diff --git a/python/core/expression/qgsexpressionnode.sip b/python/core/expression/qgsexpressionnode.sip
index 4f209afdd3d..b11de541159 100644
--- a/python/core/expression/qgsexpressionnode.sip
+++ b/python/core/expression/qgsexpressionnode.sip
@@ -137,7 +137,7 @@ Takes ownership of the provided node
  :rtype: list of str
 %End
 
-        QgsExpressionNode::NodeList *clone() const;
+        QgsExpressionNode::NodeList *clone() const /Factory/;
 %Docstring
 Creates a deep copy of this list. Ownership is transferred to the caller
  :rtype: QgsExpressionNode.NodeList
diff --git a/python/core/expression/qgsexpressionnodeimpl.sip b/python/core/expression/qgsexpressionnodeimpl.sip
index bd4e774c1b1..685975b990a 100644
--- a/python/core/expression/qgsexpressionnodeimpl.sip
+++ b/python/core/expression/qgsexpressionnodeimpl.sip
@@ -49,7 +49,7 @@ class QgsExpressionNodeUnaryOperator : QgsExpressionNode
     virtual QSet<QString> referencedColumns() const;
     virtual QSet<QString> referencedVariables() const;
     virtual bool needsGeometry() const;
-    virtual QgsExpressionNode *clone() const;
+    virtual QgsExpressionNode *clone() const /Factory/;
 
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const;
 
@@ -131,7 +131,7 @@ class QgsExpressionNodeBinaryOperator : QgsExpressionNode
     virtual QSet<QString> referencedColumns() const;
     virtual QSet<QString> referencedVariables() const;
     virtual bool needsGeometry() const;
-    virtual QgsExpressionNode *clone() const;
+    virtual QgsExpressionNode *clone() const /Factory/;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const;
 
     int precedence() const;
@@ -187,7 +187,7 @@ class QgsExpressionNodeInOperator : QgsExpressionNode
     virtual QSet<QString> referencedColumns() const;
     virtual QSet<QString> referencedVariables() const;
     virtual bool needsGeometry() const;
-    virtual QgsExpressionNode *clone() const;
+    virtual QgsExpressionNode *clone() const /Factory/;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const;
 
 };
@@ -225,7 +225,7 @@ class QgsExpressionNodeFunction : QgsExpressionNode
     virtual QSet<QString> referencedColumns() const;
     virtual QSet<QString> referencedVariables() const;
     virtual bool needsGeometry() const;
-    virtual QgsExpressionNode *clone() const;
+    virtual QgsExpressionNode *clone() const /Factory/;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const;
 
     static bool validateParams( int fnIndex, QgsExpressionNode::NodeList *args, QString &error );
@@ -259,7 +259,7 @@ The value of the literal.
     virtual QSet<QString> referencedColumns() const;
     virtual QSet<QString> referencedVariables() const;
     virtual bool needsGeometry() const;
-    virtual QgsExpressionNode *clone() const;
+    virtual QgsExpressionNode *clone() const /Factory/;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const;
 
 };
@@ -288,7 +288,7 @@ The name of the column.
     virtual QSet<QString> referencedVariables() const;
     virtual bool needsGeometry() const;
 
-    virtual QgsExpressionNode *clone() const;
+    virtual QgsExpressionNode *clone() const /Factory/;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const;
 
 };
@@ -315,7 +315,7 @@ class QgsExpressionNodeCondition : QgsExpressionNode
         ~WhenThen();
 
 
-        QgsExpressionNodeCondition::WhenThen *clone() const;
+        QgsExpressionNodeCondition::WhenThen *clone() const /Factory/;
 %Docstring
  Get a deep copy of this WhenThen combination.
  :rtype: QgsExpressionNodeCondition.WhenThen
@@ -342,7 +342,7 @@ class QgsExpressionNodeCondition : QgsExpressionNode
     virtual QSet<QString> referencedColumns() const;
     virtual QSet<QString> referencedVariables() const;
     virtual bool needsGeometry() const;
-    virtual QgsExpressionNode *clone() const;
+    virtual QgsExpressionNode *clone() const /Factory/;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const;
 
 };
diff --git a/python/core/qgscolorramp.sip b/python/core/qgscolorramp.sip
index 2a975336720..d88365c3ef5 100644
--- a/python/core/qgscolorramp.sip
+++ b/python/core/qgscolorramp.sip
@@ -155,7 +155,7 @@ Creates a new QgsColorRamp from a map of properties
     virtual QColor color( double value ) const;
     virtual QString type() const;
     virtual void invert();
-    virtual QgsGradientColorRamp *clone() const;
+    virtual QgsGradientColorRamp *clone() const /Factory/;
     virtual QgsStringMap properties() const;
 
