Issue with PODIO in eic-shell on MAC

[Meatbally2]

Hi all,

There seems to be an issue when using PODIO in eic-shell to access EICrecon simulation campaign files on macOS. Below is a small test code:

R__LOAD_LIBRARY(libpodio.so)
R__LOAD_LIBRARY(libpodioRootIO.so)
R__LOAD_LIBRARY(libedm4hep.so)
R__LOAD_LIBRARY(libedm4hepDict.so)
R__LOAD_LIBRARY(libedm4hepUtils.so)
R__LOAD_LIBRARY(libedm4hepRDF.so)
R__LOAD_LIBRARY(libedm4eic.so)
R__LOAD_LIBRARY(libedm4eicDict.so)

#include "podio/Frame.h"
#include "podio/ROOTReader.h"
#include "edm4hep/MCParticleCollection.h"

void podio_test()
{
    
    podio::ROOTReader* reader = new podio::ROOTReader();
    reader->openFile("root://dtn-eic.jlab.org:1094//volatile/eic/EPIC//RECO/26.02.0/epic_craterlake/DIS/NC/18x275/minQ2=10/pythia8NCDIS_18x275_minQ2=10_beamEffects_xAngle=-0.025_hiDiv_1.0000.eicrecon.edm4eic.root");

    for( size_t ev = 0; ev < reader->getEntries("events"); ev++ )
    {   
        auto raw = reader->readEntry("events", ev);  // Use readEntry with index instead
        podio::Frame event(std::move(raw));

        edm4hep::MCParticleCollection meMC;
	    meMC.setSubsetCollection();

        for (const auto& mcp : event.get<edm4hep::MCParticleCollection>("MCParticles")) 
        {
        if ( mcp.getPDG() == 11 && mcp.getGeneratorStatus() == 1 ) 
            meMC.push_back(mcp);
        }
    }

    return;
}

When running this code with eic-shell on MAC, the following error is returned:

root [0] 
Processing podio_test.C...
In file included from input_line_8:1:
/Users/winl/eic/eicDIS/podio_test.C:27:20: error: call to deleted constructor of 'edm4hep::MCParticleCollection const'
        const auto mcparts = event.get<edm4hep::MCParticleCollection>("MCParticles");
                   ^         ~~~~~~~~~~~
libedm4hepDict dictionary payload:2377:3: note: 'MCParticleCollection' has been explicitly marked deleted here
  MCParticleCollection(const MCParticleCollection&) = delete;
  ^
In file included from input_line_8:1:
In file included from /Users/winl/eic/eicDIS/podio_test.C:10:
/opt/local/include/podio/Frame.h:398:12: error: reference to type 'const edm4hep::MCParticleCollection' could not bind to an lvalue of type 'const auto'
    return *coll;
           ^~~~~
/Users/winl/eic/eicDIS/podio_test.C:27:36: note: in instantiation of function template specialization 'podio::Frame::get<edm4hep::MCParticleCollection>' requested here
        const auto mcparts = event.get<edm4hep::MCParticleCollection>("MCParticles");
                                   ^

 * Break * segmentation violation

The issue does not occur when running the same code on non-MAC machines.

Environment: (where does this bug occur, have you tried other environments)

• Which branch (often main for latest released): latest
• Which version (or HEAD for the most recent on git): latest
• Any specific OS or system where the issue occurs? MAC OS
• Any special versions of ROOT or Geant4?

Steps to reproduce: (give a step by step account of how to trigger the bug)

1. Run latest eic-shell ( or version after 25.12) on MAC
2. Run the testing code above

Expected Result: (what do you expect when you execute the steps above)

Root macro runs without error.

Actual Result: (what do you get when you execute the steps above)

Root returns error as shown above.

[Meatbally2]

There is a workaround for MAC, but it is not clear why the above code does not work.

R__LOAD_LIBRARY(libpodio.so)
R__LOAD_LIBRARY(libpodioRootIO.so)
R__LOAD_LIBRARY(libedm4hep.so)
R__LOAD_LIBRARY(libedm4hepDict.so)
R__LOAD_LIBRARY(libedm4hepUtils.so)
R__LOAD_LIBRARY(libedm4hepRDF.so)
R__LOAD_LIBRARY(libedm4eic.so)
R__LOAD_LIBRARY(libedm4eicDict.so)

#include "podio/Frame.h"
#include "podio/ROOTReader.h"
#include "edm4hep/MCParticleCollection.h"


void podio_test_v1()
{
    podio::ROOTReader reader; 
    reader.openFile("root://dtn-eic.jlab.org:1094//volatile/eic/EPIC//RECO/26.02.0/epic_craterlake/DIS/NC/18x275/minQ2=10/pythia8NCDIS_18x275_minQ2=10_beamEffects_xAngle=-0.025_hiDiv_1.0000.eicrecon.edm4eic.root");

    for(size_t ev = 0; ev < reader.getEntries("events"); ev++)
    {   
        auto raw = reader.readEntry("events", ev);
        podio::Frame event(std::move(raw));

        edm4hep::MCParticleCollection meMC;
        meMC.setSubsetCollection();

        auto* collBase = event.get("MCParticles");
        
        if (collBase) {
            const auto& mcparts = static_cast<const edm4hep::MCParticleCollection&>(*collBase);

            for (const auto& mcp : mcparts) 
            {
                if (mcp.getPDG() == 11 && mcp.getGeneratorStatus() == 1) 
                    meMC.push_back(mcp);
            }
        }
    }
}