsComposerHtmlWidget( QgsComposerHtml *html, QgsComposer
 
   //setup html editor
   mHtmlEditor = new QgsCodeEditorHTML( this );
-  connect( mHtmlEditor, SIGNAL( textChanged() ), this, SLOT( htmlEditorChanged() ) );
+  connect( mHtmlEditor, &QsciScintilla::textChanged, this, &QgsComposerHtmlWidget::htmlEditorChanged );
   htmlEditorLayout->addWidget( mHtmlEditor );
 
   //setup stylesheet editor
   mStylesheetEditor = new QgsCodeEditorCSS( this );
-  connect( mStylesheetEditor, SIGNAL( textChanged() ), this, SLOT( stylesheetEditorChanged() ) );
+  connect( mStylesheetEditor, &QsciScintilla::textChanged, this, &QgsComposerHtmlWidget::stylesheetEditorChanged );
   stylesheetEditorLayout->addWidget( mStylesheetEditor );
 
   blockSignals( true );
@@ -54,7 +54,7 @@ QgsComposerHtmlWidget::QgsComposerHtmlWidget( QgsComposerHtml *html, QgsComposer
 
   if ( mHtml )
   {
-    QObject::connect( mHtml, SIGNAL( changed() ), this, SLOT( setGuiElementValues() ) );
+    connect( mHtml, &QgsComposerMultiFrame::changed, this, &QgsComposerHtmlWidget::setGuiElementValues );
   }
 
   //embed widget for general options
diff --git a/src/app/composer/qgscomposerimageexportoptionsdialog.cpp b/src/app/composer/qgscomposerimageexportoptionsdialog.cpp
index 3793709ed76..e89f57e39a8 100644
--- a/src/app/composer/qgscomposerimageexportoptionsdialog.cpp
+++ b/src/app/composer/qgscomposerimageexportoptionsdialog.cpp
@@ -27,7 +27,7 @@ QgsComposerImageExportOptionsDialog::QgsComposerImageExportOptionsDialog( QWidge
 {
   setupUi( this );
 
-  connect( mClipToContentGroupBox, SIGNAL( toggled( bool ) ), this, SLOT( clipToContentsToggled( bool ) ) );
+  connect( mClipToContentGroupBox, &QGroupBox::toggled, this, &QgsComposerImageExportOptionsDialog::clipToContentsToggled );
 
   QgsSettings settings;
   restoreGeometry( settings.value( QStringLiteral( "Windows/ComposerImageExportOptionsDialog/geometry" ) ).toByteArray() );
diff --git a/src/app/composer/qgscomposeritemwidget.cpp b/src/app/composer/qgscomposeritemwidget.cpp
index 5d620e76354..ad6c27b4ee2 100644
--- a/src/app/composer/qgscomposeritemwidget.cpp
+++ b/src/app/composer/qgscomposeritemwidget.cpp
@@ -24,6 +24,7 @@
 #include "qgspropertyoverridebutton.h"
 #include "qgsexpressioncontext.h"
 #include "qgsproject.h"
+#include "qgsvectorlayer.h"
 #include <QColorDialog>
 #include <QPen>
 
@@ -34,9 +35,9 @@ QgsComposerConfigObject::QgsComposerConfigObject( QWidget *parent, QgsComposerOb
   : QObject( parent )
   , mComposerObject( composerObject )
 {
-  connect( atlasComposition(), SIGNAL( coverageLayerChanged( QgsVectorLayer * ) ),
-           this, SLOT( updateDataDefinedButtons() ) );
-  connect( atlasComposition(), SIGNAL( toggled( bool ) ), this, SLOT( updateDataDefinedButtons() ) );
+  connect( atlasComposition(), &QgsAtlasComposition::coverageLayerChanged,
+           this, [ = ] { updateDataDefinedButtons(); } );
+  connect( atlasComposition(), &QgsAtlasComposition::toggled, this, &QgsComposerConfigObject::updateDataDefinedButtons );
 }
 
 QgsComposerConfigObject::~QgsComposerConfigObject()
@@ -165,20 +166,20 @@ QgsComposerItemWidget::QgsComposerItemWidget( QWidget *parent, QgsComposerItem *
   initializeDataDefinedButtons();
 
   setValuesForGuiElements();
-  connect( mItem->composition(), SIGNAL( paperSizeChanged() ), this, SLOT( setValuesForGuiPositionElements() ) );
-  connect( mItem, SIGNAL( sizeChanged() ), this, SLOT( setValuesForGuiPositionElements() ) );
-  connect( mItem, SIGNAL( itemChanged() ), this, SLOT( setValuesForGuiNonPositionElements() ) );
+  connect( mItem->composition(), &QgsComposition::paperSizeChanged, this, &QgsComposerItemWidget::setValuesForGuiPositionElements );
+  connect( mItem, &QgsComposerItem::sizeChanged, this, &QgsComposerItemWidget::setValuesForGuiPositionElements );
+  connect( mItem, &QgsComposerObject::itemChanged, this, &QgsComposerItemWidget::setValuesForGuiNonPositionElements );
 
-  connect( mTransparencySlider, SIGNAL( valueChanged( int ) ), mTransparencySpnBx, SLOT( setValue( int ) ) );
+  connect( mTransparencySlider, &QAbstractSlider::valueChanged, mTransparencySpnBx, &QSpinBox::setValue );
 
   updateVariables();
-  connect( mVariableEditor, SIGNAL( scopeChanged() ), this, SLOT( variablesChanged() ) );
+  connect( mVariableEditor, &QgsVariableEditorWidget::scopeChanged, this, &QgsComposerItemWidget::variablesChanged );
   // listen out for variable edits
   connect( QgsApplication::instance(), &QgsApplication::customVariablesChanged, this, &QgsComposerItemWidget::updateVariables );
   connect( QgsProject::instance(), &QgsProject::customVariablesChanged, this, &QgsComposerItemWidget::updateVariables );
 
   if ( mItem->composition() )
-    connect( mItem->composition(), SIGNAL( variablesChanged() ), this, SLOT( updateVariables() ) );
+    connect( mItem->composition(), &QgsComposition::variablesChanged, this, &QgsComposerItemWidget::updateVariables );
 }
 
 QgsComposerItemWidget::~QgsComposerItemWidget()
diff --git a/src/app/composer/qgscomposerlabelwidget.cpp b/src/app/composer/qgscomposerlabelwidget.cpp
index ef1a0f1fb7b..2afce2f58e0 100644
--- a/src/app/composer/qgscomposerlabelwidget.cpp
+++ b/src/app/composer/qgscomposerlabelwidget.cpp
@@ -44,7 +44,7 @@ QgsComposerLabelWidget::QgsComposerLabelWidget( QgsComposerLabel *label ): QgsCo
   if ( mComposerLabel )
   {
     setGuiElementValues();
-    connect( mComposerLabel, SIGNAL( itemChanged() ), this, SLOT( setGuiElementValues() ) );
+    connect( mComposerLabel, &QgsComposerObject::itemChanged, this, &QgsComposerLabelWidget::setGuiElementValues );
   }
 }
 
diff --git a/src/app/composer/qgscomposerlegendwidget.cpp b/src/app/composer/qgscomposerlegendwidget.cpp
index 0a2c95f7f24..e0994f49e7e 100644
--- a/src/app/composer/qgscomposerlegendwidget.cpp
+++ b/src/app/composer/qgscomposerlegendwidget.cpp
@@ -81,7 +81,7 @@ QgsComposerLegendWidget::QgsComposerLegendWidget( QgsComposerLegend *legend )
   if ( legend )
     mMapComboBox->setComposition( legend->composition() );
   mMapComboBox->setItemType( QgsComposerItem::ComposerMap );
-  connect( mMapComboBox, SIGNAL( itemChanged( QgsComposerItem * ) ), this, SLOT( composerMapChanged( QgsComposerItem * ) ) );
+  connect( mMapComboBox, &QgsComposerItemComboBox::itemChanged, this, &QgsComposerLegendWidget::composerMapChanged );
 
   //add widget for item properties
   QgsComposerItemWidget *itemPropertiesWidget = new QgsComposerItemWidget( this, legend );
@@ -93,12 +93,12 @@ QgsComposerLegendWidget::QgsComposerLegendWidget( QgsComposerLegend *legend )
   {
     mItemTreeView->setModel( legend->model() );
     mItemTreeView->setMenuProvider( new QgsComposerLegendMenuProvider( mItemTreeView, this ) );
-    connect( legend, SIGNAL( itemChanged() ), this, SLOT( setGuiElements() ) );
+    connect( legend, &QgsComposerObject::itemChanged, this, &QgsComposerLegendWidget::setGuiElements );
     mWrapCharLineEdit->setText( legend->wrapChar() );
 
     // connect atlas state to the filter legend by atlas checkbox
-    connect( &legend->composition()->atlasComposition(), SIGNAL( toggled( bool ) ), this, SLOT( updateFilterLegendByAtlasButton() ) );
-    connect( &legend->composition()->atlasComposition(), SIGNAL( coverageLayerChanged( QgsVectorLayer * ) ), this, SLOT( updateFilterLegendByAtlasButton() ) );
+    connect( &legend->composition()->atlasComposition(), &QgsAtlasComposition::toggled, this, &QgsComposerLegendWidget::updateFilterLegendByAtlasButton );
+    connect( &legend->composition()->atlasComposition(), &QgsAtlasComposition::coverageLayerChanged, this, &QgsComposerLegendWidget::updateFilterLegendByAtlasButton );
   }
 
   registerDataDefinedButton( mLegendTitleDDBtn, QgsComposerObject::LegendTitle );
@@ -106,8 +106,8 @@ QgsComposerLegendWidget::QgsComposerLegendWidget( QgsComposerLegend *legend )
 
   setGuiElements();
 
-  connect( mItemTreeView->selectionModel(), SIGNAL( currentChanged( const QModelIndex &, const QModelIndex & ) ),
-           this, SLOT( selectedChanged( const QModelIndex &, const QModelIndex & ) ) );
+  connect( mItemTreeView->selectionModel(), &QItemSelectionModel::currentChanged,
+           this, &QgsComposerLegendWidget::selectedChanged );
 }
 
 QgsComposerLegendWidget::QgsComposerLegendWidget(): QgsComposerItemBaseWidget( nullptr, nullptr ), mLegend( nullptr )
diff --git a/src/app/composer/qgscomposermapgridwidget.cpp b/src/app/composer/qgscomposermapgridwidget.cpp
index fcaddb97bc6..563603b9caa 100644
--- a/src/app/composer/qgscomposermapgridwidget.cpp
+++ b/src/app/composer/qgscomposermapgridwidget.cpp
@@ -665,8 +665,8 @@ void QgsComposerMapGridWidget::on_mGridMarkerStyleButton_clicked()
   symbolContext.setExpressionContext( &context );
   d->setContext( symbolContext );
 
