diff --git a/Event/xAOD/xAODEventInfoCnv/cmt/requirements b/Event/xAOD/xAODEventInfoCnv/cmt/requirements
deleted file mode 100644
index 7e236e7a942b1112766deacf45b8a1ac68786f5d..0000000000000000000000000000000000000000
--- a/Event/xAOD/xAODEventInfoCnv/cmt/requirements
+++ /dev/null
@@ -1,40 +0,0 @@
-package xAODEventInfoCnv
-# $Id: requirements 769747 2016-08-24 08:07:58Z will $
-
-author Attila Krasznahorkay
-
-public
-
-use AtlasPolicy AtlasPolicy-*
-
-use xAODCnvInterfaces xAODCnvInterfaces-* Event/xAOD
-
-private
-
-use GaudiInterface GaudiInterface-* External
-
-use AthenaBaseComps AthenaBaseComps-* Control
-use AthenaKernel AthenaKernel-* Control
-
-use AthenaPoolUtilities AthenaPoolUtilities-* Database/AthenaPOOL
-
-#use InDetBeamSpotService InDetBeamSpotService-* InnerDetector/InDetConditions
-use_ifndef pplist="XAOD_ANALYSIS" pkg="InnerDetector/InDetConditions/InDetBeamSpotService"
-#use LumiBlockComps LumiBlockComps-* LumiBlock
-use_ifndef pplist="XAOD_ANALYSIS" pkg="LumiBlock/LumiBlockComps"
-
-use xAODEventInfo xAODEventInfo-* Event/xAOD
-use EventInfo EventInfo-* Event
-
-use xAODTruth xAODTruth-* Event/xAOD
-
-
-end_private
-
-# Declare the library:
-library xAODEventInfoCnv *.cxx components/*.cxx
-apply_pattern component_library
-
-# Install the additional files:
-apply_pattern declare_python_modules files="*.py"
-apply_pattern declare_joboptions files="*.py"
diff --git a/Event/xAOD/xAODEventInfoCnv/share/xAODEventInfoNonConstCnv_jobOptions.py b/Event/xAOD/xAODEventInfoCnv/share/xAODEventInfoNonConstCnv_jobOptions.py
new file mode 100644
index 0000000000000000000000000000000000000000..d6facddef0263843e9963acd442162da4176b38c
--- /dev/null
+++ b/Event/xAOD/xAODEventInfoCnv/share/xAODEventInfoNonConstCnv_jobOptions.py
@@ -0,0 +1,27 @@
+#
+# Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
+#
+
+# Set up the reading of a file.
+FNAME = '/cvmfs/atlas-nightlies.cern.ch/repo/data/data-art/CommonInputs/DAOD_PHYSVAL/mc16_13TeV.410501.PowhegPythia8EvtGen_A14_ttbar_hdamp258p75_nonallhad.DAOD_PHYSVAL.e5458_s3126_r9364_r9315_AthDerivation-21.2.1.0.root'
+import AthenaPoolCnvSvc.ReadAthenaPool
+ServiceMgr.EventSelector.InputCollections = [ FNAME ]
+
+# Access the algorithm sequence.
+from AthenaCommon.AlgSequence import AlgSequence
+theJob = AlgSequence()
+
+# Set up the algorithm making the xAOD::EventInfo object non-const.
+from AthenaCommon import CfgMgr
+theJob += CfgMgr.xAODMaker__EventInfoNonConstCnvAlg( 'EventInfoNonConstCnvAlg',
+ OutputLevel = VERBOSE )
+
+# Set up the algorithm that tries to now modify the object.
+theJob += CfgMgr.xAODReader__EventInfoModifierAlg( 'EventInfoModifierAlg',
+ OutputLevel = VERBOSE )
+
+# Tweak the job a bit more.
