Added the necessary converter(s) for xAOD::EventAuxInfo_v2.

The converters are set up to convert _v2 objects into _v1 objects
in memory. To be able to read release 22 files, while still producing
files with the same EDM that release 21 analyses would expect.

Event/xAOD/xAODEventInfoAthenaPool/CMakeLists.txt

-################################################################################
-# Package: xAODEventInfoAthenaPool
-################################################################################
+# Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 
 # Declare the package name:
 atlas_subdir( xAODEventInfoAthenaPool )
 
-# Declare the package's dependencies:
-atlas_depends_on_subdirs( PRIVATE
-                          Database/AthenaPOOL/AthenaPoolCnvSvc
-                          Database/AthenaPOOL/AthenaPoolUtilities
-                          Event/xAOD/xAODEventInfo )
-
 # Component(s) in the package:
 atlas_add_poolcnv_library( xAODEventInfoAthenaPoolPoolCnv
-                           src/*.cxx
-                           FILES xAODEventInfo/EventInfo.h xAODEventInfo/EventAuxInfo.h xAODEventInfo/EventInfoContainer.h xAODEventInfo/EventInfoAuxContainer.h
-                           TYPES_WITH_NAMESPACE xAOD::EventInfo xAOD::EventAuxInfo xAOD::EventInfoContainer xAOD::EventInfoAuxContainer
-                           CNV_PFX xAOD
-                           LINK_LIBRARIES AthenaPoolCnvSvcLib AthenaPoolUtilities xAODEventInfo )
-
+   src/*.h src/*.cxx
+   FILES xAODEventInfo/EventInfo.h xAODEventInfo/EventAuxInfo.h
+      xAODEventInfo/EventInfoContainer.h xAODEventInfo/EventInfoAuxContainer.h
+   TYPES_WITH_NAMESPACE xAOD::EventInfo xAOD::EventAuxInfo
+      xAOD::EventInfoContainer xAOD::EventInfoAuxContainer
+   CNV_PFX xAOD
+   LINK_LIBRARIES AthenaPoolCnvSvcLib AthenaPoolUtilities AthContainers
+      xAODEventInfo )

Event/xAOD/xAODEventInfoAthenaPool/src/xAODEventAuxInfoCnv.cxx

+// Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+//
+// Dummy source file so that cmake will know that this is a custom converter.
+//

Event/xAOD/xAODEventInfoAthenaPool/src/xAODEventAuxInfoCnv.h

+// Dear emacs, this is -*- c++ -*-
+//
+// Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+//
+#ifndef XAODEVENTINFOATHENAPOOL_XAODEVENTAUXINFOCNV_H
+#define XAODEVENTINFOATHENAPOOL_XAODEVENTAUXINFOCNV_H
+
+// Local include(s).
+#include "xAODEventAuxInfoCnv_v2.h"
+
+// EDM include(s).
+#include "xAODEventInfo/EventAuxInfo.h"
+
+// Framework include(s).
+#include "AthenaPoolCnvSvc/T_AthenaPoolAuxContainerCnv.h"
+
+// Declare the POOL converter.
+typedef T_AthenaPoolAuxContainerCnv< xAOD::EventAuxInfo,
+                                     xAODEventAuxInfoCnv_v2 >
+   xAODEventAuxInfoCnv;
+
+#endif // XAODEVENTINFOATHENAPOOL_XAODEVENTAUXINFOCNV_H