-  connect( d, SIGNAL( widgetChanged() ), this, SLOT( updateGridMarkerStyleFromWidget() ) );
-  connect( d, SIGNAL( panelAccepted( QgsPanelWidget * ) ), this, SLOT( cleanUpGridMarkerStyleSelector( QgsPanelWidget * ) ) );
+  connect( d, &QgsPanelWidget::widgetChanged, this, &QgsComposerMapGridWidget::updateGridMarkerStyleFromWidget );
+  connect( d, &QgsPanelWidget::panelAccepted, this, &QgsComposerMapGridWidget::cleanUpGridMarkerStyleSelector );
   openPanel( d );
   mComposerMap->beginCommand( tr( "Grid markers style changed" ) );
 }
diff --git a/src/app/composer/qgscomposermapwidget.cpp b/src/app/composer/qgscomposermapwidget.cpp
index 5019679d92e..5115bcd08e5 100644
--- a/src/app/composer/qgscomposermapwidget.cpp
+++ b/src/app/composer/qgscomposermapwidget.cpp
@@ -69,9 +69,9 @@ QgsComposerMapWidget::QgsComposerMapWidget( QgsComposerMap *composerMap )
 
   // follow preset combo
   mFollowVisibilityPresetCombo->setModel( new QStringListModel( mFollowVisibilityPresetCombo ) );
-  connect( mFollowVisibilityPresetCombo, SIGNAL( currentIndexChanged( int ) ), this, SLOT( followVisibilityPresetSelected( int ) ) );
-  connect( QgsProject::instance()->mapThemeCollection(), SIGNAL( mapThemesChanged() ),
-           this, SLOT( onMapThemesChanged() ) );
+  connect( mFollowVisibilityPresetCombo, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsComposerMapWidget::followVisibilityPresetSelected );
+  connect( QgsProject::instance()->mapThemeCollection(), &QgsMapThemeCollection::mapThemesChanged,
+           this, &QgsComposerMapWidget::onMapThemesChanged );
   onMapThemesChanged();
 
   // keep layers from preset button
@@ -79,20 +79,20 @@ QgsComposerMapWidget::QgsComposerMapWidget( QgsComposerMap *composerMap )
   mLayerListFromPresetButton->setMenu( menuKeepLayers );
   mLayerListFromPresetButton->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionShowAllLayers.svg" ) ) );
   mLayerListFromPresetButton->setToolTip( tr( "Set layer list from a map theme" ) );
-  connect( menuKeepLayers, SIGNAL( aboutToShow() ), this, SLOT( aboutToShowKeepLayersVisibilityPresetsMenu() ) );
+  connect( menuKeepLayers, &QMenu::aboutToShow, this, &QgsComposerMapWidget::aboutToShowKeepLayersVisibilityPresetsMenu );
 
   if ( composerMap )
   {
     mLabel->setText( tr( "Map %1" ).arg( composerMap->id() ) );
 
-    connect( composerMap, SIGNAL( itemChanged() ), this, SLOT( setGuiElementValues() ) );
+    connect( composerMap, &QgsComposerObject::itemChanged, this, &QgsComposerMapWidget::setGuiElementValues );
 
     QgsAtlasComposition *atlas = atlasComposition();
     if ( atlas )
     {
-      connect( atlas, SIGNAL( coverageLayerChanged( QgsVectorLayer * ) ),
-               this, SLOT( atlasLayerChanged( QgsVectorLayer * ) ) );
-      connect( atlas, SIGNAL( toggled( bool ) ), this, SLOT( compositionAtlasToggled( bool ) ) );
+      connect( atlas, &QgsAtlasComposition::coverageLayerChanged,
+               this, &QgsComposerMapWidget::atlasLayerChanged );
+      connect( atlas, &QgsAtlasComposition::toggled, this, &QgsComposerMapWidget::compositionAtlasToggled );
 
       compositionAtlasToggled( atlas->enabled() );
     }
@@ -100,7 +100,7 @@ QgsComposerMapWidget::QgsComposerMapWidget( QgsComposerMap *composerMap )
     mOverviewFrameMapComboBox->setComposition( composerMap->composition() );
     mOverviewFrameMapComboBox->setItemType( QgsComposerItem::ComposerMap );
     mOverviewFrameMapComboBox->setExceptedItemList( QList< QgsComposerItem * >() << composerMap );
-    connect( mOverviewFrameMapComboBox, SIGNAL( itemChanged( QgsComposerItem * ) ), this, SLOT( overviewMapChanged( QgsComposerItem * ) ) );
+    connect( mOverviewFrameMapComboBox, &QgsComposerItemComboBox::itemChanged, this, &QgsComposerMapWidget::overviewMapChanged );
   }
 
   connect( mCrsSelector, &QgsProjectionSelectionWidget::crsChanged, this, &QgsComposerMapWidget::mapCrsChanged );
@@ -1655,7 +1655,7 @@ void QgsComposerMapWidget::on_mOverviewFrameStyleButton_clicked()
   symbolContext.setExpressionContext( &context );
   d->setContext( symbolContext );
 
-  connect( d, SIGNAL( widgetChanged() ), this, SLOT( updateOverviewFrameStyleFromWidget() ) );
+  connect( d, &QgsPanelWidget::widgetChanged, this, &QgsComposerMapWidget::updateOverviewFrameStyleFromWidget );
   connect( d, &QgsPanelWidget::panelAccepted, this, &QgsComposerMapWidget::cleanUpOverviewFrameStyleSelector );
   openPanel( d );
   mComposerMap->beginCommand( tr( "Overview frame style changed" ) );
diff --git a/src/app/composer/qgscomposerpicturewidget.cpp b/src/app/composer/qgscomposerpicturewidget.cpp
index d23d5864ccf..34b2086cc47 100644
--- a/src/app/composer/qgscomposerpicturewidget.cpp
+++ b/src/app/composer/qgscomposerpicturewidget.cpp
@@ -61,7 +61,7 @@ QgsComposerPictureWidget::QgsComposerPictureWidget( QgsComposerPicture *picture
   {
     mComposerMapComboBox->setComposition( mPicture->composition() );
     mComposerMapComboBox->setItemType( QgsComposerItem::ComposerMap );
-    connect( mComposerMapComboBox, SIGNAL( itemChanged( QgsComposerItem * ) ), this, SLOT( composerMapChanged( QgsComposerItem * ) ) );
+    connect( mComposerMapComboBox, &QgsComposerItemComboBox::itemChanged, this, &QgsComposerPictureWidget::composerMapChanged );
   }
 
   setGuiElementValues();
@@ -72,10 +72,10 @@ QgsComposerPictureWidget::QgsComposerPictureWidget( QgsComposerPicture *picture
   // mSearchDirectoriesGroupBox is a QgsCollapsibleGroupBoxBasic, so its collapsed state should not be saved/restored
   mSearchDirectoriesGroupBox->setCollapsed( true );
   // setup connection for loading previews on first expansion of group box
-  connect( mSearchDirectoriesGroupBox, SIGNAL( collapsedStateChanged( bool ) ), this, SLOT( loadPicturePreviews( bool ) ) );
+  connect( mSearchDirectoriesGroupBox, &QgsCollapsibleGroupBoxBasic::collapsedStateChanged, this, &QgsComposerPictureWidget::loadPicturePreviews );
 
-  connect( mPicture, SIGNAL( itemChanged() ), this, SLOT( setGuiElementValues() ) );
-  connect( mPicture, SIGNAL( pictureRotationChanged( double ) ), this, SLOT( setPicRotationSpinValue( double ) ) );
+  connect( mPicture, &QgsComposerObject::itemChanged, this, &QgsComposerPictureWidget::setGuiElementValues );
+  connect( mPicture, &QgsComposerPicture::pictureRotationChanged, this, &QgsComposerPictureWidget::setPicRotationSpinValue );
 
   //connections for data defined buttons
   connect( mSourceDDBtn, &QgsPropertyOverrideButton::activated, mPictureLineEdit, &QLineEdit::setDisabled );
diff --git a/src/app/composer/qgscomposerpolygonwidget.cpp b/src/app/composer/qgscomposerpolygonwidget.cpp
index 049812e56d0..d1393eec2d4 100644
--- a/src/app/composer/qgscomposerpolygonwidget.cpp
+++ b/src/app/composer/qgscomposerpolygonwidget.cpp
@@ -41,7 +41,7 @@ QgsComposerPolygonWidget::QgsComposerPolygonWidget( QgsComposerPolygon *composer
 
   if ( mComposerPolygon )
   {
-    connect( mComposerPolygon, SIGNAL( itemChanged() ), this, SLOT( setGuiElementValues() ) );
+    connect( mComposerPolygon, &QgsComposerObject::itemChanged, this, &QgsComposerPolygonWidget::setGuiElementValues );
   }
 }
 
@@ -67,7 +67,7 @@ void QgsComposerPolygonWidget::on_mPolygonStyleButton_clicked()
   symbolContext.setExpressionContext( &context );
   d->setContext( symbolContext );
 
-  connect( d, SIGNAL( widgetChanged() ), this, SLOT( updateStyleFromWidget() ) );
+  connect( d, &QgsPanelWidget::widgetChanged, this, &QgsComposerPolygonWidget::updateStyleFromWidget );
   connect( d, &QgsPanelWidget::panelAccepted, this, &QgsComposerPolygonWidget::cleanUpStyleSelector );
   openPanel( d );
   mComposerPolygon->beginCommand( tr( "Polygon style changed" ) );
diff --git a/src/app/composer/qgscomposerpolylinewidget.cpp b/src/app/composer/qgscomposerpolylinewidget.cpp
index 796336f7688..43f0f2bbf12 100644
--- a/src/app/composer/qgscomposerpolylinewidget.cpp
+++ b/src/app/composer/qgscomposerpolylinewidget.cpp
@@ -39,7 +39,7 @@ QgsComposerPolylineWidget::QgsComposerPolylineWidget( QgsComposerPolyline *compo
   updatePolylineStyle();
 
   if ( mComposerPolyline )
-    connect( mComposerPolyline, SIGNAL( itemChanged() ), this, SLOT( setGuiElementValues() ) );
+    connect( mComposerPolyline, &QgsComposerObject::itemChanged, this, &QgsComposerPolylineWidget::setGuiElementValues );
 }
 
 QgsComposerPolylineWidget::~QgsComposerPolylineWidget()
@@ -62,7 +62,7 @@ void QgsComposerPolylineWidget::on_mLineStyleButton_clicked()
   symbolContext.setExpressionContext( &context );
   d->setContext( symbolContext );
 
-  connect( d, SIGNAL( widgetChanged() ), this, SLOT( updateStyleFromWidget() ) );
+  connect( d, &QgsPanelWidget::widgetChanged, this, &QgsComposerPolylineWidget::updateStyleFromWidget );
   connect( d, &QgsPanelWidget::panelAccepted, this, &QgsComposerPolylineWidget::cleanUpStyleSelector );
   openPanel( d );
   mComposerPolyline->beginCommand( tr( "Polyline style changed" ) );
diff --git a/src/app/composer/qgscomposerscalebarwidget.cpp b/src/app/composer/qgscomposerscalebarwidget.cpp
index c3cc4fbf19d..0201c60972b 100644
--- a/src/app/composer/qgscomposerscalebarwidget.cpp
+++ b/src/app/composer/qgscomposerscalebarwidget.cpp
@@ -37,7 +37,7 @@ QgsComposerScaleBarWidget::QgsComposerScaleBarWidget( QgsComposerScaleBar *scale
 
   mSegmentSizeRadioGroup.addButton( mFixedSizeRadio );
   mSegmentSizeRadioGroup.addButton( mFitWidthRadio );
-  connect( &mSegmentSizeRadioGroup, SIGNAL( buttonClicked( QAbstractButton * ) ), this, SLOT( segmentSizeRadioChanged( QAbstractButton * ) ) );
+  connect( &mSegmentSizeRadioGroup, static_cast < void ( QButtonGroup::* )( QAbstractButton * ) > ( &QButtonGroup::buttonClicked ), this, &QgsComposerScaleBarWidget::segmentSizeRadioChanged );
 
   blockMemberSignals( true );
 
