Generating .cpp.inc files for dialects?

I noticed that we don’t generate .cpp.inc files for dialects (only .h.inc). Was there a reason for this, or just never got done?

I’ve witnessed a handful of design decisions over the months punt to easy ways out when the best option really would have been (imo) having dropped a few lines of generated code in the DialectGen backend. Unless if there was a reason for this omission, I propose that we close this gap and start generating these files.

In order to help out-of-tree users adapt, I would like to enable generation of these files for the core project but keep them empty for a period of transition time. Then when we have the next use for them, they would become required. Any objections?

When I added dialect gen there was nothing to generate in the .cpp, so I didn’t add support for that. If there is something that could/should be placed in the .cpp, I’m fine with adding a generator for it.

– River

Initial draft: https://reviews.llvm.org/D105070

I have not updated all dialects yet. Sending out for comment prior to finishing out with that mechanical work.