Event/xAOD/xAODEventInfoAthenaPool/src/xAODEventAuxInfoCnv_v2.cxx

+// Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+
+// Local include(s).
+#include "xAODEventAuxInfoCnv_v2.h"
+
+// Core EDM include(s):
+#include "AthContainers/tools/copyAuxStoreThinned.h"
+
+// System include(s).
+#include <stdexcept>
+
+/// Convenience macro for setting the level of output messages
+#define MSGLVL MSG::INFO
+
+/// Another convenience macro for printing messages in the converter
+#define ATH_MSG( MSG )                          \
+   do {                                         \
+      if( log.level() <= MSGLVL ) {             \
+         log << MSGLVL << MSG << endmsg;        \
+      }                                         \
+   } while( 0 )
+
+void xAODEventAuxInfoCnv_v2::persToTrans( const xAOD::EventAuxInfo_v2* oldObj,
+                                          xAOD::EventAuxInfo* newObj,
+                                          MsgStream& log ) {
+
+   // Greet the user.
+   ATH_MSG( "Converting xAOD::EventAuxInfo_v2 to the current version..." );
+
+   // Copy the payload of the v2 object into the latest one by misusing
+   // the thinning code a bit...
+   SG::copyAuxStoreThinned( *oldObj, *newObj,
+                            static_cast< IThinningSvc* >( nullptr ) );
+
+   // Print what happened:
+   ATH_MSG( "Converting xAOD::EventAuxInfo_v2 to the current version... "
+            "[OK]" );
+   return;
+}
+
+void xAODEventAuxInfoCnv_v2::transToPers( const xAOD::EventAuxInfo*,
+                                          xAOD::EventAuxInfo_v2*,
+                                          MsgStream& log ) {
+
+   log << MSG::ERROR
+       << "Somebody called xAODEventAuxInfoCnv_v2::transToPers"
+       << endmsg;
+   throw std::runtime_error( "Somebody called xAODEventAuxInfoCnv_v2::"
+                             "transToPers" );
+   return;
+}

Event/xAOD/xAODEventInfoAthenaPool/src/xAODEventAuxInfoCnv_v2.h

+// Dear emacs, this is -*- c++ -*-
+//
+// Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+//
+#ifndef XAODEVENTINFOATHENAPOOL_XAODEVENAUXINFOCNV_V2_H
+#define XAODEVENTINFOATHENAPOOL_XAODEVENAUXINFOCNV_V2_H
+
+// Gaudi/Athena include(s).
+#include "AthenaPoolCnvSvc/T_AthenaPoolTPConverter.h"
+
+// EDM include(s).
+#include "xAODEventInfo/versions/EventAuxInfo_v2.h"
+#include "xAODEventInfo/EventAuxInfo.h"
+
+/// Converter for reading @c xAOD::EventAuxInfo_v2
+///
+/// This converter takes care of reading @c xAOD::EventAuxInfo_v2 into
+/// the "current" version of @c xAOD::EventAuxInfo. (Which is
+/// @c xAOD::EventAuxInfo_v1 in this branch.)
+///
+/// @author Attila Krasznahorkay <Attila.Krasznahorkay@cern.ch>
+///
+class xAODEventAuxInfoCnv_v2 :
+   public T_AthenaPoolTPCnvBase< xAOD::EventAuxInfo,
+                                 xAOD::EventAuxInfo_v2 > {
+
+public:
+   /// Default constructor
+   xAODEventAuxInfoCnv_v2() = default;
+
+   /// Function converting from the old type to the current one
+   virtual void persToTrans( const xAOD::EventAuxInfo_v2* oldObj,
+                             xAOD::EventAuxInfo* newObj,
+                             MsgStream& log ) override;
+   /// Dummy function inherited from the base class
+   virtual void transToPers( const xAOD::EventAuxInfo*,
+                             xAOD::EventAuxInfo_v2*,
+                             MsgStream& log ) override;
+
+}; // class xAODEventAuxInfoCnv_v2
+
+#endif // XAODEVENTINFOATHENAPOOL_XAODEVENAUXINFOCNV_V2_H

Event/xAOD/xAODEventInfoAthenaPool/src/xAODEventInfoAthenaPoolTPCnv.cxx

+// Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+
+// Gaudi/Athena include(s).
+#include "AthenaKernel/TPCnvFactory.h"
+
+// EDM include(s).
+#include "xAODEventInfo/EventAuxInfo.h"
+#include "xAODEventInfo/versions/EventAuxInfo_v2.h"
+
+// Local include(s).
+#include "xAODEventAuxInfoCnv_v2.h"
+
+// Declare the T/P converter(s).
+DECLARE_TPCNV_FACTORY( xAODEventAuxInfoCnv_v2,
+                       xAOD::EventAuxInfo,
+                       xAOD::EventAuxInfo_v2,
+                       Athena::TPCnvVers::Old )