@@ -89,7 +89,7 @@ QgsComposerScaleBarWidget::QgsComposerScaleBarWidget( QgsComposerScaleBar *scale
     mMapItemComboBox->setItemType( QgsComposerItem::ComposerMap );
   }
 
-  connect( mMapItemComboBox, SIGNAL( itemChanged( QgsComposerItem * ) ), this, SLOT( composerMapChanged( QgsComposerItem * ) ) );
+  connect( mMapItemComboBox, &QgsComposerItemComboBox::itemChanged, this, &QgsComposerScaleBarWidget::composerMapChanged );
 
   registerDataDefinedButton( mFillColorDDBtn, QgsComposerObject::ScalebarFillColor );
   registerDataDefinedButton( mFillColor2DDBtn, QgsComposerObject::ScalebarFillColor2 );
@@ -567,7 +567,7 @@ void QgsComposerScaleBarWidget::connectUpdateSignal()
 {
   if ( mComposerScaleBar )
   {
-    QObject::connect( mComposerScaleBar, SIGNAL( itemChanged() ), this, SLOT( setGuiElements() ) );
+    connect( mComposerScaleBar, &QgsComposerObject::itemChanged, this, &QgsComposerScaleBarWidget::setGuiElements );
   }
 }
 
@@ -575,7 +575,7 @@ void QgsComposerScaleBarWidget::disconnectUpdateSignal()
 {
   if ( mComposerScaleBar )
   {
-    QObject::disconnect( mComposerScaleBar, SIGNAL( itemChanged() ), this, SLOT( setGuiElements() ) );
+    disconnect( mComposerScaleBar, &QgsComposerObject::itemChanged, this, &QgsComposerScaleBarWidget::setGuiElements );
   }
 }
 
diff --git a/src/app/composer/qgscomposershapewidget.cpp b/src/app/composer/qgscomposershapewidget.cpp
index ab90f8f82f7..c41874f0bbc 100644
--- a/src/app/composer/qgscomposershapewidget.cpp
+++ b/src/app/composer/qgscomposershapewidget.cpp
@@ -51,7 +51,7 @@ QgsComposerShapeWidget::QgsComposerShapeWidget( QgsComposerShape *composerShape
 
   if ( mComposerShape )
   {
-    connect( mComposerShape, SIGNAL( itemChanged() ), this, SLOT( setGuiElementValues() ) );
+    connect( mComposerShape, &QgsComposerObject::itemChanged, this, &QgsComposerShapeWidget::setGuiElementValues );
   }
 }
 
@@ -116,7 +116,7 @@ void QgsComposerShapeWidget::on_mShapeStyleButton_clicked()
   symbolContext.setExpressionContext( &context );
   d->setContext( symbolContext );
 
-  connect( d, SIGNAL( widgetChanged() ), this, SLOT( updateSymbolFromWidget() ) );
+  connect( d, &QgsPanelWidget::widgetChanged, this, &QgsComposerShapeWidget::updateSymbolFromWidget );
   connect( d, &QgsPanelWidget::panelAccepted, this, &QgsComposerShapeWidget::cleanUpSymbolSelector );
   openPanel( d );
   mComposerShape->beginCommand( tr( "Shape style changed" ) );
diff --git a/src/app/composer/qgscomposertablebackgroundcolorsdialog.cpp b/src/app/composer/qgscomposertablebackgroundcolorsdialog.cpp
index 1e3309d5560..e02143d71e0 100644
--- a/src/app/composer/qgscomposertablebackgroundcolorsdialog.cpp
+++ b/src/app/composer/qgscomposertablebackgroundcolorsdialog.cpp
@@ -49,7 +49,7 @@ QgsComposerTableBackgroundColorsDialog::QgsComposerTableBackgroundColorsDialog(
   mColorButtonMap.insert( QgsComposerTableV2::FirstRow, mFirstRowColorButton );
   mColorButtonMap.insert( QgsComposerTableV2::LastRow, mLastRowColorButton );
 
-  connect( buttonBox->button( QDialogButtonBox::Apply ), SIGNAL( clicked() ), this, SLOT( apply() ) );
+  connect( buttonBox->button( QDialogButtonBox::Apply ), &QAbstractButton::clicked, this, &QgsComposerTableBackgroundColorsDialog::apply );
 
   QgsSettings settings;
   restoreGeometry( settings.value( QStringLiteral( "Windows/ComposerTableBackgroundColorsDialog/geometry" ) ).toByteArray() );
diff --git a/src/app/composer/qgscompositionwidget.cpp b/src/app/composer/qgscompositionwidget.cpp
index 93a965d2a1a..47ba2e2e67c 100644
--- a/src/app/composer/qgscompositionwidget.cpp
+++ b/src/app/composer/qgscompositionwidget.cpp
@@ -24,6 +24,7 @@
 #include "qgssymbollayerutils.h"
 #include "qgsexpressioncontext.h"
 #include "qgsproject.h"
+#include "qgsvectorlayer.h"
 #include <QColorDialog>
 #include <QWidget>
 #include <QPrinter> //for screen resolution
@@ -50,7 +51,7 @@ QgsCompositionWidget::QgsCompositionWidget( QWidget *parent, QgsComposition *c )
   displayCompositionWidthHeight();
 
   updateVariables();
-  connect( mVariableEditor, SIGNAL( scopeChanged() ), this, SLOT( variablesChanged() ) );
+  connect( mVariableEditor, &QgsVariableEditorWidget::scopeChanged, this, &QgsCompositionWidget::variablesChanged );
   // listen out for variable edits
   connect( QgsApplication::instance(), &QgsApplication::customVariablesChanged, this, &QgsCompositionWidget::updateVariables );
   connect( QgsProject::instance(), &QgsProject::customVariablesChanged, this, &QgsCompositionWidget::updateVariables );
@@ -58,7 +59,7 @@ QgsCompositionWidget::QgsCompositionWidget( QWidget *parent, QgsComposition *c )
   if ( mComposition )
   {
     mNumPagesSpinBox->setValue( mComposition->numPages() );
-    connect( mComposition, SIGNAL( nPagesChanged() ), this, SLOT( setNumberPages() ) );
+    connect( mComposition, &QgsComposition::nPagesChanged, this, &QgsCompositionWidget::setNumberPages );
 
     updatePageStyle();
 
@@ -97,16 +98,16 @@ QgsCompositionWidget::QgsCompositionWidget( QWidget *parent, QgsComposition *c )
     if ( atlas )
     {
       // repopulate data defined buttons if atlas layer changes
-      connect( atlas, SIGNAL( coverageLayerChanged( QgsVectorLayer * ) ),
-               this, SLOT( populateDataDefinedButtons() ) );
-      connect( atlas, SIGNAL( toggled( bool ) ), this, SLOT( populateDataDefinedButtons() ) );
+      connect( atlas, &QgsAtlasComposition::coverageLayerChanged,
+               this, [ = ] { populateDataDefinedButtons(); } );
+      connect( atlas, &QgsAtlasComposition::toggled, this, &QgsCompositionWidget::populateDataDefinedButtons );
     }
   }
 
-  connect( mTopMarginSpinBox, SIGNAL( valueChanged( double ) ), this, SLOT( resizeMarginsChanged() ) );
-  connect( mRightMarginSpinBox, SIGNAL( valueChanged( double ) ), this, SLOT( resizeMarginsChanged() ) );
-  connect( mBottomMarginSpinBox, SIGNAL( valueChanged( double ) ), this, SLOT( resizeMarginsChanged() ) );
-  connect( mLeftMarginSpinBox, SIGNAL( valueChanged( double ) ), this, SLOT( resizeMarginsChanged() ) );
+  connect( mTopMarginSpinBox, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ), this, &QgsCompositionWidget::resizeMarginsChanged );
+  connect( mRightMarginSpinBox, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ), this, &QgsCompositionWidget::resizeMarginsChanged );
+  connect( mBottomMarginSpinBox, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ), this, &QgsCompositionWidget::resizeMarginsChanged );
+  connect( mLeftMarginSpinBox, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ), this, &QgsCompositionWidget::resizeMarginsChanged );
 
   connect( mPaperSizeDDBtn, &QgsPropertyOverrideButton::activated, mPaperSizeComboBox, &QComboBox::setDisabled );
   connect( mPaperWidthDDBtn, &QgsPropertyOverrideButton::activated, mPaperWidthDoubleSpinBox, &QgsDoubleSpinBox::setDisabled );
@@ -547,7 +548,7 @@ void QgsCompositionWidget::on_mPageStyleButton_clicked()
   symbolContext.setExpressionContext( &context );
   d->setContext( symbolContext );
 
-  connect( d, SIGNAL( widgetChanged() ), this, SLOT( updateStyleFromWidget() ) );
+  connect( d, &QgsPanelWidget::widgetChanged, this, &QgsCompositionWidget::updateStyleFromWidget );
   connect( d, &QgsPanelWidget::panelAccepted, this, &QgsCompositionWidget::cleanUpStyleSelector );
   openPanel( d );
 }
diff --git a/src/app/gps/qgsgpsinformationwidget.cpp b/src/app/gps/qgsgpsinformationwidget.cpp
index a5fb4861ba4..196f7ffa217 100644
--- a/src/app/gps/qgsgpsinformationwidget.cpp
+++ b/src/app/gps/qgsgpsinformationwidget.cpp
@@ -241,8 +241,8 @@ QgsGPSInformationWidget::QgsGPSInformationWidget( QgsMapCanvas *thepCanvas, QWid
   //SLM - added functionality
   mLogFile = nullptr;
 
-  connect( QgisApp::instance()->layerTreeView(), SIGNAL( currentLayerChanged( QgsMapLayer * ) ),
-           this, SLOT( updateCloseFeatureButton( QgsMapLayer * ) ) );
+  connect( QgisApp::instance()->layerTreeView(), &QgsLayerTreeView::currentLayerChanged,
+           this, &QgsGPSInformationWidget::updateCloseFeatureButton );
 
   mStackedWidget->setCurrentIndex( 3 ); // force to Options
   mBtnPosition->setFocus( Qt::TabFocusReason );
@@ -423,8 +423,8 @@ void QgsGPSInformationWidget::connectGps()
   showStatusBarMessage( tr( "Connecting to GPS device..." ) );
 
   QgsGPSDetector *detector = new QgsGPSDetector( port );
-  connect( detector, SIGNAL( detected( QgsGPSConnection * ) ), this, SLOT( connected( QgsGPSConnection * ) ) );
-  connect( detector, SIGNAL( detectionFailed() ), this, SLOT( timedout() ) );
+  connect( detector, static_cast < void ( QgsGPSDetector::* )( QgsGPSConnection * ) > ( &QgsGPSDetector::detected ), this, &QgsGPSInformationWidget::connected );
+  connect( detector, &QgsGPSDetector::detectionFailed, this, &QgsGPSInformationWidget::timedout );
   detector->advance();   // start the detection process
 }
 
