Fix for failing dataflow build (#13721)

(cherry picked from commit 7f54d8f)

Author: jackal1-66

Generators/CMakeLists.txt

@@ -24,8 +24,6 @@ o2_add_library(Generators
                        src/GeneratorTGenerator.cxx
                        src/GeneratorExternalParam.cxx
                        src/GeneratorFromFile.cxx
-                       src/GeneratorHybrid.cxx
-                       src/GeneratorHybridParam.cxx
                        src/GeneratorFromO2KineParam.cxx
                        src/GeneratorFileOrCmd.cxx
                        src/GeneratorFileOrCmdParam.cxx
@@ -49,6 +47,8 @@ o2_add_library(Generators
                        $<$<BOOL:${HepMC3_FOUND}>:src/GeneratorHepMC.cxx>
                        $<$<BOOL:${HepMC3_FOUND}>:src/GeneratorHepMCParam.cxx>
                        $<$<BOOL:${HepMC3_FOUND}>:src/AODToHepMC.cxx>
+                       $<$<AND:$<BOOL:${pythia_FOUND}>,$<BOOL:${HepMC3_FOUND}>>:src/GeneratorHybrid.cxx>
+                       $<$<AND:$<BOOL:${pythia_FOUND}>,$<BOOL:${HepMC3_FOUND}>>:src/GeneratorHybridParam.cxx>
                PUBLIC_LINK_LIBRARIES FairRoot::Base O2::SimConfig O2::CommonUtils O2::DetectorsBase O2::ZDCBase
                                      O2::SimulationDataFormat ${pythiaTarget} ${hepmcTarget}
                                      FairRoot::Gen
@@ -69,8 +69,6 @@ set(headers
     include/Generators/GeneratorTGenerator.h
     include/Generators/GeneratorExternalParam.h
     include/Generators/GeneratorFromFile.h
-    include/Generators/GeneratorHybrid.h
-    include/Generators/GeneratorHybridParam.h
     include/Generators/GeneratorFromO2KineParam.h
     include/Generators/GeneratorFileOrCmd.h
     include/Generators/GeneratorFileOrCmdParam.h
@@ -102,6 +100,11 @@ if(HepMC3_FOUND)
   list(APPEND headers include/Generators/GeneratorHepMCParam.h)
 endif()
 
+if(pythia_FOUND AND HepMC3_FOUND)
+  list(APPEND headers include/Generators/GeneratorHybrid.h)
+  list(APPEND headers include/Generators/GeneratorHybridParam.h)
+endif()
+
 o2_target_root_dictionary(Generators HEADERS ${headers})
 
 o2_add_test_root_macro(share/external/extgen.C

Generators/src/GeneratorFactory.cxx

@@ -18,7 +18,6 @@
 #include <fairlogger/Logger.h>
 #include <SimConfig/SimConfig.h>
 #include <Generators/GeneratorFromFile.h>
-#include <Generators/GeneratorHybrid.h>
 #include <Generators/GeneratorTParticle.h>
 #include <Generators/GeneratorTParticleParam.h>
 #ifdef GENERATORS_WITH_PYTHIA8
@@ -27,12 +26,15 @@
 #endif
 #include <Generators/GeneratorTGenerator.h>
 #include <Generators/GeneratorExternalParam.h>
-#include <Generators/GeneratorHybridParam.h>
 #include "Generators/GeneratorFromO2KineParam.h"
 #ifdef GENERATORS_WITH_HEPMC3
 #include <Generators/GeneratorHepMC.h>
 #include <Generators/GeneratorHepMCParam.h>
 #endif
+#if defined(GENERATORS_WITH_PYTHIA8) && defined(GENERATORS_WITH_HEPMC3)
+#include <Generators/GeneratorHybrid.h>
+#include <Generators/GeneratorHybridParam.h>
+#endif
 #include <Generators/PrimaryGenerator.h>
 #include <Generators/BoxGunParam.h>
 #include <Generators/TriggerParticle.h>
@@ -260,6 +262,7 @@ void GeneratorFactory::setPrimaryGenerator(o2::conf::SimConfig const& conf, Fair
         primGen->AddGenerator(boxGen);
       }
     }
+#if defined(GENERATORS_WITH_PYTHIA8) && defined(GENERATORS_WITH_HEPMC3)
   } else if (genconfig.compare("hybrid") == 0) { // hybrid using multiple generators
     LOG(info) << "Init hybrid generator";
     auto& hybridparam = GeneratorHybridParam::Instance();
@@ -276,6 +279,7 @@ void GeneratorFactory::setPrimaryGenerator(o2::conf::SimConfig const& conf, Fair
     }
     auto hybrid = new o2::eventgen::GeneratorHybrid(config);
     primGen->AddGenerator(hybrid);
+#endif
   } else {
     LOG(fatal) << "Invalid generator";
   }

Generators/src/GeneratorsLinkDef.h

@@ -52,10 +52,12 @@
 #pragma link C++ class o2::conf::ConfigurableParamHelper < o2::eventgen::DecayerPythia8Param> + ;
 #pragma link C++ class o2::eventgen::GeneratorFactory + ;
 #endif
-#pragma link C++ class o2::eventgen::GeneratorFromFile + ;
-#pragma link C++ class o2::eventgen::GeneratorFromO2Kine + ;
+#if defined(GENERATORS_WITH_PYTHIA8) && defined(GENERATORS_WITH_HEPMC3)
 #pragma link C++ class o2::eventgen::GeneratorHybrid + ;
 #pragma link C++ class o2::eventgen::GeneratorHybridParam + ;
+#endif
+#pragma link C++ class o2::eventgen::GeneratorFromFile + ;
+#pragma link C++ class o2::eventgen::GeneratorFromO2Kine + ;
 #pragma link C++ class o2::eventgen::GeneratorFromO2KineParam + ;
 #pragma link C++ class o2::eventgen::O2KineGenConfig + ;
 #pragma link C++ class o2::conf::ConfigurableParamHelper < o2::eventgen::GeneratorFromO2KineParam> + ;