Pythia8 not built agains HepMC3

[dirkzerwas]

Hi @jmcarcell, after discussion with the MCGenerator authors, adding pythia8 to the k4GeneratorsConfiguration worked only partially:

• compiles and runs
• but the hepmc3 plugin does not seem to be availlable to write hepmc3 output . Adding the Sjostrand recipe of main144, the primary include file "Pythia8Plugins/HepMC3.h" exists, but then the proper "HepMC3::GenEvent.h" etc cannot be found. It looks kind of like pythia8 was compiled/installed without the HepMC3 package Cheers, Dirk

[tmadlener]

The fact that pythia8 is not compiled with hepmc3 support can also be verified with

$ pythia8-config --with-hepmc3
false

Just to add a bit more spack information here, we also just tried to do the following (locally in my stack):

pythia8:
  require: "+gzip +hempc3"

and we ran into a (non-descriptive) concretization error. It was not immediately clear to me where this conflict comes from. At least simply grepping for "pythia8" in spack and key4hep-spack doesn't yield any obvious conflict. However, something must require pythia8~hepmc3, because by default the hepmc3 variant is on in pythia8.

[jmcarcell]

Let's see tomorrow with #611, see the explanation there.

[jmcarcell]

It seems to be fine now

[dirkzerwas]

Checked: compiled and ran without a hitch, thanks!