@@ -439,8 +439,8 @@ void QgsGPSInformationWidget::timedout()
 void QgsGPSInformationWidget::connected( QgsGPSConnection *conn )
 {
   mNmea = conn;
-  connect( mNmea, SIGNAL( stateChanged( const QgsGPSInformation & ) ),
-           this, SLOT( displayGPSInformation( const QgsGPSInformation & ) ) );
+  connect( mNmea, &QgsGPSConnection::stateChanged,
+           this, &QgsGPSInformationWidget::displayGPSInformation );
   mGPSPlainTextEdit->appendPlainText( tr( "Connected!" ) );
   mConnectButton->setText( tr( "Dis&connect" ) );
   //insert connection into registry such that it can also be used by other dialogs or plugins
@@ -461,7 +461,7 @@ void QgsGPSInformationWidget::connected( QgsGPSConnection *conn )
       // crude way to separate chunks - use when manually editing file - NMEA parsers should discard
       mLogFileTextStream << "====" << "\r\n";
 
-      connect( mNmea, SIGNAL( nmeaSentenceReceived( const QString & ) ), this, SLOT( logNmeaSentence( const QString & ) ) ); // added to handle raw data
+      connect( mNmea, &QgsGPSConnection::nmeaSentenceReceived, this, &QgsGPSInformationWidget::logNmeaSentence ); // added to handle raw data
     }
     else  // error opening file
     {
@@ -478,7 +478,7 @@ void QgsGPSInformationWidget::disconnectGps()
 {
   if ( mLogFile && mLogFile->isOpen() )
   {
-    disconnect( mNmea, SIGNAL( nmeaSentenceReceived( const QString & ) ), this, SLOT( logNmeaSentence( const QString & ) ) );
+    disconnect( mNmea, &QgsGPSConnection::nmeaSentenceReceived, this, &QgsGPSInformationWidget::logNmeaSentence );
     mLogFile->close();
     delete mLogFile;
     mLogFile = nullptr;
@@ -980,8 +980,8 @@ void QgsGPSInformationWidget::on_mBtnCloseFeature_clicked()
 
 void QgsGPSInformationWidget::connectGpsSlot()
 {
-  connect( mNmea, SIGNAL( stateChanged( const QgsGPSInformation & ) ),
-           this, SLOT( displayGPSInformation( const QgsGPSInformation & ) ) );
+  connect( mNmea, &QgsGPSConnection::stateChanged,
+           this, &QgsGPSInformationWidget::displayGPSInformation );
 }
 
 void QgsGPSInformationWidget::on_mBtnRefreshDevices_clicked()
@@ -1065,17 +1065,17 @@ void QgsGPSInformationWidget::updateCloseFeatureButton( QgsMapLayer *lyr )
   {
     if ( mpLastLayer )  // disconnect previous layer
     {
-      disconnect( mpLastLayer, SIGNAL( editingStarted() ),
-                  this, SLOT( layerEditStateChanged() ) );
-      disconnect( mpLastLayer, SIGNAL( editingStopped() ),
-                  this, SLOT( layerEditStateChanged() ) );
+      disconnect( mpLastLayer, &QgsVectorLayer::editingStarted,
+                  this, &QgsGPSInformationWidget::layerEditStateChanged );
+      disconnect( mpLastLayer, &QgsVectorLayer::editingStopped,
+                  this, &QgsGPSInformationWidget::layerEditStateChanged );
     }
     if ( vlayer ) // connect new layer
     {
-      connect( vlayer, SIGNAL( editingStarted() ),
-               this, SLOT( layerEditStateChanged() ) );
-      connect( vlayer, SIGNAL( editingStopped() ),
-               this, SLOT( layerEditStateChanged() ) );
+      connect( vlayer, &QgsVectorLayer::editingStarted,
+               this, &QgsGPSInformationWidget::layerEditStateChanged );
+      connect( vlayer, &QgsVectorLayer::editingStopped,
+               this, &QgsGPSInformationWidget::layerEditStateChanged );
     }
     mpLastLayer = vlayer;
   }
diff --git a/src/app/nodetool/qgsmaptoolnodetool.cpp b/src/app/nodetool/qgsmaptoolnodetool.cpp
index b0282484bdd..cb70fa7d448 100644
--- a/src/app/nodetool/qgsmaptoolnodetool.cpp
+++ b/src/app/nodetool/qgsmaptoolnodetool.cpp
@@ -250,14 +250,14 @@ void QgsMapToolNodeTool::canvasPressEvent( QgsMapMouseEvent *e )
       mSelectedFeature = new QgsSelectedFeature( snapResults[0].snappedAtGeometry, vlayer, mCanvas );
       updateSelectFeature();
     }
-    connect( QgisApp::instance()->layerTreeView(), SIGNAL( currentLayerChanged( QgsMapLayer * ) ), this, SLOT( currentLayerChanged( QgsMapLayer * ) ) );
-    connect( mSelectedFeature, SIGNAL( destroyed() ), this, SLOT( selectedFeatureDestroyed() ) );
-    connect( vlayer, SIGNAL( geometryChanged( QgsFeatureId, const QgsGeometry & ) ), this, SLOT( geometryChanged( QgsFeatureId, const QgsGeometry & ) ) );
-    connect( vlayer, SIGNAL( editingStopped() ), this, SLOT( editingToggled() ) );
+    connect( QgisApp::instance()->layerTreeView(), &QgsLayerTreeView::currentLayerChanged, this, &QgsMapToolNodeTool::currentLayerChanged );
+    connect( mSelectedFeature, &QObject::destroyed, this, &QgsMapToolNodeTool::selectedFeatureDestroyed );
+    connect( vlayer, &QgsVectorLayer::geometryChanged, this, &QgsMapToolNodeTool::geometryChanged );
+    connect( vlayer, &QgsVectorLayer::editingStopped, this, &QgsMapToolNodeTool::editingToggled );
     mIsPoint = vlayer->geometryType() == QgsWkbTypes::PointGeometry;
     mNodeEditor = new QgsNodeEditor( vlayer, mSelectedFeature, mCanvas );
     QgisApp::instance()->addDockWidget( Qt::LeftDockWidgetArea, mNodeEditor );
-    connect( mNodeEditor, SIGNAL( deleteSelectedRequested() ), this, SLOT( deleteNodeSelection() ) );
+    connect( mNodeEditor, &QgsNodeEditor::deleteSelectedRequested, this, &QgsMapToolNodeTool::deleteNodeSelection );
   }
   else
   {
@@ -581,9 +581,9 @@ void QgsMapToolNodeTool::cleanTool( bool deleteSelectedFeature )
     QgsVectorLayer *vlayer = mSelectedFeature->vlayer();
     Q_ASSERT( vlayer );
 
-    disconnect( QgisApp::instance()->layerTreeView(), SIGNAL( currentLayerChanged( QgsMapLayer * ) ), this, SLOT( currentLayerChanged( QgsMapLayer * ) ) );
-    disconnect( mSelectedFeature, SIGNAL( destroyed() ), this, SLOT( selectedFeatureDestroyed() ) );
-    disconnect( vlayer, SIGNAL( editingStopped() ), this, SLOT( editingToggled() ) );
+    disconnect( QgisApp::instance()->layerTreeView(), &QgsLayerTreeView::currentLayerChanged, this, &QgsMapToolNodeTool::currentLayerChanged );
+    disconnect( mSelectedFeature, &QObject::destroyed, this, &QgsMapToolNodeTool::selectedFeatureDestroyed );
+    disconnect( vlayer, &QgsVectorLayer::editingStopped, this, &QgsMapToolNodeTool::editingToggled );
 
     if ( deleteSelectedFeature )
       delete mSelectedFeature;
diff --git a/src/app/nodetool/qgsnodeeditor.cpp b/src/app/nodetool/qgsnodeeditor.cpp
index 4b28cd96702..ff39e3977c3 100644
--- a/src/app/nodetool/qgsnodeeditor.cpp
+++ b/src/app/nodetool/qgsnodeeditor.cpp
@@ -68,7 +68,7 @@ QgsNodeEditorModel::QgsNodeEditorModel( QgsVectorLayer *layer, QgsSelectedFeatur
     mWidgetFont = parentWidget->font();
   }
 
-  connect( mSelectedFeature, SIGNAL( vertexMapChanged() ), this, SLOT( featureChanged() ) );
+  connect( mSelectedFeature, &QgsSelectedFeature::vertexMapChanged, this, &QgsNodeEditorModel::featureChanged );
 }
 
 int QgsNodeEditorModel::rowCount( const QModelIndex &parent ) const
@@ -306,8 +306,8 @@ QgsNodeEditor::QgsNodeEditor(
 
   setWidget( mTableView );
 
-  connect( mSelectedFeature, SIGNAL( selectionChanged() ), this, SLOT( updateTableSelection() ) );
-  connect( mTableView->selectionModel(), SIGNAL( selectionChanged( QItemSelection, QItemSelection ) ), this, SLOT( updateNodeSelection( QItemSelection, QItemSelection ) ) );
+  connect( mSelectedFeature, &QgsSelectedFeature::selectionChanged, this, &QgsNodeEditor::updateTableSelection );
+  connect( mTableView->selectionModel(), &QItemSelectionModel::selectionChanged, this, &QgsNodeEditor::updateNodeSelection );
 }
 
 void QgsNodeEditor::updateTableSelection()
diff --git a/src/app/nodetool/qgsselectedfeature.cpp b/src/app/nodetool/qgsselectedfeature.cpp
index 074f0c22daf..abc6f2783c6 100644
--- a/src/app/nodetool/qgsselectedfeature.cpp
+++ b/src/app/nodetool/qgsselectedfeature.cpp
@@ -94,27 +94,27 @@ void QgsSelectedFeature::setSelectedFeature( QgsFeatureId featureId, QgsVectorLa
   mGeometry = nullptr;
 
   // signal changing of current layer
-  connect( QgisApp::instance()->layerTreeView(), SIGNAL( currentLayerChanged( QgsMapLayer * ) ), this, SLOT( currentLayerChanged( QgsMapLayer * ) ) );
+  connect( QgisApp::instance()->layerTreeView(), &QgsLayerTreeView::currentLayerChanged, this, &QgsSelectedFeature::currentLayerChanged );
 
   // feature was deleted
-  connect( mVlayer, SIGNAL( featureDeleted( QgsFeatureId ) ), this, SLOT( featureDeleted( QgsFeatureId ) ) );
+  connect( mVlayer, &QgsVectorLayer::featureDeleted, this, &QgsSelectedFeature::featureDeleted );
 
   // rolling back
-  connect( mVlayer, SIGNAL( beforeRollBack() ), this, SLOT( beforeRollBack() ) );
+  connect( mVlayer, &QgsVectorLayer::beforeRollBack, this, &QgsSelectedFeature::beforeRollBack );
 
   // projection or extents changed
-  connect( canvas, SIGNAL( destinationCrsChanged() ), this, SLOT( updateVertexMarkersPosition() ) );
-  connect( canvas, SIGNAL( extentsChanged() ), this, SLOT( updateVertexMarkersPosition() ) );
+  connect( canvas, &QgsMapCanvas::destinationCrsChanged, this, &QgsSelectedFeature::updateVertexMarkersPosition );
+  connect( canvas, &QgsMapCanvas::extentsChanged, this, &QgsSelectedFeature::updateVertexMarkersPosition );
 