     QColor color1() const;
diff --git a/python/core/qgspropertytransformer.sip b/python/core/qgspropertytransformer.sip
index 02634a5ec3f..39da3b5f2d0 100644
--- a/python/core/qgspropertytransformer.sip
+++ b/python/core/qgspropertytransformer.sip
@@ -345,7 +345,7 @@ class QgsGenericNumericTransformer : QgsPropertyTransformer
 %End
 
     virtual Type transformerType() const;
-    virtual QgsGenericNumericTransformer *clone();
+    virtual QgsGenericNumericTransformer *clone() /Factory/;
     virtual QVariant toVariant() const;
     virtual bool loadVariant( const QVariant &definition );
     virtual QVariant transform( const QgsExpressionContext &context, const QVariant &value ) const;
diff --git a/src/core/expression/qgsexpressionnode.h b/src/core/expression/qgsexpressionnode.h
index 2aa455c5bd4..323c5702c6f 100644
--- a/src/core/expression/qgsexpressionnode.h
+++ b/src/core/expression/qgsexpressionnode.h
@@ -143,7 +143,7 @@ class CORE_EXPORT QgsExpressionNode SIP_ABSTRACT
         QStringList names() const { return mNameList; }
 
         //! Creates a deep copy of this list. Ownership is transferred to the caller
-        QgsExpressionNode::NodeList *clone() const;
+        QgsExpressionNode::NodeList *clone() const SIP_FACTORY;
 
         virtual QString dump() const;
 
diff --git a/src/core/expression/qgsexpressionnodeimpl.h b/src/core/expression/qgsexpressionnodeimpl.h
index 2083576360c..b49937100ef 100644
--- a/src/core/expression/qgsexpressionnodeimpl.h
+++ b/src/core/expression/qgsexpressionnodeimpl.h
@@ -57,7 +57,7 @@ class CORE_EXPORT QgsExpressionNodeUnaryOperator : public QgsExpressionNode
     virtual QSet<QString> referencedColumns() const override;
     virtual QSet<QString> referencedVariables() const override;
     virtual bool needsGeometry() const override;
-    virtual QgsExpressionNode *clone() const override;
+    virtual QgsExpressionNode *clone() const override SIP_FACTORY;
 
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
 
@@ -140,7 +140,7 @@ class CORE_EXPORT QgsExpressionNodeBinaryOperator : public QgsExpressionNode
     virtual QSet<QString> referencedColumns() const override;
     virtual QSet<QString> referencedVariables() const override;
     virtual bool needsGeometry() const override;
-    virtual QgsExpressionNode *clone() const override;
+    virtual QgsExpressionNode *clone() const override SIP_FACTORY;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
 
     int precedence() const;
@@ -198,7 +198,7 @@ class CORE_EXPORT QgsExpressionNodeInOperator : public QgsExpressionNode
     virtual QSet<QString> referencedColumns() const override;
     virtual QSet<QString> referencedVariables() const override;
     virtual bool needsGeometry() const override;
-    virtual QgsExpressionNode *clone() const override;
+    virtual QgsExpressionNode *clone() const override SIP_FACTORY;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
 
   private:
@@ -232,7 +232,7 @@ class CORE_EXPORT QgsExpressionNodeFunction : public QgsExpressionNode
     virtual QSet<QString> referencedColumns() const override;
     virtual QSet<QString> referencedVariables() const override;
     virtual bool needsGeometry() const override;
-    virtual QgsExpressionNode *clone() const override;
+    virtual QgsExpressionNode *clone() const override SIP_FACTORY;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
 
     //! Tests whether the provided argument list is valid for the matching function
@@ -264,7 +264,7 @@ class CORE_EXPORT QgsExpressionNodeLiteral : public QgsExpressionNode
     virtual QSet<QString> referencedColumns() const override;
     virtual QSet<QString> referencedVariables() const override;
     virtual bool needsGeometry() const override;
-    virtual QgsExpressionNode *clone() const override;
+    virtual QgsExpressionNode *clone() const override SIP_FACTORY;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
 
   private:
@@ -293,7 +293,7 @@ class CORE_EXPORT QgsExpressionNodeColumnRef : public QgsExpressionNode
     virtual QSet<QString> referencedVariables() const override;
     virtual bool needsGeometry() const override;
 
