My take is that they should always be committed, but never generated by the dev, instead generated and pushed when necessary by CI. The problem with generating those files yourself is that, in many cases, it makes the output nondeterministic and nonreproducible. In the ideal world those tools would just generate those files deterministically, but until then for me committing them from CI is an acceptable stopgap
My preference is to do both. Have them generated by a dev, committed, and also generated in CI. The latter gets compared with the checked in contents to ensure the results match the expected value.
This speeds up CI (the generation path can be done in parallel) and most local development.
The one catch is that it relies on mostly trusting whoever has a commit bit. But if you don’t have that and any part of the build involves scripts that are part of the repo itself, then you’ve already lost.
My preference is to do both. Have them generated by a dev, committed, and also generated in CI. The latter gets compared with the checked in contents to ensure the results match the expected value.
Bingo. This is what I am working towards convincing people to adopt at my current job. It's a long road.
The generation routine bits would be highly specific to the project, but the final check in CI is as simple checking the git diff/status of the generated targets to see if they match the ref. Any deviance indicates that it’s been missed by the patch submitter (likely inadvertently in the case of honest actors).
The real work is being able to transform the generation task into a reproducible step that be run consistently anywhere. Containerizing those steps can help but it’s not strictly required nor is it enough if the “inputs” are a non-seeded random or the current time.
That's not the case for autotools output, or flex and bison output.
If the generated files are what you say? Well, just embed the generation step into the build system. A simple approach like that is easily made reproducible, and we avoid introducing noise into the repository.
