do not hold a pointer to an QGraphicsItem within a QGraphicsItem

since map canvas is deleting them all, this is causing a crash when trying to delete the already deleted item in the parent item

python/gui/auto_generated/qgsadvanceddigitizingcanvasitem.sip.in

@@ -10,6 +10,7 @@
 
 
 
+
 class QgsAdvancedDigitizingCanvasItem : QgsMapCanvasItem
 {
 %Docstring
@@ -25,8 +26,6 @@ The QgsAdvancedDigitizingCanvasItem class draws the graphical elements of the CA
     virtual void paint( QPainter *painter );
 
 
-  protected:
-
 };
 
 /************************************************************************

src/gui/qgsadvanceddigitizingcanvasitem.cpp

@@ -28,7 +28,6 @@ QgsAdvancedDigitizingCanvasItem::QgsAdvancedDigitizingCanvasItem( QgsMapCanvas *
   , mSnapPen( QPen( QColor( 127, 0, 0, 150 ), 1 ) )
   , mSnapLinePen( QPen( QColor( 127, 0, 0, 150 ), 1, Qt::DashLine ) )
   , mCursorPen( QPen( QColor( 127, 127, 127, 255 ), 1 ) )
-  , mSnapIndicator( qgis::make_unique< QgsSnapIndicator>( canvas ) )
   , mAdvancedDigitizingDockWidget( cadDockWidget )
 {
 }
@@ -253,15 +252,4 @@ void QgsAdvancedDigitizingCanvasItem::paint( QPainter *painter )
     painter->drawLine( curPointPix + QPointF( -5, +5 ),
                        curPointPix + QPointF( +5, -5 ) );
   }
-
-
-  QgsPointLocator::Match match = mAdvancedDigitizingDockWidget->mapPointMatch();
-  if ( match.isValid() )
-  {
-    mSnapIndicator->setMatch( match );
-    mSnapIndicator->setVisible( true );
-  }
-  else
-    mSnapIndicator->setVisible( false );
-
 }

src/gui/qgsadvanceddigitizingcanvasitem.h

@@ -20,7 +20,7 @@
 
 #include "qgsmapcanvasitem.h"
 #include "qgis_gui.h"
-#include "qgssnapindicator.h"
+
 
 class QgsAdvancedDigitizingDockWidget;
 
@@ -35,17 +35,13 @@ class GUI_EXPORT QgsAdvancedDigitizingCanvasItem : public QgsMapCanvasItem
 
     void paint( QPainter *painter ) override;
 
-  protected:
+  private:
     QPen mLockedPen;
     QPen mConstruction1Pen;
     QPen mConstruction2Pen;
     QPen mSnapPen;
     QPen mSnapLinePen;
     QPen mCursorPen;
-    //! Snapping indicators
-    std::unique_ptr<QgsSnapIndicator> mSnapIndicator;
-
-  private:
     QgsAdvancedDigitizingDockWidget *mAdvancedDigitizingDockWidget = nullptr;
 };
 

src/gui/qgsadvanceddigitizingdockwidget.cpp

@@ -42,6 +42,7 @@
 QgsAdvancedDigitizingDockWidget::QgsAdvancedDigitizingDockWidget( QgsMapCanvas *canvas, QWidget *parent )
   : QgsDockWidget( parent )
   , mMapCanvas( canvas )
+  , mSnapIndicator( qgis::make_unique< QgsSnapIndicator>( canvas ) )
   , mCommonAngleConstraint( QgsSettings().value( QStringLiteral( "/Cad/CommonAngle" ), 90 ).toDouble() )
 {
   setupUi( this );
@@ -670,6 +671,17 @@ bool QgsAdvancedDigitizingDockWidget::applyConstraints( QgsMapMouseEvent *e )
   e->setMapPoint( point );
 
   mSnapMatch = context.snappingUtils->snapToMap( point );
+
+  if ( mSnapMatch.isValid() )
+  {
+    mSnapIndicator->setMatch( mSnapMatch );
+    mSnapIndicator->setVisible( true );
+  }
+  else
+  {
+    mSnapIndicator->setVisible( false );
+  }
+
   /*
    * Constraints are applied in 2D, they are always called when using the tool
    * but they do not take into account if when you snap on a vertex it has

src/gui/qgsadvanceddigitizingdockwidget.h

@@ -28,6 +28,7 @@
 #include "qgsmessagebaritem.h"
 #include "qgspointxy.h"
 #include "qgspointlocator.h"
+#include "qgssnapindicator.h"
 
 
 class QgsAdvancedDigitizingCanvasItem;
@@ -702,6 +703,8 @@ class GUI_EXPORT QgsAdvancedDigitizingDockWidget : public QgsDockWidget, private
 
     QgsMapCanvas *mMapCanvas = nullptr;
     QgsAdvancedDigitizingCanvasItem *mCadPaintItem = nullptr;
+    //! Snapping indicator
+    std::unique_ptr<QgsSnapIndicator> mSnapIndicator;
 
     CadCapacities mCapacities = nullptr;