-    virtual QgsExpressionNode *clone() const override;
+    virtual QgsExpressionNode *clone() const override SIP_FACTORY;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
 
   private:
@@ -324,7 +324,7 @@ class CORE_EXPORT QgsExpressionNodeCondition : public QgsExpressionNode
         /**
          * Get a deep copy of this WhenThen combination.
          */
-        QgsExpressionNodeCondition::WhenThen *clone() const;
+        QgsExpressionNodeCondition::WhenThen *clone() const SIP_FACTORY;
 
       private:
 #ifdef SIP_RUN
@@ -360,7 +360,7 @@ class CORE_EXPORT QgsExpressionNodeCondition : public QgsExpressionNode
     virtual QSet<QString> referencedColumns() const override;
     virtual QSet<QString> referencedVariables() const override;
     virtual bool needsGeometry() const override;
-    virtual QgsExpressionNode *clone() const override;
+    virtual QgsExpressionNode *clone() const override SIP_FACTORY;
     virtual bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
 
   private:
diff --git a/src/core/qgscolorramp.h b/src/core/qgscolorramp.h
index 4eb97ab30ee..ee0b81641b1 100644
--- a/src/core/qgscolorramp.h
+++ b/src/core/qgscolorramp.h
@@ -149,7 +149,7 @@ class CORE_EXPORT QgsGradientColorRamp : public QgsColorRamp
     virtual QColor color( double value ) const override;
     virtual QString type() const override { return QStringLiteral( "gradient" ); }
     virtual void invert() override;
-    virtual QgsGradientColorRamp *clone() const override;
+    virtual QgsGradientColorRamp *clone() const override SIP_FACTORY;
     virtual QgsStringMap properties() const override;
 
     /** Returns the gradient start color.
diff --git a/src/core/qgspropertytransformer.h b/src/core/qgspropertytransformer.h
index 44a32cff96e..e3e03d43030 100644
--- a/src/core/qgspropertytransformer.h
+++ b/src/core/qgspropertytransformer.h
@@ -367,7 +367,7 @@ class CORE_EXPORT QgsGenericNumericTransformer : public QgsPropertyTransformer
     QgsGenericNumericTransformer &operator=( const QgsGenericNumericTransformer &other );
 
     virtual Type transformerType() const override { return GenericNumericTransformer; }
-    virtual QgsGenericNumericTransformer *clone() override;
+    virtual QgsGenericNumericTransformer *clone() override SIP_FACTORY;
     virtual QVariant toVariant() const override;
     virtual bool loadVariant( const QVariant &definition ) override;
     virtual QVariant transform( const QgsExpressionContext &context, const QVariant &value ) const override;
diff --git a/src/core/symbology-ng/qgs25drenderer.h b/src/core/symbology-ng/qgs25drenderer.h
index 70656049bde..091664228c1 100644
--- a/src/core/symbology-ng/qgs25drenderer.h
+++ b/src/core/symbology-ng/qgs25drenderer.h
@@ -42,7 +42,7 @@ class CORE_EXPORT Qgs25DRenderer : public QgsFeatureRenderer
     void stopRender( QgsRenderContext &context ) override;
 
     QSet<QString> usedAttributes( const QgsRenderContext &context ) const override;
-    QgsFeatureRenderer *clone() const override;
+    QgsFeatureRenderer *clone() const override SIP_FACTORY;
 
     virtual QgsSymbol *symbolForFeature( QgsFeature &feature, QgsRenderContext &context ) override;
     virtual QgsSymbolList symbols( QgsRenderContext &context ) override;
diff --git a/src/core/symbology-ng/qgsfillsymbollayer.h b/src/core/symbology-ng/qgsfillsymbollayer.h
index e06d5fbeb9f..89dce19277b 100644
--- a/src/core/symbology-ng/qgsfillsymbollayer.h
+++ b/src/core/symbology-ng/qgsfillsymbollayer.h
@@ -661,7 +661,7 @@ class CORE_EXPORT QgsRasterFillSymbolLayer: public QgsImageFillSymbolLayer
     void startRender( QgsSymbolRenderContext &context ) override;
     void stopRender( QgsSymbolRenderContext &context ) override;
     QgsStringMap properties() const override;
-    QgsRasterFillSymbolLayer *clone() const override;
+    QgsRasterFillSymbolLayer *clone() const override SIP_FACTORY;
     virtual double estimateMaxBleed( const QgsRenderContext &context ) const override;
 
     //override QgsImageFillSymbolLayer's support for sub symbols
diff --git a/src/core/symbology-ng/qgsgeometrygeneratorsymbollayer.h b/src/core/symbology-ng/qgsgeometrygeneratorsymbollayer.h
index 20981b2cbbb..aeb6bbe5e25 100644
--- a/src/core/symbology-ng/qgsgeometrygeneratorsymbollayer.h
+++ b/src/core/symbology-ng/qgsgeometrygeneratorsymbollayer.h
@@ -51,7 +51,7 @@ class CORE_EXPORT QgsGeometryGeneratorSymbolLayer : public QgsSymbolLayer
 
     void stopRender( QgsSymbolRenderContext &context ) override;
 
