Issue overview

Upgrading fmt from the current version of 8.0.1 to 10+ will require significant work to get the custom double formats to match the old fortran formats (Z, S, N, R).

I'm speaking about what is done around here: https://github.com/NREL/EnergyPlus/blob/1033bdc61ccda944a6844344f9ba18e76ffa53d1/src/EnergyPlus/IOFiles.hh#L95

It's not impossible to do it, but since (I believe) these were provided so the I/O upgrade to fmt could pass without CI diffs (so we could trust the upgrade), maybe it's time to just remove these formats, and accept the diffs?

Notes:

1. Why upgrade fmt?
   • Not saying this needs to be done now, but just anticipating that at some point we will want to do it.
   • it seems like this is going to be required to bring the codebase to C++20 and above (from my limited testing enabling C++20 instead of C++17).
   • And recent fmt versions gained interesting functionality like formatting std::filesystem::path out of the box, etc.
2. The reason there is work to be done is that fmt internals changed, and the specs_.type is no longer a char but an actual enum, so rewritting it requires more effort.

Details

Some additional details for this issue (if relevant):

• Platform (Operating system, version): all
• Version of EnergyPlus (if using an intermediate build, include SHA): 1033bdc

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

• Defect file added (list location of defect file here)
• Ticket added to EnergyPlus Defect Complexity (Github Project)
• Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)