[processing] Fix feedback message in merge vector alg

Author: nyalldawson

src/analysis/processing/qgsalgorithmmergevector.cpp

@@ -186,16 +186,18 @@ QVariantMap QgsMergeVectorAlgorithm::processAlgorithm( const QVariantMap &parame
   bool isMulti = QgsWkbTypes::isMultiType( outputType );
   double step = totalFeatureCount > 0 ? 100.0 / totalFeatureCount : 1;
   i = 0;
+  int layerNumber = 0;
   for ( QgsMapLayer *layer : layers )
   {
+    layerNumber++;
     if ( !layer )
       continue;
 
     QgsVectorLayer *vl = qobject_cast< QgsVectorLayer * >( layer );
     if ( !vl )
       continue;
 
-    feedback->pushInfo( QObject::tr( "Packaging layer %1/%2: %3" ).arg( i ).arg( layers.count() ).arg( layer->name() ) );
+    feedback->pushInfo( QObject::tr( "Packaging layer %1/%2: %3" ).arg( layerNumber ).arg( layers.count() ).arg( layer->name() ) );
 
     QgsFeatureIterator it = vl->getFeatures( QgsFeatureRequest().setDestinationCrs( outputCrs, context.transformContext() ) );
     QgsFeature f;