-    QgsSymbolLayer *clone() const override;
+    QgsSymbolLayer *clone() const override SIP_FACTORY;
 
     QgsStringMap properties() const override;
 
diff --git a/src/core/symbology-ng/qgslinesymbollayer.h b/src/core/symbology-ng/qgslinesymbollayer.h
index 0430a4d8c31..bfcc64ef053 100644
--- a/src/core/symbology-ng/qgslinesymbollayer.h
+++ b/src/core/symbology-ng/qgslinesymbollayer.h
@@ -201,7 +201,7 @@ class CORE_EXPORT QgsMarkerLineSymbolLayer : public QgsLineSymbolLayer
 
     QgsStringMap properties() const override;
 
-    QgsMarkerLineSymbolLayer *clone() const override;
+    QgsMarkerLineSymbolLayer *clone() const override SIP_FACTORY;
 
     void toSld( QDomDocument &doc, QDomElement &element, const QgsStringMap &props ) const override;
 
diff --git a/src/core/symbology-ng/qgspointclusterrenderer.h b/src/core/symbology-ng/qgspointclusterrenderer.h
index e8faa35ee9e..c09386fe475 100644
--- a/src/core/symbology-ng/qgspointclusterrenderer.h
+++ b/src/core/symbology-ng/qgspointclusterrenderer.h
@@ -33,7 +33,7 @@ class CORE_EXPORT QgsPointClusterRenderer: public QgsPointDistanceRenderer
 
     QgsPointClusterRenderer();
 
-    QgsPointClusterRenderer *clone() const override;
+    QgsPointClusterRenderer *clone() const override SIP_FACTORY;
     virtual void startRender( QgsRenderContext &context, const QgsFields &fields ) override;
     void stopRender( QgsRenderContext &context ) override;
     QDomElement save( QDomDocument &doc, const QgsReadWriteContext &context ) override;
diff --git a/src/core/symbology-ng/qgspointdisplacementrenderer.h b/src/core/symbology-ng/qgspointdisplacementrenderer.h
index 612d998a49c..2d73d75f521 100644
--- a/src/core/symbology-ng/qgspointdisplacementrenderer.h
+++ b/src/core/symbology-ng/qgspointdisplacementrenderer.h
@@ -43,7 +43,7 @@ class CORE_EXPORT QgsPointDisplacementRenderer: public QgsPointDistanceRenderer
      */
     QgsPointDisplacementRenderer( const QString &labelAttributeName = QString() );
 
-    QgsPointDisplacementRenderer *clone() const override;
+    QgsPointDisplacementRenderer *clone() const override SIP_FACTORY;
     virtual void startRender( QgsRenderContext &context, const QgsFields &fields ) override;
     void stopRender( QgsRenderContext &context ) override;
     QDomElement save( QDomDocument &doc, const QgsReadWriteContext &context ) override;
diff --git a/src/core/symbology-ng/qgsrulebasedrenderer.h b/src/core/symbology-ng/qgsrulebasedrenderer.h
index ee71f2837d8..8658b150180 100644
--- a/src/core/symbology-ng/qgsrulebasedrenderer.h
+++ b/src/core/symbology-ng/qgsrulebasedrenderer.h
@@ -254,7 +254,7 @@ class CORE_EXPORT QgsRuleBasedRenderer : public QgsFeatureRenderer
         void setActive( bool state ) { mIsActive = state; }
 
         //! clone this rule, return new instance
-        Rule *clone() const;
+        Rule *clone() const SIP_FACTORY;
 
         void toSld( QDomDocument &doc, QDomElement &element, QgsStringMap props ) const;
 
diff --git a/src/server/qgsaccesscontrol.h b/src/server/qgsaccesscontrol.h
index 34f6c910aae..f944d819c6d 100644
--- a/src/server/qgsaccesscontrol.h
+++ b/src/server/qgsaccesscontrol.h
@@ -71,7 +71,7 @@ class SERVER_EXPORT QgsAccessControl : public QgsFeatureFilterProvider
     /** Return a clone of the object
      * \returns A clone
      */
-    QgsFeatureFilterProvider *clone() const;
+    QgsFeatureFilterProvider *clone() const SIP_FACTORY;
 
     /** Return an additional subset string (typically SQL) filter
      * \param layer the layer to control