Followup 9508f8b, fix other potential crashes

Author: nyalldawson

src/app/qgsattributetabledialog.cpp

@@ -364,7 +364,7 @@ void QgsAttributeTableDialog::runFieldCalculation( QgsVectorLayer* layer, QStrin
 
   int rownum = 1;
 
-  const QgsField &fld = layer->fields()[ fieldindex ];
+  QgsField fld = layer->fields()[ fieldindex ];
 
   //go through all the features and change the new attributes
   QgsFeatureIterator fit = layer->getFeatures( request );

src/app/qgsfieldcalculator.cpp

@@ -235,7 +235,7 @@ void QgsFieldCalculator::accept()
     bool useGeometry = exp.needsGeometry();
     int rownum = 1;
 
-    const QgsField& field = mVectorLayer->fields()[mAttributeId];
+    QgsField field = mVectorLayer->fields()[mAttributeId];
 
     bool newField = !mUpdateExistingGroupBox->isChecked();
     QVariant emptyAttribute;

src/app/qgsidentifyresultsdialog.cpp

@@ -1455,7 +1455,7 @@ void QgsIdentifyResultsDialog::attributeValueChanged( QgsFeatureId fid, int idx,
   if ( idx >= vlayer->fields().size() )
     return;
 
-  const QgsField &fld = vlayer->fields().at( idx );
+  QgsField fld = vlayer->fields().at( idx );
 
   for ( int i = 0; i < layItem->childCount(); i++ )
   {

src/gui/attributetable/qgsattributetablemodel.cpp

@@ -526,7 +526,7 @@ QVariant QgsAttributeTableModel::data( const QModelIndex &index, int role ) cons
   if ( role == FieldIndexRole )
     return fieldId;
 
-  const QgsField& field = layer()->fields().at( fieldId );
+  QgsField field = layer()->fields().at( fieldId );
 
   QVariant::Type fldType = field.type();
   bool fldNumeric = ( fldType == QVariant::Int || fldType == QVariant::Double || fldType == QVariant::LongLong );

src/gui/editorwidgets/core/qgseditorwidgetfactory.cpp

@@ -66,8 +66,7 @@ QString QgsEditorWidgetFactory::representValue( QgsVectorLayer* vl, int fieldIdx
   Q_UNUSED( cache )
   Q_UNUSED( value )
 
-  const QgsField &fld = vl->fields().at( fieldIdx );
-  return fld.displayString( value );
+  return vl->fields().at( fieldIdx ).displayString( value );
 }
 
 QVariant QgsEditorWidgetFactory::createCache( QgsVectorLayer* vl, int fieldIdx, const QgsEditorWidgetConfig& config )