   // geometry was changed
-  connect( mVlayer, SIGNAL( geometryChanged( QgsFeatureId, const QgsGeometry & ) ), this, SLOT( geometryChanged( QgsFeatureId, const QgsGeometry & ) ) );
+  connect( mVlayer, &QgsVectorLayer::geometryChanged, this, &QgsSelectedFeature::geometryChanged );
 
   replaceVertexMap();
 }
 
 void QgsSelectedFeature::beforeRollBack()
 {
-  disconnect( mVlayer, SIGNAL( geometryChanged( QgsFeatureId, const QgsGeometry & ) ), this, SLOT( geometryChanged( QgsFeatureId, const QgsGeometry & ) ) );
+  disconnect( mVlayer, &QgsVectorLayer::geometryChanged, this, &QgsSelectedFeature::geometryChanged );
   deleteVertexMap();
 }
 
@@ -123,7 +123,7 @@ void QgsSelectedFeature::beginGeometryChange()
   Q_ASSERT( !mChangingGeometry );
   mChangingGeometry = true;
 
-  disconnect( mVlayer, SIGNAL( geometryChanged( QgsFeatureId, const QgsGeometry & ) ), this, SLOT( geometryChanged( QgsFeatureId, const QgsGeometry & ) ) );
+  disconnect( mVlayer, &QgsVectorLayer::geometryChanged, this, &QgsSelectedFeature::geometryChanged );
 }
 
 void QgsSelectedFeature::endGeometryChange()
@@ -131,7 +131,7 @@ void QgsSelectedFeature::endGeometryChange()
   Q_ASSERT( mChangingGeometry );
   mChangingGeometry = false;
 
-  connect( mVlayer, SIGNAL( geometryChanged( QgsFeatureId, const QgsGeometry & ) ), this, SLOT( geometryChanged( QgsFeatureId, const QgsGeometry & ) ) );
+  connect( mVlayer, &QgsVectorLayer::geometryChanged, this, &QgsSelectedFeature::geometryChanged );
 }
 
 void QgsSelectedFeature::canvasLayersChanged()
@@ -185,8 +185,8 @@ void QgsSelectedFeature::validateGeometry( QgsGeometry *g )
   }
 
   mValidator = new QgsGeometryValidator( g );
-  connect( mValidator, SIGNAL( errorFound( QgsGeometry::Error ) ), this, SLOT( addError( QgsGeometry::Error ) ) );
-  connect( mValidator, SIGNAL( finished() ), this, SLOT( validationFinished() ) );
+  connect( mValidator, &QgsGeometryValidator::errorFound, this, &QgsSelectedFeature::addError );
+  connect( mValidator, &QThread::finished, this, &QgsSelectedFeature::validationFinished );
   mValidator->start();
 
   QStatusBar *sb = QgisApp::instance()->statusBar();
diff --git a/src/app/openstreetmap/qgsosmdownloaddialog.cpp b/src/app/openstreetmap/qgsosmdownloaddialog.cpp
index 7ec1ffd1f64..6d438ed521b 100644
--- a/src/app/openstreetmap/qgsosmdownloaddialog.cpp
+++ b/src/app/openstreetmap/qgsosmdownloaddialog.cpp
@@ -44,16 +44,16 @@ QgsOSMDownloadDialog::QgsOSMDownloadDialog( QWidget *parent )
   populateLayers();
   onExtentCanvas();
 
-  connect( radExtentCanvas, SIGNAL( clicked() ), this, SLOT( onExtentCanvas() ) );
-  connect( radExtentLayer, SIGNAL( clicked() ), this, SLOT( onExtentLayer() ) );
-  connect( radExtentManual, SIGNAL( clicked() ), this, SLOT( onExtentManual() ) );
-  connect( cboLayers, SIGNAL( currentIndexChanged( int ) ), this, SLOT( onCurrentLayerChanged( int ) ) );
-  connect( btnBrowse, SIGNAL( clicked() ), this, SLOT( onBrowseClicked() ) );
-  connect( buttonBox, SIGNAL( accepted() ), this, SLOT( onOK() ) );
-  connect( buttonBox, SIGNAL( rejected() ), this, SLOT( onClose() ) );
+  connect( radExtentCanvas, &QAbstractButton::clicked, this, &QgsOSMDownloadDialog::onExtentCanvas );
+  connect( radExtentLayer, &QAbstractButton::clicked, this, &QgsOSMDownloadDialog::onExtentLayer );
+  connect( radExtentManual, &QAbstractButton::clicked, this, &QgsOSMDownloadDialog::onExtentManual );
+  connect( cboLayers, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsOSMDownloadDialog::onCurrentLayerChanged );
+  connect( btnBrowse, &QAbstractButton::clicked, this, &QgsOSMDownloadDialog::onBrowseClicked );
+  connect( buttonBox, &QDialogButtonBox::accepted, this, &QgsOSMDownloadDialog::onOK );
+  connect( buttonBox, &QDialogButtonBox::rejected, this, &QgsOSMDownloadDialog::onClose );
 
-  connect( mDownload, SIGNAL( finished() ), this, SLOT( onFinished() ) );
-  connect( mDownload, SIGNAL( downloadProgress( qint64, qint64 ) ), this, SLOT( onDownloadProgress( qint64, qint64 ) ) );
+  connect( mDownload, &QgsOSMDownload::finished, this, &QgsOSMDownloadDialog::onFinished );
+  connect( mDownload, &QgsOSMDownload::downloadProgress, this, &QgsOSMDownloadDialog::onDownloadProgress );
 }
 
 QgsOSMDownloadDialog::~QgsOSMDownloadDialog()
diff --git a/src/app/openstreetmap/qgsosmexportdialog.cpp b/src/app/openstreetmap/qgsosmexportdialog.cpp
index 748b262b0d2..74fa3d4a16d 100644
--- a/src/app/openstreetmap/qgsosmexportdialog.cpp
+++ b/src/app/openstreetmap/qgsosmexportdialog.cpp
@@ -33,16 +33,16 @@ QgsOSMExportDialog::QgsOSMExportDialog( QWidget *parent )
 {
   setupUi( this );
 
-  connect( btnBrowseDb, SIGNAL( clicked() ), this, SLOT( onBrowse() ) );
-  connect( buttonBox, SIGNAL( accepted() ), this, SLOT( onOK() ) );
-  connect( buttonBox, SIGNAL( rejected() ), this, SLOT( onClose() ) );
-  connect( editDbFileName, SIGNAL( textChanged( QString ) ), this, SLOT( updateLayerName() ) );
-  connect( radPoints, SIGNAL( clicked() ), this, SLOT( updateLayerName() ) );
-  connect( radPolylines, SIGNAL( clicked() ), this, SLOT( updateLayerName() ) );
-  connect( radPolygons, SIGNAL( clicked() ), this, SLOT( updateLayerName() ) );
-  connect( btnLoadTags, SIGNAL( clicked() ), this, SLOT( onLoadTags() ) );
-  connect( btnSelectAll, SIGNAL( clicked() ), this, SLOT( onSelectAll() ) );
-  connect( btnDeselectAll, SIGNAL( clicked() ), this, SLOT( onDeselectAll() ) );
+  connect( btnBrowseDb, &QAbstractButton::clicked, this, &QgsOSMExportDialog::onBrowse );
+  connect( buttonBox, &QDialogButtonBox::accepted, this, &QgsOSMExportDialog::onOK );
+  connect( buttonBox, &QDialogButtonBox::rejected, this, &QgsOSMExportDialog::onClose );
+  connect( editDbFileName, &QLineEdit::textChanged, this, &QgsOSMExportDialog::updateLayerName );
+  connect( radPoints, &QAbstractButton::clicked, this, &QgsOSMExportDialog::updateLayerName );
+  connect( radPolylines, &QAbstractButton::clicked, this, &QgsOSMExportDialog::updateLayerName );
+  connect( radPolygons, &QAbstractButton::clicked, this, &QgsOSMExportDialog::updateLayerName );
+  connect( btnLoadTags, &QAbstractButton::clicked, this, &QgsOSMExportDialog::onLoadTags );
+  connect( btnSelectAll, &QAbstractButton::clicked, this, &QgsOSMExportDialog::onSelectAll );
+  connect( btnDeselectAll, &QAbstractButton::clicked, this, &QgsOSMExportDialog::onDeselectAll );
 
   mTagsModel = new QStandardItemModel( this );
   mTagsModel->setHorizontalHeaderLabels( QStringList() << tr( "Tag" ) << tr( "Count" ) << tr( "Not null" ) );
diff --git a/src/app/openstreetmap/qgsosmimportdialog.cpp b/src/app/openstreetmap/qgsosmimportdialog.cpp
index 9733f02cf67..cbf18f19877 100644
--- a/src/app/openstreetmap/qgsosmimportdialog.cpp
+++ b/src/app/openstreetmap/qgsosmimportdialog.cpp
@@ -28,14 +28,14 @@ QgsOSMImportDialog::QgsOSMImportDialog( QWidget *parent )
 {
   setupUi( this );
 
-  connect( btnBrowseXml, SIGNAL( clicked() ), this, SLOT( onBrowseXml() ) );
-  connect( btnBrowseDb, SIGNAL( clicked() ), this, SLOT( onBrowseDb() ) );
-  connect( editXmlFileName, SIGNAL( textChanged( const QString & ) ), this, SLOT( xmlFileNameChanged( const QString & ) ) );
-  connect( editDbFileName, SIGNAL( textChanged( const QString & ) ), this, SLOT( dbFileNameChanged( const QString & ) ) );
-  connect( buttonBox, SIGNAL( accepted() ), this, SLOT( onOK() ) );
-  connect( buttonBox, SIGNAL( rejected() ), this, SLOT( onClose() ) );
+  connect( btnBrowseXml, &QAbstractButton::clicked, this, &QgsOSMImportDialog::onBrowseXml );
+  connect( btnBrowseDb, &QAbstractButton::clicked, this, &QgsOSMImportDialog::onBrowseDb );
+  connect( editXmlFileName, &QLineEdit::textChanged, this, &QgsOSMImportDialog::xmlFileNameChanged );
+  connect( editDbFileName, &QLineEdit::textChanged, this, &QgsOSMImportDialog::dbFileNameChanged );
+  connect( buttonBox, &QDialogButtonBox::accepted, this, &QgsOSMImportDialog::onOK );
+  connect( buttonBox, &QDialogButtonBox::rejected, this, &QgsOSMImportDialog::onClose );
 
-  connect( mImport, SIGNAL( progress( int ) ), this, SLOT( onProgress( int ) ) );
+  connect( mImport, &QgsOSMXmlImport::progress, this, &QgsOSMImportDialog::onProgress );
 }
 
 QgsOSMImportDialog::~QgsOSMImportDialog()
diff --git a/src/app/pluginmanager/qgspluginmanager.cpp b/src/app/pluginmanager/qgspluginmanager.cpp
index a3821eb8102..70111d13da5 100644
--- a/src/app/pluginmanager/qgspluginmanager.cpp
+++ b/src/app/pluginmanager/qgspluginmanager.cpp
@@ -106,9 +106,9 @@ QgsPluginManager::QgsPluginManager( QWidget *parent, bool pluginsAreEnabled, Qt:
   mOptionsListWidget->setCurrentRow( 0 );
 