+from AthenaCommon.AppMgr import theApp
+theApp.EvtMax = 10
+ServiceMgr.MessageSvc.OutputLevel = INFO
+ServiceMgr.MessageSvc.defaultLimit = 1000000
diff --git a/Event/xAOD/xAODEventInfoCnv/src/EventInfoModifierAlg.cxx b/Event/xAOD/xAODEventInfoCnv/src/EventInfoModifierAlg.cxx
new file mode 100644
index 0000000000000000000000000000000000000000..114b18dc543c07c429b13b3d040c3844f67e2768
--- /dev/null
+++ b/Event/xAOD/xAODEventInfoCnv/src/EventInfoModifierAlg.cxx
@@ -0,0 +1,44 @@
+//
+// Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
+//
+
+// Local include(s).
+#include "EventInfoModifierAlg.h"
+
+// EDM include(s).
+#include "xAODEventInfo/EventInfo.h"
+
+namespace xAODReader {
+
+ EventInfoModifierAlg::EventInfoModifierAlg( const std::string& name,
+ ISvcLocator* svcLoc )
+ : AthAlgorithm( name, svcLoc ) {
+
+ // Declare the algorithm's properties.
+ declareProperty( "EventInfoKey", m_key = "EventInfo",
+ "Event store key for the xAOD::EventInfo object to "
+ "modify" );
+ }
+
+ StatusCode EventInfoModifierAlg::execute() {
+
+ // Retrieve a non-const pointer to the event info.
+ xAOD::EventInfo* ei = nullptr;
+ ATH_CHECK( evtStore()->retrieve( ei, m_key ) );
+ ATH_MSG_VERBOSE( "Retrieved a non-const xAOD::EventInfo object "
+ "with key \"" << m_key << "\"" );
+
+ // Now try to modify the object.
+ ei->setRunNumber( ei->runNumber() + 1 );
+ ei->setEventNumber( ei->eventNumber() - 1 );
+ if( ei->isAvailable< uint32_t >( "mvEventNumber" ) ) {
+ ei->setMCEventNumber( ei->mcEventNumber() + 2 );
+ }
+ ATH_MSG_VERBOSE( "Modified some static and dynamic properties of \""
+ << m_key << "\"" );
+
+ // Return gracefully.
+ return StatusCode::SUCCESS;
+ }
+
+} // namespace xAODReader
diff --git a/Event/xAOD/xAODEventInfoCnv/src/EventInfoModifierAlg.h b/Event/xAOD/xAODEventInfoCnv/src/EventInfoModifierAlg.h
new file mode 100644
index 0000000000000000000000000000000000000000..9168d7a299f2bc57721c5e80332b215ac899086c
--- /dev/null
+++ b/Event/xAOD/xAODEventInfoCnv/src/EventInfoModifierAlg.h
@@ -0,0 +1,40 @@
+// Dear emacs, this is -*- c++ -*-
+//
+// Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
+//
+#ifndef XAODEVENTINFOCNV_EVENTINFOMODIFIERALG_H
+#define XAODEVENTINFOCNV_EVENTINFOMODIFIERALG_H
+
+// System include(s).
+#include <string>
+
+// Gaudi/Athena include(s).
+#include "AthenaBaseComps/AthAlgorithm.h"
+
+namespace xAODReader {
+
+ /// Algorithm making modifications to a non-const @c xAOD::EventInfo
+ ///
+ /// This algorithm is here to allow for some tests that modify an
+ /// @c xAOD::EventInfo object. That was created some "some way".
+ ///
+ /// @author Attila Krasznahorkay <Attila.Krasznahorkay@cern.ch>
+ ///
+ class EventInfoModifierAlg final : public AthAlgorithm {
+
+ public:
+ /// Algorithm constructor
+ EventInfoModifierAlg( const std::string& name, ISvcLocator* svcLoc );
+
+ /// Function executing the algorithm
+ virtual StatusCode execute() override;
+
+ private:
+ /// Key for the xAOD::EventInfo object
+ std::string m_key;
+
+ }; // class EventInfoModifierAlg
+
+} // namespace xAODReader
+
+#endif // XAODEVENTINFOCNV_EVENTINFOMODIFIERALG_H
diff --git a/Event/xAOD/xAODEventInfoCnv/src/EventInfoNonConstCnvAlg.cxx b/Event/xAOD/xAODEventInfoCnv/src/EventInfoNonConstCnvAlg.cxx
new file mode 100644
index 0000000000000000000000000000000000000000..1f65fe1702bc7735c2049ff17f1e1853a05375c4
--- /dev/null
+++ b/Event/xAOD/xAODEventInfoCnv/src/EventInfoNonConstCnvAlg.cxx
@@ -0,0 +1,72 @@
+//
+// Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
+//
+
+// Local include(s).
