fix duplicate layer

python/core/auto_generated/symbology/qgsfillsymbollayer.sip.in

@@ -803,7 +803,7 @@ Returns the units used for the offset of the shapeburst fill.
     QgsShapeburstFillSymbolLayer( const QgsShapeburstFillSymbolLayer &other );
 };
 
-class QgsImageFillSymbolLayer: QgsFillSymbolLayer
+class QgsImageFillSymbolLayer: QgsFillSymbolLayer /Abstract/
 {
 %Docstring(signature="appended")
 Base class for polygon renderers generating texture images
@@ -2818,8 +2818,6 @@ Sets whether point markers should be ``clipped`` to the current part boundary on
     QgsCentroidFillSymbolLayer( const QgsCentroidFillSymbolLayer &other );
 };
 
-
-
 /************************************************************************
  * This file has been generated automatically from                      *
  *                                                                      *

python/core/auto_generated/symbology/qgssymbollayerutils.sip.in

@@ -1049,6 +1049,27 @@ to new ones.
 %Docstring
 Remove recursively unique id from all ``symbol`` symbol layers and set an empty string instead
 
+.. versionadded:: 3.30
+%End
+
+    static void clearSymbolLayerIds( QgsSymbolLayer *symbolLayer );
+%Docstring
+Remove recursively unique id from ``symbolLayer`` and its children and set an empty string instead
+
+.. versionadded:: 3.30
+%End
+
+    static void resetSymbolLayerIds( QgsSymbol *symbol );
+%Docstring
+Regenerate recursively unique id from all ``symbol`` symbol layers
+
+.. versionadded:: 3.30
+%End
+
+    static void resetSymbolLayerIds( QgsSymbolLayer *symbolLayer );
+%Docstring
+Regenerate recursively unique id from ``symbolLayer`` and its children
+
 .. versionadded:: 3.30
 %End
 

src/core/symbology/qgsfillsymbollayer.h

@@ -776,7 +776,7 @@ class CORE_EXPORT QgsShapeburstFillSymbolLayer : public QgsFillSymbolLayer
  * \ingroup core
  * \brief Base class for polygon renderers generating texture images
 */
-class CORE_EXPORT QgsImageFillSymbolLayer: public QgsFillSymbolLayer
+class CORE_EXPORT QgsImageFillSymbolLayer: public QgsFillSymbolLayer SIP_ABSTRACT
 {
   public:
 
@@ -2550,5 +2550,3 @@ class CORE_EXPORT QgsCentroidFillSymbolLayer : public QgsFillSymbolLayer
 };
 
 #endif
-
-

src/core/symbology/qgssymbollayerutils.cpp

@@ -5446,20 +5446,43 @@ void QgsSymbolLayerUtils::fixOldSymbolLayerReferences( const QMap<QString, QgsMa
   }
 }
 
-void QgsSymbolLayerUtils::clearSymbolLayerIds( QgsSymbol *symbol )
+template <typename Functor>
+void changeSymbolLayerIds( QgsSymbolLayer *sl, Functor &&generateId )
+{
+  sl->setId( generateId() );
+
+  // recurse over sub symbols
+  QgsSymbol *subSymbol = sl->subSymbol();
+  if ( subSymbol )
+    changeSymbolLayerIds( subSymbol, generateId );
+}
+
+template <typename Functor>
+void changeSymbolLayerIds( QgsSymbol *symbol, Functor &&generateId )
 {
   if ( !symbol )
     return;
 
