Build errors with GEANT4 11.2.0

[smuzaffar]

Hi,
Looks like celeritas v0.4.1 or latest devel branch failed to build with Geant 11.2.0. The build error I get is [a]

In file included from <path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4TouchableHandle.hh:42,
                 from <path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4StepPoint.hh:47,
                 from <path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4Step.hh:53,
                 from <path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4VParticleChange.hh:65,
                 from <path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4VProcess.hh:48,
                 from <path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4Transportation.hh:46,
                 from <path>/celeritas/src/celeritas/ext/GeantGeoParams.cc:14:
<path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4VTouchable.hh:39:7: error: conflicting declaration 'using G4VTouchable = class G4TouchableHistory'
   39 | using G4VTouchable = G4TouchableHistory;
      |       ^~~~~~~~~~~~
In file included from <path>/celeritas/src/celeritas/ext/GeantGeoData.hh:18,
                 from <path>/celeritas/src/celeritas/ext/GeantGeoParams.hh:19,
                 from <path>/celeritas/src/celeritas/ext/GeantGeoParams.cc:8:
<path>/celeritas/src/celeritas/ext/detail/GeantGeoNavCollection.hh:20:7: note: previous declaration as 'class G4VTouchable'
   20 | class G4VTouchable;
      |       ^~~~~~~~~~~~
In file included from <path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4StepPoint.hh:191:
<path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4StepPoint.icc: In member function 'G4VPhysicalVolume* G4StepPoint::GetPhysicalVolume() const':
<path>/geant4/11.2.0-369aba6a4851f900c7e85d3309525223/include/Geant4/G4StepPoint.icc:158:21: error: invalid use of incomplete type 'class G4VTouchable'
  158 |   return fpTouchable->GetVolume();
      |                     ^~
<path>/celeritas/src/celeritas/ext/detail/GeantGeoNavCollection.hh:20:7: note: forward declaration of 'class G4VTouchable'
   20 | class G4VTouchable;

[sethrj]

Thanks @smuzaffar . This error looks like a simple IWYU but we'll make sure everything builds as expected first... and we'll try to be more on top of the Geant4 releases in the future now that we have downstream dependents!

[whokion]

Following up with MR, #1075