+#include "EventInfoNonConstCnvAlg.h"
+
+// EDM include(s).
+#include "xAODEventInfo/EventInfo.h"
+#include "xAODEventInfo/EventAuxInfo.h"
+
+// System include(s).
+#include <memory>
+
+namespace xAODMaker {
+
+ EventInfoNonConstCnvAlg::EventInfoNonConstCnvAlg( const std::string& name,
+ ISvcLocator* svcLoc )
+ : AthAlgorithm( name, svcLoc ) {
+
+ // Declare the algorithm's properties.
+ declareProperty( "EventInfoKey", m_key = "EventInfo",
+ "Event store key for the xAOD::EventInfo object to "
+ "modify" );
+ }
+
+ StatusCode EventInfoNonConstCnvAlg::execute() {
+
+ // Check if xAOD::EventInfo is available.
+ if( ! evtStore()->contains< xAOD::EventInfo >( m_key ) ) {
+ // If not, then let's just stop right away.
+ ATH_MSG_VERBOSE( "No xAOD::EventInfo with key \"" << m_key << "\"" );
+ return StatusCode::SUCCESS;
+ }
+
+ // Retrieve the const object.
+ const xAOD::EventInfo* ei = nullptr;
+ ATH_CHECK( evtStore()->retrieve( ei, m_key ) );
+
+ // Check if it's already set up to be modifiable.
+ if( ei->getStore() ) {
+ // If so, let's assume that SG will also let the object be retrieved
+ // as a non-const pointer.
+ ATH_MSG_VERBOSE( "xAOD::EventInfo with key \"" << m_key
+ << "\" seems to be modifiable -> not touching it" );
+ return StatusCode::SUCCESS;
+ }
+
+ // Access the aux container as well now.
+ const xAOD::EventAuxInfo* aux = nullptr;
+ ATH_CHECK( evtStore()->retrieve( aux, m_key + "Aux." ) );
+
+ // Make a deep copy of the object.
+ auto newei = std::make_unique< xAOD::EventInfo >();
+ auto newaux = std::make_unique< xAOD::EventAuxInfo >();
+ newei->setStore( newaux.get() );
+ *newei = *ei;
+ ATH_MSG_VERBOSE( "Made a deep copy of \"" << m_key << "\"" );
+
+ // Overwrite the original object with its deep copy.
+ static const bool ALLOW_MODS = true;
+ ATH_CHECK( evtStore()->overwrite( std::move( newei ), m_key,
+ ALLOW_MODS ) );
+ ATH_CHECK( evtStore()->overwrite( std::move( newaux ), m_key + "Aux.",
+ ALLOW_MODS ) );
+ ATH_MSG_VERBOSE( "Overwrote \"" << m_key << "\" with its deep copy" );
+
+ // Return gracefully.
+ return StatusCode::SUCCESS;
+ }
+
+} // namespace xAODMaker
diff --git a/Event/xAOD/xAODEventInfoCnv/src/EventInfoNonConstCnvAlg.h b/Event/xAOD/xAODEventInfoCnv/src/EventInfoNonConstCnvAlg.h
new file mode 100644
index 0000000000000000000000000000000000000000..a5c292bbfe2f1b6c901e6555feea5bc471ac61ab
--- /dev/null
+++ b/Event/xAOD/xAODEventInfoCnv/src/EventInfoNonConstCnvAlg.h
@@ -0,0 +1,48 @@
+// Dear emacs, this is -*- c++ -*-
+//
+// Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
+//
+#ifndef XAODEVENTINFOCNV_EVENTINFONONCONSTCNVALG_H
+#define XAODEVENTINFOCNV_EVENTINFONONCONSTCNVALG_H
+
+// System include(s).
+#include <string>
+
+// Gaudi/Athena include(s).
