Allow access to feature geometry in generator subsymbols via

geometry($currentfeature)

When used in a geometry generator subsymbol, the expression

    geometry($currentfeature)

should refer to the original feature's geometry, not the geometry
generated by the generator symbol (which is accessible through
$geometry)

Fixes #46455

src/core/symbology/qgsgeometrygeneratorsymbollayer.cpp

@@ -305,7 +305,7 @@ bool QgsGeometryGeneratorSymbolLayer::isCompatibleWithSymbol( QgsSymbol *symbol
   return true;
 }
 
-QgsGeometry QgsGeometryGeneratorSymbolLayer::evaluateGeometryInPainterUnits( const QgsGeometry &input, const QgsFeature &feature, const QgsRenderContext &renderContext, QgsExpressionContext &expressionContext ) const
+QgsGeometry QgsGeometryGeneratorSymbolLayer::evaluateGeometryInPainterUnits( const QgsGeometry &input, const QgsFeature &, const QgsRenderContext &renderContext, QgsExpressionContext &expressionContext ) const
 {
   QgsGeometry drawGeometry( input );
   // step 1 - scale the draw geometry from PAINTER units to target units (e.g. millimeters)
@@ -314,11 +314,9 @@ QgsGeometry QgsGeometryGeneratorSymbolLayer::evaluateGeometryInPainterUnits( con
   drawGeometry.transform( painterToTargetUnits );
 
   // step 2 - set the feature to use the new scaled geometry, and inject it into the expression context
-  QgsFeature f( feature );
-  f.setGeometry( drawGeometry );
   QgsExpressionContextScope *generatorScope = new QgsExpressionContextScope();
   QgsExpressionContextScopePopper popper( expressionContext, generatorScope );
-  generatorScope->setFeature( f );
+  generatorScope->setGeometry( drawGeometry );
 
   // step 3 - evaluate the new generated geometry.
   QgsGeometry geom = mExpression->evaluate( &expressionContext ).value<QgsGeometry>();
@@ -483,8 +481,8 @@ void QgsGeometryGeneratorSymbolLayer::render( QgsSymbolRenderContext &context, Q
   }
 
   QgsExpressionContextScope *subSymbolExpressionContextScope = mSymbol->symbolRenderContext()->expressionContextScope();
-
-  subSymbolExpressionContextScope->setFeature( f );
+  // override the $geometry value for all subsymbols -- this should be the generated geometry
+  subSymbolExpressionContextScope->setGeometry( f.geometry() );
 
   const bool prevIsSubsymbol = context.renderContext().flags() & Qgis::RenderContextFlag::RenderingSubSymbol;
   context.renderContext().setFlag( Qgis::RenderContextFlag::RenderingSubSymbol );

tests/src/python/test_qgsgeometrygeneratorsymbollayer.py

@@ -47,7 +47,11 @@ from qgis.core import (
     QgsCoordinateTransform,
     QgsArrowSymbolLayer,
     QgsFeature,
-    QgsGeometry
+    QgsGeometry,
+    QgsFontMarkerSymbolLayer,
+    QgsFontUtils,
+    QgsSymbolLayer,
+    QgsProperty
 )
 
 from qgis.testing import start_app, unittest
@@ -410,6 +414,78 @@ class TestQgsGeometryGeneratorSymbolLayerV2(unittest.TestCase):
         self.report += renderchecker.report()
         self.assertTrue(res)
 
+    def test_geometry_function(self):
+        """
+        The $geometry function used in a subsymbol should refer to the generated geometry
+        """
+        points = QgsVectorLayer('Point?crs=epsg:4326', 'Points', 'memory')
+        self.assertTrue(points.isValid())
+        f = QgsFeature()
+        f.setGeometry(QgsGeometry.fromWkt('Point(1 2)'))
+        points.dataProvider().addFeature(f)
+
+        font = QgsFontUtils.getStandardTestFont('Bold')
+        font_marker = QgsFontMarkerSymbolLayer(font.family(), 'x', 16)
+        font_marker.setDataDefinedProperty(QgsSymbolLayer.PropertyCharacter, QgsProperty.fromExpression('geom_to_wkt($geometry)'))
+        subsymbol = QgsMarkerSymbol()
+        subsymbol.changeSymbolLayer(0, font_marker)
+
+        parent_generator = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'translate($geometry, 1, 2)'})
+        parent_generator.setSymbolType(QgsSymbol.Marker)
+
+        parent_generator.setSubSymbol(subsymbol)
+
+        geom_symbol = QgsMarkerSymbol()
+        geom_symbol.changeSymbolLayer(0, parent_generator)
+        points.renderer().setSymbol(geom_symbol)
+
+        mapsettings = QgsMapSettings(self.mapsettings)
+        mapsettings.setExtent(QgsRectangle(0, 0, 5, 5))
+        mapsettings.setLayers([points])
+
+        renderchecker = QgsMultiRenderChecker()
+        renderchecker.setMapSettings(mapsettings)
+        renderchecker.setControlName('expected_geometrygenerator_function_geometry')
+        res = renderchecker.runTest('geometrygenerator_function_geometry')
+        self.report += renderchecker.report()
+        self.assertTrue(res)
+
+    def test_feature_geometry(self):
+        """
+        The geometry($currentfeature) expression used in a subsymbol should refer to the original FEATURE geometry
+        """
+        points = QgsVectorLayer('Point?crs=epsg:4326', 'Points', 'memory')
+        self.assertTrue(points.isValid())
+        f = QgsFeature()
+        f.setGeometry(QgsGeometry.fromWkt('Point(1 2)'))
+        points.dataProvider().addFeature(f)
+
+        font = QgsFontUtils.getStandardTestFont('Bold')
+        font_marker = QgsFontMarkerSymbolLayer(font.family(), 'x', 16)
+        font_marker.setDataDefinedProperty(QgsSymbolLayer.PropertyCharacter, QgsProperty.fromExpression('geom_to_wkt(geometry($currentfeature))'))
+        subsymbol = QgsMarkerSymbol()
+        subsymbol.changeSymbolLayer(0, font_marker)
+
+        parent_generator = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'translate($geometry, 1, 2)'})
+        parent_generator.setSymbolType(QgsSymbol.Marker)
+
+        parent_generator.setSubSymbol(subsymbol)
+
+        geom_symbol = QgsMarkerSymbol()
+        geom_symbol.changeSymbolLayer(0, parent_generator)
+        points.renderer().setSymbol(geom_symbol)
+
+        mapsettings = QgsMapSettings(self.mapsettings)
+        mapsettings.setExtent(QgsRectangle(0, 0, 5, 5))
+        mapsettings.setLayers([points])
+
+        renderchecker = QgsMultiRenderChecker()
+        renderchecker.setMapSettings(mapsettings)
+        renderchecker.setControlName('expected_geometrygenerator_feature_geometry')
+        res = renderchecker.runTest('geometrygenerator_feature_geometry')
+        self.report += renderchecker.report()
+        self.assertTrue(res)
+
     def imageCheck(self, name, reference_image, image):
         self.report += "<h2>Render {}</h2>\n".format(name)
         temp_dir = QDir.tempPath() + '/'