   // Connect other signals
-  connect( mOptionsListWidget, SIGNAL( currentRowChanged( int ) ), this, SLOT( setCurrentTab( int ) ) );
-  connect( vwPlugins->selectionModel(), SIGNAL( currentChanged( const QModelIndex &, const QModelIndex & ) ), this, SLOT( currentPluginChanged( const QModelIndex & ) ) );
-  connect( mModelPlugins, SIGNAL( itemChanged( QStandardItem * ) ), this, SLOT( pluginItemChanged( QStandardItem * ) ) );
+  connect( mOptionsListWidget, &QListWidget::currentRowChanged, this, &QgsPluginManager::setCurrentTab );
+  connect( vwPlugins->selectionModel(), &QItemSelectionModel::currentChanged, this, &QgsPluginManager::currentPluginChanged );
+  connect( mModelPlugins, &QStandardItemModel::itemChanged, this, &QgsPluginManager::pluginItemChanged );
   // Force setting the status filter (if the active tab was 0, the setCurrentRow( 0 ) above doesn't take any action)
   setCurrentTab( 0 );
 
@@ -180,10 +180,10 @@ void QgsPluginManager::setPythonUtils( QgsPythonUtils *pythonUtils )
   vwPlugins->addAction( actionSortByVote );
   vwPlugins->addAction( actionSortByStatus );
   vwPlugins->setContextMenuPolicy( Qt::ActionsContextMenu );
-  connect( actionSortByName, SIGNAL( triggered() ), mModelProxy, SLOT( sortPluginsByName() ) );
-  connect( actionSortByDownloads, SIGNAL( triggered() ), mModelProxy, SLOT( sortPluginsByDownloads() ) );
-  connect( actionSortByVote, SIGNAL( triggered() ), mModelProxy, SLOT( sortPluginsByVote() ) );
-  connect( actionSortByStatus, SIGNAL( triggered() ), mModelProxy, SLOT( sortPluginsByStatus() ) );
+  connect( actionSortByName, &QAction::triggered, mModelProxy, &QgsPluginSortFilterProxyModel::sortPluginsByName );
+  connect( actionSortByDownloads, &QAction::triggered, mModelProxy, &QgsPluginSortFilterProxyModel::sortPluginsByDownloads );
+  connect( actionSortByVote, &QAction::triggered, mModelProxy, &QgsPluginSortFilterProxyModel::sortPluginsByVote );
+  connect( actionSortByStatus, &QAction::triggered, mModelProxy, &QgsPluginSortFilterProxyModel::sortPluginsByStatus );
 
   // get the QgsSettings group from the installer
   QString settingsGroup;
@@ -1010,12 +1010,12 @@ void QgsPluginManager::addToRepositoryList( const QMap<QString, QString> &reposi
     buttonRefreshRepos->setText( tr( "Reload all repositories" ) );
     QAction *actionEnableThisRepositoryOnly = new QAction( tr( "Only show plugins from selected repository" ), treeRepositories );
     treeRepositories->addAction( actionEnableThisRepositoryOnly );
-    connect( actionEnableThisRepositoryOnly, SIGNAL( triggered() ), this, SLOT( setRepositoryFilter() ) );
+    connect( actionEnableThisRepositoryOnly, &QAction::triggered, this, &QgsPluginManager::setRepositoryFilter );
     treeRepositories->setContextMenuPolicy( Qt::ActionsContextMenu );
     QAction *actionClearFilter = new QAction( tr( "Clear filter" ), treeRepositories );
     actionClearFilter->setEnabled( repository.value( QStringLiteral( "inspection_filter" ) ) == QLatin1String( "true" ) );
     treeRepositories->addAction( actionClearFilter );
-    connect( actionClearFilter, SIGNAL( triggered() ), this, SLOT( clearRepositoryFilter() ) );
+    connect( actionClearFilter, &QAction::triggered, this, &QgsPluginManager::clearRepositoryFilter );
   }
 
   QString key = repository.value( QStringLiteral( "name" ) );
diff --git a/src/app/qgisappinterface.cpp b/src/app/qgisappinterface.cpp
index 8c423e3a8ef..66023c3f222 100644
--- a/src/app/qgisappinterface.cpp
+++ b/src/app/qgisappinterface.cpp
@@ -51,21 +51,21 @@ QgisAppInterface::QgisAppInterface( QgisApp *_qgis )
   , pluginManagerIface( _qgis->pluginManager() )
 {
   // connect signals
-  connect( qgis->layerTreeView(), SIGNAL( currentLayerChanged( QgsMapLayer * ) ),
-           this, SIGNAL( currentLayerChanged( QgsMapLayer * ) ) );
-  connect( qgis, SIGNAL( currentThemeChanged( QString ) ),
-           this, SIGNAL( currentThemeChanged( QString ) ) );
+  connect( qgis->layerTreeView(), &QgsLayerTreeView::currentLayerChanged,
+           this, &QgisInterface::currentLayerChanged );
+  connect( qgis, &QgisApp::currentThemeChanged,
+           this, &QgisAppInterface::currentThemeChanged );
   connect( qgis, &QgisApp::composerOpened, this, &QgisAppInterface::composerOpened );
   connect( qgis, &QgisApp::composerWillBeClosed, this, &QgisAppInterface::composerWillBeClosed );
   connect( qgis, &QgisApp::composerClosed, this, &QgisAppInterface::composerClosed );
-  connect( qgis, SIGNAL( initializationCompleted() ),
-           this, SIGNAL( initializationCompleted() ) );
-  connect( qgis, SIGNAL( newProject() ),
-           this, SIGNAL( newProjectCreated() ) );
-  connect( qgis, SIGNAL( projectRead() ),
-           this, SIGNAL( projectRead() ) );
-  connect( qgis, SIGNAL( layerSavedAs( QgsMapLayer *, QString ) ),
-           this, SIGNAL( layerSavedAs( QgsMapLayer *, QString ) ) );
+  connect( qgis, &QgisApp::initializationCompleted,
+           this, &QgisInterface::initializationCompleted );
+  connect( qgis, &QgisApp::newProject,
+           this, &QgisInterface::newProjectCreated );
+  connect( qgis, &QgisApp::projectRead,
+           this, &QgisInterface::projectRead );
+  connect( qgis, &QgisApp::layerSavedAs,
+           this, &QgisInterface::layerSavedAs );
 }
 
 QgsPluginManagerInterface *QgisAppInterface::pluginManagerInterface()
diff --git a/src/app/qgsabout.cpp b/src/app/qgsabout.cpp
index 507bbabdedf..13527481ea6 100644
--- a/src/app/qgsabout.cpp
+++ b/src/app/qgsabout.cpp
@@ -65,7 +65,7 @@ void QgsAbout::init()
   developersMapView->page()->setLinkDelegationPolicy( QWebPage::DelegateAllLinks );
   developersMapView->setContextMenuPolicy( Qt::NoContextMenu );
 
-  connect( developersMapView, SIGNAL( linkClicked( const QUrl & ) ), this, SLOT( openUrl( const QUrl & ) ) );
+  connect( developersMapView, &QWebView::linkClicked, this, &QgsAbout::openUrl );
 
   // set the 60x60 icon pixmap
   qgisIcon->setPixmap( QPixmap( QgsApplication::appIconPath() ) );
diff --git a/src/app/qgsaddtaborgroup.cpp b/src/app/qgsaddtaborgroup.cpp
index bbe3d08b512..ebaae7c85bd 100644
--- a/src/app/qgsaddtaborgroup.cpp
+++ b/src/app/qgsaddtaborgroup.cpp
@@ -49,8 +49,8 @@ QgsAddTabOrGroup::QgsAddTabOrGroup( QgsVectorLayer *lyr, const QList < TabPair >
     mGroupButton->setEnabled( false );
   }
 
-  connect( mTabButton, SIGNAL( toggled( bool ) ), this, SLOT( on_mTabButton_toggled( bool ) ) );
-  connect( mGroupButton, SIGNAL( toggled( bool ) ), this, SLOT( on_mGroupButton_toggled( bool ) ) );
+  connect( mTabButton, &QAbstractButton::toggled, this, &QgsAddTabOrGroup::on_mTabButton_toggled );
+  connect( mGroupButton, &QAbstractButton::toggled, this, &QgsAddTabOrGroup::on_mGroupButton_toggled );
 
   mColumnCountSpinBox->setValue( QgsSettings().value( QStringLiteral( "/qgis/attributeForm/defaultTabColumnCount" ), 1 ).toInt() );
 
diff --git a/src/app/qgsalignrasterdialog.cpp b/src/app/qgsalignrasterdialog.cpp
index 6bb27c13ab8..fd0eb2b95d1 100644
--- a/src/app/qgsalignrasterdialog.cpp
+++ b/src/app/qgsalignrasterdialog.cpp
@@ -83,31 +83,31 @@ QgsAlignRasterDialog::QgsAlignRasterDialog( QWidget *parent )
   mAlign = new QgsAlignRaster;
   mAlign->setProgressHandler( new QgsAlignRasterDialogProgress( mProgress ) );
 
-  connect( mBtnAdd, SIGNAL( clicked( bool ) ), this, SLOT( addLayer() ) );
-  connect( mBtnRemove, SIGNAL( clicked( bool ) ), this, SLOT( removeLayer() ) );
-  connect( mBtnEdit, SIGNAL( clicked( bool ) ), this, SLOT( editLayer() ) );
+  connect( mBtnAdd, &QAbstractButton::clicked, this, &QgsAlignRasterDialog::addLayer );
+  connect( mBtnRemove, &QAbstractButton::clicked, this, &QgsAlignRasterDialog::removeLayer );
+  connect( mBtnEdit, &QAbstractButton::clicked, this, &QgsAlignRasterDialog::editLayer );
 
-  connect( mCboReferenceLayer, SIGNAL( currentIndexChanged( int ) ), this, SLOT( referenceLayerChanged() ) );
-  connect( mCrsSelector, SIGNAL( crsChanged( QgsCoordinateReferenceSystem ) ), this, SLOT( destinationCrsChanged() ) );
-  connect( mSpinCellSizeX, SIGNAL( valueChanged( double ) ), this, SLOT( updateParametersFromReferenceLayer() ) );
-  connect( mSpinCellSizeY, SIGNAL( valueChanged( double ) ), this, SLOT( updateParametersFromReferenceLayer() ) );
-  connect( mSpinGridOffsetX, SIGNAL( valueChanged( double ) ), this, SLOT( updateParametersFromReferenceLayer() ) );
-  connect( mSpinGridOffsetY, SIGNAL( valueChanged( double ) ), this, SLOT( updateParametersFromReferenceLayer() ) );
+  connect( mCboReferenceLayer, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, [ = ] { referenceLayerChanged(); } );
+  connect( mCrsSelector, &QgsProjectionSelectionWidget::crsChanged, this, &QgsAlignRasterDialog::destinationCrsChanged );
+  connect( mSpinCellSizeX, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ), this, &QgsAlignRasterDialog::updateParametersFromReferenceLayer );
+  connect( mSpinCellSizeY, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ), this, &QgsAlignRasterDialog::updateParametersFromReferenceLayer );
+  connect( mSpinGridOffsetX, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ), this, &QgsAlignRasterDialog::updateParametersFromReferenceLayer );
+  connect( mSpinGridOffsetY, static_cast < void ( QDoubleSpinBox::* )( double ) > ( &QDoubleSpinBox::valueChanged ), this, &QgsAlignRasterDialog::updateParametersFromReferenceLayer );
 