+#include "AthenaBaseComps/AthAlgorithm.h"
+
+namespace xAODMaker {
+
+ /// Algorithm making a const @c xAOD::EventInfo object non-const
+ ///
+ /// In jobs that process an input file which already has an
+ /// @c xAOD::EventInfo object in it, which itself has information that we
+ /// need to keep, but the job wants to further modify that object, we need
+ /// to make sure that algorithms are able to do those modifications.
+ ///
+ /// This algorithm can be used to make the @c xAOD::EventInfo object in
+ /// StoreGate modifiable.
+ ///
+ /// Note that this implementation is *only* meant for 21.X. For release
+ /// 22.X we will take care of this a bit differently.
+ ///
+ /// @author Attila Krasznahorkay <Attila.Krasznahorkay@cern.ch>
+ ///
+ class EventInfoNonConstCnvAlg final : public AthAlgorithm {
+
+ public:
+ /// Algorithm constructor
+ EventInfoNonConstCnvAlg( const std::string& name, ISvcLocator* svcLoc );
+
+ /// Function executing the algorithm
+ virtual StatusCode execute() override;
+
+ private:
+ /// Key for the xAOD::EventInfo object
+ std::string m_key;
+
+ }; // class EventInfoNonConstCnvAlg
+
+} // namespace xAODMaker
+
+#endif // XAODEVENTINFOCNV_EVENTINFONONCONSTCNVALG_H
diff --git a/Event/xAOD/xAODEventInfoCnv/src/components/xAODEventInfoCnv_entries.cxx b/Event/xAOD/xAODEventInfoCnv/src/components/xAODEventInfoCnv_entries.cxx
index aadcfe84b7b923f3a9260dfd93896346eeabbda8..6af48e19f67f8eff5ab0c70e1db36eec57427d1b 100644
--- a/Event/xAOD/xAODEventInfoCnv/src/components/xAODEventInfoCnv_entries.cxx
+++ b/Event/xAOD/xAODEventInfoCnv/src/components/xAODEventInfoCnv_entries.cxx
@@ -1,4 +1,6 @@
-// $Id: xAODEventInfoCnv_entries.cxx 769747 2016-08-24 08:07:58Z will $
+//
+// Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
+//
// Gaudi/Athena include(s):
#include "GaudiKernel/DeclareFactoryEntries.h"
@@ -9,6 +11,8 @@
#include "../EventInfoCnvAlg.h"
#include "../EventInfoReaderAlg.h"
#include "../EventDuplicateFinderAlg.h"
+#include "../EventInfoNonConstCnvAlg.h"
+#include "../EventInfoModifierAlg.h"
#include "../EventInfoMCWeightFixAlg.h"
@@ -17,6 +21,8 @@ DECLARE_NAMESPACE_TOOL_FACTORY( xAODMaker, EventInfoSelectorTool )
DECLARE_NAMESPACE_ALGORITHM_FACTORY( xAODMaker, EventInfoCnvAlg )
DECLARE_NAMESPACE_ALGORITHM_FACTORY( xAODReader, EventInfoReaderAlg )
DECLARE_NAMESPACE_ALGORITHM_FACTORY( xAODReader, EventDuplicateFinderAlg )
+DECLARE_NAMESPACE_ALGORITHM_FACTORY( xAODMaker, EventInfoNonConstCnvAlg )
+DECLARE_NAMESPACE_ALGORITHM_FACTORY( xAODReader, EventInfoModifierAlg )
DECLARE_ALGORITHM_FACTORY( EventInfoMCWeightFixAlg )
@@ -27,6 +33,8 @@ DECLARE_FACTORY_ENTRIES( xAODEventInfoCnv ) {
DECLARE_NAMESPACE_ALGORITHM( xAODMaker, EventInfoCnvAlg )
DECLARE_NAMESPACE_ALGORITHM( xAODReader, EventInfoReaderAlg )
DECLARE_NAMESPACE_ALGORITHM( xAODReader, EventDuplicateFinderAlg )
+ DECLARE_NAMESPACE_ALGORITHM( xAODMaker, EventInfoNonConstCnvAlg )
+ DECLARE_NAMESPACE_ALGORITHM( xAODReader, EventInfoModifierAlg )
DECLARE_ALGORITHM( EventInfoMCWeightFixAlg )