   for ( int idx = 0; idx < symbol->symbolLayerCount(); idx++ )
-  {
-    QgsSymbolLayer *sl = symbol->symbolLayer( idx );
-
-    sl->setId( QString() );
-
-    // recurse over sub symbols
-    QgsSymbol *subSymbol = const_cast<QgsSymbolLayer *>( sl )->subSymbol();
-    if ( subSymbol )
-      clearSymbolLayerIds( subSymbol );
-  }
+    changeSymbolLayerIds( symbol->symbolLayer( idx ), generateId );
+}
+
+void QgsSymbolLayerUtils::clearSymbolLayerIds( QgsSymbol *symbol )
+{
+  changeSymbolLayerIds( symbol, []() { return QString(); } );
+}
+
+void QgsSymbolLayerUtils::clearSymbolLayerIds( QgsSymbolLayer *symbolLayer )
+{
+  changeSymbolLayerIds( symbolLayer, []() { return QString(); } );
+}
+
+void QgsSymbolLayerUtils::resetSymbolLayerIds( QgsSymbolLayer *symbolLayer )
+{
+  changeSymbolLayerIds( symbolLayer, []() { return QUuid::createUuid().toString(); } );
+}
+
+void QgsSymbolLayerUtils::resetSymbolLayerIds( QgsSymbol *symbol )
+{
+  changeSymbolLayerIds( symbol, []() { return QUuid::createUuid().toString(); } );
 }

src/core/symbology/qgssymbollayerutils.h

@@ -943,6 +943,24 @@ class CORE_EXPORT QgsSymbolLayerUtils
      */
     static void clearSymbolLayerIds( QgsSymbol *symbol );
 
+    /**
+     * Remove recursively unique id from \a symbolLayer and its children and set an empty string instead
+     * \since QGIS 3.30
+     */
+    static void clearSymbolLayerIds( QgsSymbolLayer *symbolLayer );
+
+    /**
+     * Regenerate recursively unique id from all \a symbol symbol layers
+     * \since QGIS 3.30
+     */
+    static void resetSymbolLayerIds( QgsSymbol *symbol );
+
+    /**
+     * Regenerate recursively unique id from \a symbolLayer and its children
+     * \since QGIS 3.30
+     */
+    static void resetSymbolLayerIds( QgsSymbolLayer *symbolLayer );
+
     ///@cond PRIVATE
 #ifndef SIP_RUN
     static QgsProperty rotateWholeSymbol( double additionalRotation, const QgsProperty &property )

src/gui/symbology/qgssymbolselectordialog.cpp

@@ -721,6 +721,7 @@ void QgsSymbolSelectorWidget::duplicateLayer()
   QgsSymbol *parentSymbol = item->symbol();
 
   QgsSymbolLayer *newLayer = source->clone();
+  QgsSymbolLayerUtils::resetSymbolLayerIds( newLayer );
   if ( insertIdx == -1 )
     parentSymbol->appendSymbolLayer( newLayer );
   else

tests/src/python/test_qgssymbollayerutils.py

@@ -736,6 +736,40 @@ class PyQgsSymbolLayerUtils(unittest.TestCase):
             self.assertEqual(res_size.width(), int(exp_width))
             self.assertAlmostEqual(res_angle, exp_angle)
 
+    def test_clear_symbollayer_ids(self):
+        """
+        Test we manage to clear all symbol layer ids on a symbol
+        """
+
+        source = QgsVectorLayer("Polygon?crs=EPSG:4326", 'layer', "memory")
+        self.assertTrue(source.isValid())
+
+        layer = QgsLinePatternFillSymbolLayer()
+        fill_symbol = QgsFillSymbol([layer])
+
+        sub_renderer = QgsSingleSymbolRenderer(fill_symbol)
+        source.setRenderer(sub_renderer)
+
+        self.assertEqual(len(fill_symbol.symbolLayers()), 1)
+
+        subsymbol = fill_symbol.symbolLayers()[0].subSymbol()
+        self.assertTrue(subsymbol)
+        self.assertEqual(len(subsymbol.symbolLayers()), 1)
+
+        child_sl = subsymbol.symbolLayers()[0]
+        self.assertTrue(child_sl)
+
+        old_id = child_sl.id()
+        self.assertTrue(child_sl.id())
+
+        QgsSymbolLayerUtils.resetSymbolLayerIds(fill_symbol)
+
+        self.assertTrue(child_sl.id())
+        self.assertTrue(child_sl.id() != old_id)
+
+        QgsSymbolLayerUtils.clearSymbolLayerIds(fill_symbol)
+        self.assertFalse(child_sl.id())
+
 
 if __name__ == '__main__':
     unittest.main()