-  connect( mChkCustomCRS, SIGNAL( clicked( bool ) ), this, SLOT( updateCustomCrs() ) );
-  connect( mChkCustomCellSize, SIGNAL( clicked( bool ) ), this, SLOT( updateCustomCellSize() ) );
-  connect( mChkCustomGridOffset, SIGNAL( clicked( bool ) ), this, SLOT( updateCustomGridOffset() ) );
+  connect( mChkCustomCRS, &QAbstractButton::clicked, this, &QgsAlignRasterDialog::updateCustomCrs );
+  connect( mChkCustomCellSize, &QAbstractButton::clicked, this, &QgsAlignRasterDialog::updateCustomCellSize );
+  connect( mChkCustomGridOffset, &QAbstractButton::clicked, this, &QgsAlignRasterDialog::updateCustomGridOffset );
 
   mClipExtentGroupBox->setChecked( false );
   mClipExtentGroupBox->setCollapsed( true );
   mClipExtentGroupBox->setTitleBase( tr( "Clip to Extent" ) );
   QgsMapCanvas *mc = QgisApp::instance()->mapCanvas();
   mClipExtentGroupBox->setCurrentExtent( mc->extent(), mc->mapSettings().destinationCrs() );
-  connect( mClipExtentGroupBox, SIGNAL( extentChanged( QgsRectangle ) ), this, SLOT( clipExtentChanged() ) );
+  connect( mClipExtentGroupBox, &QgsExtentGroupBox::extentChanged, this, &QgsAlignRasterDialog::clipExtentChanged );
 
   // TODO: auto-detect reference layer
 
-  connect( buttonBox, SIGNAL( accepted() ), this, SLOT( runAlign() ) );
+  connect( buttonBox, &QDialogButtonBox::accepted, this, &QgsAlignRasterDialog::runAlign );
 
   populateLayersView();
 
@@ -402,7 +402,7 @@ QgsAlignRasterLayerConfigDialog::QgsAlignRasterLayerConfigDialog()
 
   editOutput = new QLineEdit( this );
   btnBrowse = new QPushButton( tr( "Browse..." ), this );
-  connect( btnBrowse, SIGNAL( clicked( bool ) ), this, SLOT( browseOutputFilename() ) );
+  connect( btnBrowse, &QAbstractButton::clicked, this, &QgsAlignRasterLayerConfigDialog::browseOutputFilename );
 
   QHBoxLayout *layoutOutput = new QHBoxLayout();
   layoutOutput->addWidget( editOutput );
@@ -411,8 +411,8 @@ QgsAlignRasterLayerConfigDialog::QgsAlignRasterLayerConfigDialog()
   chkRescale = new QCheckBox( tr( "Rescale values according to the cell size" ), this );
 
   btnBox = new QDialogButtonBox( QDialogButtonBox::Ok | QDialogButtonBox::Cancel, Qt::Horizontal, this );
-  connect( btnBox, SIGNAL( accepted() ), this, SLOT( accept() ) );
-  connect( btnBox, SIGNAL( rejected() ), this, SLOT( reject() ) );
+  connect( btnBox, &QDialogButtonBox::accepted, this, &QDialog::accept );
+  connect( btnBox, &QDialogButtonBox::rejected, this, &QDialog::reject );
 
   layout->addWidget( new QLabel( tr( "Input raster layer:" ), this ) );
   layout->addWidget( cboLayers );
diff --git a/src/app/qgsapplayertreeviewmenuprovider.cpp b/src/app/qgsapplayertreeviewmenuprovider.cpp
index 47a5cd71887..2349491cb0b 100644
--- a/src/app/qgsapplayertreeviewmenuprovider.cpp
+++ b/src/app/qgsapplayertreeviewmenuprovider.cpp
@@ -170,7 +170,7 @@ QMenu *QgsAppLayerTreeViewMenuProvider::createContextMenu()
             colorWheel->setColor( singleRenderer->symbol()->color() );
             QgsColorWidgetAction *colorAction = new QgsColorWidgetAction( colorWheel, menuStyleManager, menuStyleManager );
             colorAction->setDismissOnColorSelection( false );
-            connect( colorAction, SIGNAL( colorChanged( const QColor & ) ), this, SLOT( setVectorSymbolColor( const QColor & ) ) );
+            connect( colorAction, &QgsColorWidgetAction::colorChanged, this, &QgsAppLayerTreeViewMenuProvider::setVectorSymbolColor );
             //store the layer id in action, so we can later retrieve the corresponding layer
             colorAction->setProperty( "layerId", vlayer->id() );
             menuStyleManager->addAction( colorAction );
@@ -184,14 +184,14 @@ QMenu *QgsAppLayerTreeViewMenuProvider::createContextMenu()
               recentColorAction->setProperty( "layerId", vlayer->id() );
               recentColorAction->setDismissOnColorSelection( false );
               menuStyleManager->addAction( recentColorAction );
-              connect( recentColorAction, SIGNAL( colorChanged( const QColor & ) ), this, SLOT( setVectorSymbolColor( const QColor & ) ) );
+              connect( recentColorAction, &QgsColorSwatchGridAction::colorChanged, this, &QgsAppLayerTreeViewMenuProvider::setVectorSymbolColor );
             }
 
             menuStyleManager->addSeparator();
             QAction *editSymbolAction = new QAction( tr( "Edit Symbol..." ), menuStyleManager );
             //store the layer id in action, so we can later retrieve the corresponding layer
             editSymbolAction->setProperty( "layerId", vlayer->id() );
-            connect( editSymbolAction, SIGNAL( triggered() ), this, SLOT( editVectorSymbol() ) );
+            connect( editSymbolAction, &QAction::triggered, this, &QgsAppLayerTreeViewMenuProvider::editVectorSymbol );
             menuStyleManager->addAction( editSymbolAction );
           }
         }
@@ -305,7 +305,7 @@ QMenu *QgsAppLayerTreeViewMenuProvider::createContextMenu()
         colorWheel->setColor( symbolNode->symbol()->color() );
         QgsColorWidgetAction *colorAction = new QgsColorWidgetAction( colorWheel, menu, menu );
         colorAction->setDismissOnColorSelection( false );
-        connect( colorAction, SIGNAL( colorChanged( const QColor & ) ), this, SLOT( setSymbolLegendNodeColor( const QColor & ) ) );
+        connect( colorAction, &QgsColorWidgetAction::colorChanged, this, &QgsAppLayerTreeViewMenuProvider::setSymbolLegendNodeColor );
         //store the layer id and rule key in action, so we can later retrieve the corresponding
         //legend node, if it still exists
         colorAction->setProperty( "layerId", symbolNode->layerNode()->layerId() );
@@ -322,7 +322,7 @@ QMenu *QgsAppLayerTreeViewMenuProvider::createContextMenu()
           recentColorAction->setProperty( "ruleKey", symbolNode->data( QgsLayerTreeModelLegendNode::RuleKeyRole ).toString() );
           recentColorAction->setDismissOnColorSelection( false );
           menu->addAction( recentColorAction );
-          connect( recentColorAction, SIGNAL( colorChanged( const QColor & ) ), this, SLOT( setSymbolLegendNodeColor( const QColor & ) ) );
+          connect( recentColorAction, &QgsColorSwatchGridAction::colorChanged, this, &QgsAppLayerTreeViewMenuProvider::setSymbolLegendNodeColor );
         }
 
         menu->addSeparator();
@@ -333,7 +333,7 @@ QMenu *QgsAppLayerTreeViewMenuProvider::createContextMenu()
       //legend node, if it still exists
       editSymbolAction->setProperty( "layerId", symbolNode->layerNode()->layerId() );
       editSymbolAction->setProperty( "ruleKey", symbolNode->data( QgsLayerTreeModelLegendNode::RuleKeyRole ).toString() );
-      connect( editSymbolAction, SIGNAL( triggered() ), this, SLOT( editSymbolLegendNodeSymbol() ) );
+      connect( editSymbolAction, &QAction::triggered, this, &QgsAppLayerTreeViewMenuProvider::editSymbolLegendNodeSymbol );
       menu->addAction( editSymbolAction );
     }
   }
diff --git a/src/app/qgsattributeactiondialog.cpp b/src/app/qgsattributeactiondialog.cpp
index eeb9d854cf6..b15dea77c5f 100644
--- a/src/app/qgsattributeactiondialog.cpp
+++ b/src/app/qgsattributeactiondialog.cpp
@@ -49,13 +49,13 @@ QgsAttributeActionDialog::QgsAttributeActionDialog( const QgsActionManager &acti
   mAttributeActionTable->setCornerButtonEnabled( false );
   mAttributeActionTable->setEditTriggers( QAbstractItemView::AnyKeyPressed | QAbstractItemView::SelectedClicked );
 
-  connect( mAttributeActionTable, SIGNAL( itemDoubleClicked( QTableWidgetItem * ) ), this, SLOT( itemDoubleClicked( QTableWidgetItem * ) ) );
-  connect( mAttributeActionTable, SIGNAL( itemSelectionChanged() ), this, SLOT( updateButtons() ) );
-  connect( mMoveUpButton, SIGNAL( clicked() ), this, SLOT( moveUp() ) );
-  connect( mMoveDownButton, SIGNAL( clicked() ), this, SLOT( moveDown() ) );
-  connect( mRemoveButton, SIGNAL( clicked() ), this, SLOT( remove() ) );
-  connect( mAddButton, SIGNAL( clicked( bool ) ), this, SLOT( insert() ) );
-  connect( mAddDefaultActionsButton, SIGNAL( clicked() ), this, SLOT( addDefaultActions() ) );
+  connect( mAttributeActionTable, &QTableWidget::itemDoubleClicked, this, &QgsAttributeActionDialog::itemDoubleClicked );
+  connect( mAttributeActionTable, &QTableWidget::itemSelectionChanged, this, &QgsAttributeActionDialog::updateButtons );
+  connect( mMoveUpButton, &QAbstractButton::clicked, this, &QgsAttributeActionDialog::moveUp );
+  connect( mMoveDownButton, &QAbstractButton::clicked, this, &QgsAttributeActionDialog::moveDown );
+  connect( mRemoveButton, &QAbstractButton::clicked, this, &QgsAttributeActionDialog::remove );
+  connect( mAddButton, &QAbstractButton::clicked, this, &QgsAttributeActionDialog::insert );
+  connect( mAddDefaultActionsButton, &QAbstractButton::clicked, this, &QgsAttributeActionDialog::addDefaultActions );
 
   init( actions, mLayer->attributeTableConfig() );
 }
diff --git a/src/app/qgsattributeactionpropertiesdialog.cpp b/src/app/qgsattributeactionpropertiesdialog.cpp
index 65fa5a1f589..bdcf4b7db04 100644
--- a/src/app/qgsattributeactionpropertiesdialog.cpp
+++ b/src/app/qgsattributeactionpropertiesdialog.cpp
@@ -207,11 +207,11 @@ void QgsAttributeActionPropertiesDialog::init( const QSet<QString> &actionScopes
   mFieldExpression->setGeomCalculator( myDa );
   mFieldExpression->registerExpressionContextGenerator( this );
 
