QgsAbstractVectorLayerLabeling *QgsAfsProvider::createLabeling( const QVariantMap & ) const
{
  std::unique_ptr< QgsAbstractVectorLayerLabeling > labeling = QgsArcGisRestUtils::parseEsriLabeling( mLabelingDataList );
  return labeling.release();
}

---

In file included from /usr/include/c++/8/memory:80,
                 from /home/webmaster/dev/cpp/QGIS/src/providers/arcgisrest/qgsafsprovider.h:21,
                 from /home/webmaster/dev/cpp/QGIS/src/providers/arcgisrest/qgsafsprovider.cpp:18:
/usr/include/c++/8/bits/unique_ptr.h: In instantiation of ‘void std::default_delete<_Tp>::operator()(_Tp*) const [with _Tp = QgsAbstractVectorLayerLabeling]’:
/usr/include/c++/8/bits/unique_ptr.h:274:17:   required from ‘std::unique_ptr<_Tp, _Dp>::~unique_ptr() [with _Tp = QgsAbstractVectorLayerLabeling; _Dp = std::default_delete<QgsAbstractVectorLayerLabeling>]’
/home/webmaster/dev/cpp/QGIS/src/providers/arcgisrest/qgsafsprovider.cpp:317:121:   required from here
/usr/include/c++/8/bits/unique_ptr.h:79:16: error: invalid application of ‘sizeof’ to incomplete type ‘QgsAbstractVectorLayerLabeling’
  static_assert(sizeof(_Tp)>0,
                ^~~~~~~~~~~
make[2]: *** [src/providers/arcgisrest/CMakeFiles/arcgisfeatureserverprovider.dir/build.make:126: src/providers/arcgisrest/CMakeFiles/arcgisfeatureserverprovider.dir/qgsafsprovider.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:1962: src/providers/arcgisrest/CMakeFiles/arcgisfeatureserverprovider.dir/all] Error 2