-  connect( mBrowseButton, SIGNAL( clicked( bool ) ), this, SLOT( browse() ) );
-  connect( mInsertFieldOrExpression, SIGNAL( clicked( bool ) ), this, SLOT( insertExpressionOrField() ) );
-  connect( mActionName, SIGNAL( textChanged( QString ) ), this, SLOT( updateButtons() ) );
-  connect( mActionText, SIGNAL( textChanged() ), this, SLOT( updateButtons() ) );
-  connect( mChooseIconButton, SIGNAL( clicked( bool ) ), this, SLOT( chooseIcon() ) );
+  connect( mBrowseButton, &QAbstractButton::clicked, this, &QgsAttributeActionPropertiesDialog::browse );
+  connect( mInsertFieldOrExpression, &QAbstractButton::clicked, this, &QgsAttributeActionPropertiesDialog::insertExpressionOrField );
+  connect( mActionName, &QLineEdit::textChanged, this, &QgsAttributeActionPropertiesDialog::updateButtons );
+  connect( mActionText, &QsciScintilla::textChanged, this, &QgsAttributeActionPropertiesDialog::updateButtons );
+  connect( mChooseIconButton, &QAbstractButton::clicked, this, &QgsAttributeActionPropertiesDialog::chooseIcon );
 
   updateButtons();
 }
diff --git a/src/app/qgsattributetabledialog.cpp b/src/app/qgsattributetabledialog.cpp
index 18f5c8fab68..bde2a2bea14 100644
--- a/src/app/qgsattributetabledialog.cpp
+++ b/src/app/qgsattributetabledialog.cpp
@@ -170,41 +170,41 @@ QgsAttributeTableDialog::QgsAttributeTableDialog( QgsVectorLayer *layer, QWidget
   mActionEditedFilter->setIcon( filterIcon );
 
   // Connect filter signals
-  connect( mActionAdvancedFilter, SIGNAL( triggered() ), SLOT( filterExpressionBuilder() ) );
-  connect( mActionShowAllFilter, SIGNAL( triggered() ), SLOT( filterShowAll() ) );
-  connect( mActionSelectedFilter, SIGNAL( triggered() ), SLOT( filterSelected() ) );
-  connect( mActionVisibleFilter, SIGNAL( triggered() ), SLOT( filterVisible() ) );
-  connect( mActionEditedFilter, SIGNAL( triggered() ), SLOT( filterEdited() ) );
+  connect( mActionAdvancedFilter, &QAction::triggered, this, &QgsAttributeTableDialog::filterExpressionBuilder );
+  connect( mActionShowAllFilter, &QAction::triggered, this, &QgsAttributeTableDialog::filterShowAll );
+  connect( mActionSelectedFilter, &QAction::triggered, this, &QgsAttributeTableDialog::filterSelected );
+  connect( mActionVisibleFilter, &QAction::triggered, this, &QgsAttributeTableDialog::filterVisible );
+  connect( mActionEditedFilter, &QAction::triggered, this, &QgsAttributeTableDialog::filterEdited );
   connect( mFilterActionMapper, SIGNAL( mapped( QObject * ) ), SLOT( filterColumnChanged( QObject * ) ) );
-  connect( mFilterQuery, SIGNAL( returnPressed() ), SLOT( filterQueryAccepted() ) );
-  connect( mActionApplyFilter, SIGNAL( triggered() ), SLOT( filterQueryAccepted() ) );
-  connect( mActionSetStyles, SIGNAL( triggered() ), SLOT( openConditionalStyles() ) );
+  connect( mFilterQuery, &QLineEdit::returnPressed, this, &QgsAttributeTableDialog::filterQueryAccepted );
+  connect( mActionApplyFilter, &QAction::triggered, this, &QgsAttributeTableDialog::filterQueryAccepted );
+  connect( mActionSetStyles, &QAction::triggered, this, &QgsAttributeTableDialog::openConditionalStyles );
 
   // info from layer to table
-  connect( mLayer, SIGNAL( editingStarted() ), this, SLOT( editingToggled() ) );
-  connect( mLayer, SIGNAL( editingStopped() ), this, SLOT( editingToggled() ) );
-  connect( mLayer, SIGNAL( destroyed() ), this, SLOT( close() ) );
+  connect( mLayer, &QgsVectorLayer::editingStarted, this, &QgsAttributeTableDialog::editingToggled );
+  connect( mLayer, &QgsVectorLayer::editingStopped, this, &QgsAttributeTableDialog::editingToggled );
+  connect( mLayer, &QObject::destroyed, this, &QWidget::close );
   connect( mLayer, &QgsVectorLayer::selectionChanged, this, &QgsAttributeTableDialog::updateTitle );
-  connect( mLayer, SIGNAL( featureAdded( QgsFeatureId ) ), this, SLOT( updateTitle() ) );
-  connect( mLayer, SIGNAL( featuresDeleted( QgsFeatureIds ) ), this, SLOT( updateTitle() ) );
-  connect( mLayer, SIGNAL( attributeAdded( int ) ), this, SLOT( columnBoxInit() ) );
-  connect( mLayer, SIGNAL( attributeDeleted( int ) ), this, SLOT( columnBoxInit() ) );
+  connect( mLayer, &QgsVectorLayer::featureAdded, this, &QgsAttributeTableDialog::updateTitle );
+  connect( mLayer, &QgsVectorLayer::featuresDeleted, this, &QgsAttributeTableDialog::updateTitle );
+  connect( mLayer, &QgsVectorLayer::attributeAdded, this, &QgsAttributeTableDialog::columnBoxInit );
+  connect( mLayer, &QgsVectorLayer::attributeDeleted, this, &QgsAttributeTableDialog::columnBoxInit );
   connect( mLayer, &QgsVectorLayer::readOnlyChanged, this, &QgsAttributeTableDialog::editingToggled );
 
   // connect table info to window
-  connect( mMainView, SIGNAL( filterChanged() ), this, SLOT( updateTitle() ) );
-  connect( mMainView, SIGNAL( filterExpressionSet( QString, QgsAttributeForm::FilterType ) ), this, SLOT( formFilterSet( QString, QgsAttributeForm::FilterType ) ) );
-  connect( mMainView, SIGNAL( formModeChanged( QgsAttributeForm::Mode ) ), this, SLOT( viewModeChanged( QgsAttributeForm::Mode ) ) );
+  connect( mMainView, &QgsDualView::filterChanged, this, &QgsAttributeTableDialog::updateTitle );
+  connect( mMainView, &QgsDualView::filterExpressionSet, this, &QgsAttributeTableDialog::formFilterSet );
+  connect( mMainView, &QgsDualView::formModeChanged, this, &QgsAttributeTableDialog::viewModeChanged );
 
   // info from table to application
-  connect( this, SIGNAL( saveEdits( QgsMapLayer * ) ), QgisApp::instance(), SLOT( saveEdits( QgsMapLayer * ) ) );
+  connect( this, &QgsAttributeTableDialog::saveEdits, this, [ = ] { QgisApp::instance()->saveEdits(); } );
 
   bool myDockFlag = settings.value( QStringLiteral( "qgis/dockAttributeTable" ), false ).toBool();
   if ( myDockFlag )
   {
     mDock = new QgsAttributeTableDock( tr( "%1 (%n Feature(s))", "feature count", mMainView->featureCount() ).arg( mLayer->name() ), QgisApp::instance() );
     mDock->setWidget( this );
-    connect( this, SIGNAL( destroyed() ), mDock, SLOT( close() ) );
+    connect( this, &QObject::destroyed, mDock, &QWidget::close );
     QgisApp::instance()->addDockWidget( Qt::BottomDockWidgetArea, mDock );
   }
 
@@ -283,11 +283,11 @@ QgsAttributeTableDialog::QgsAttributeTableDialog( QgsVectorLayer *layer, QWidget
   mFieldCombo->setFilters( QgsFieldProxyModel::AllTypes | QgsFieldProxyModel::HideReadOnly );
   mFieldCombo->setLayer( mLayer );
 
-  connect( mRunFieldCalc, SIGNAL( clicked() ), this, SLOT( updateFieldFromExpression() ) );
-  connect( mRunFieldCalcSelected, SIGNAL( clicked() ), this, SLOT( updateFieldFromExpressionSelected() ) );
+  connect( mRunFieldCalc, &QAbstractButton::clicked, this, &QgsAttributeTableDialog::updateFieldFromExpression );
+  connect( mRunFieldCalcSelected, &QAbstractButton::clicked, this, &QgsAttributeTableDialog::updateFieldFromExpressionSelected );
   // NW TODO Fix in 2.6 - Doesn't work with field model for some reason.
 //  connect( mUpdateExpressionText, SIGNAL( returnPressed() ), this, SLOT( updateFieldFromExpression() ) );
-  connect( mUpdateExpressionText, SIGNAL( fieldChanged( QString, bool ) ), this, SLOT( updateButtonStatus( QString, bool ) ) );
+  connect( mUpdateExpressionText, static_cast < void ( QgsFieldExpressionWidget::* )( const QString &, bool ) > ( &QgsFieldExpressionWidget::fieldChanged ), this, &QgsAttributeTableDialog::updateButtonStatus );
   mUpdateExpressionText->setLayer( mLayer );
   mUpdateExpressionText->setLeftHandButtonStyle( true );
 
@@ -299,8 +299,8 @@ QgsAttributeTableDialog::QgsAttributeTableDialog( QgsVectorLayer *layer, QWidget
   mMainView->setView( static_cast< QgsDualView::ViewMode >( initialView ) );
   mMainViewButtonGroup->button( initialView )->setChecked( true );
 
-  connect( mActionToggleMultiEdit, SIGNAL( toggled( bool ) ), mMainView, SLOT( setMultiEditEnabled( bool ) ) );
-  connect( mActionSearchForm, SIGNAL( toggled( bool ) ), mMainView, SLOT( toggleSearchMode( bool ) ) );
+  connect( mActionToggleMultiEdit, &QAction::toggled, mMainView, &QgsDualView::setMultiEditEnabled );
+  connect( mActionSearchForm, &QAction::toggled, mMainView, &QgsDualView::toggleSearchMode );
   updateMultiEditButtonState();
 
   if ( mLayer->editFormConfig().layout() == QgsEditFormConfig::UiFileLayout )
@@ -566,12 +566,12 @@ void QgsAttributeTableDialog::filterColumnChanged( QObject *filterAction )
                                 createSearchWidget( setup.type(), mLayer, fldIdx, setup.config(), mFilterContainer, mEditorContext );
   if ( mCurrentSearchWidgetWrapper->applyDirectly() )
   {
-    connect( mCurrentSearchWidgetWrapper, SIGNAL( expressionChanged( QString ) ), SLOT( filterQueryChanged( QString ) ) );
+    connect( mCurrentSearchWidgetWrapper, &QgsSearchWidgetWrapper::expressionChanged, this, &QgsAttributeTableDialog::filterQueryChanged );
     mApplyFilterButton->setVisible( false );
   }
   else
   {
-    connect( mCurrentSearchWidgetWrapper, SIGNAL( expressionChanged( QString ) ), SLOT( filterQueryAccepted() ) );
+    connect( mCurrentSearchWidgetWrapper, &QgsSearchWidgetWrapper::expressionChanged, this, &QgsAttributeTableDialog::filterQueryAccepted );
     mApplyFilterButton->setVisible( true );
   }