buf breaking

needs a previous state to compare against in order to detect breaking changes. My naive approach is to simply piggyback on Pants'

pants.base.build_environment.get_git

and

pants.vcs.changed.ChangedOptions

functionality.

get_git

to get the git workdir (from the currently protected

_gitdir

attribute) and `ChangedOptions.diffspec`/`ChangedOptions.since` to get the rev to compare the local tree against. If `ChangedOptions.diffspec`/`ChangedOptions.since` it can fall back on

HEAD

, and if

get_git

returns

None

then the linter will be skipped I guess? I'm not entirely sure how to put it all together.

get_git

seems to be callable from anywhere, so that should be simple enough, but

ChangedOptions

I'm struggling to get into my linter rule, probably because it's not intended to be used directly by rules but rather to determine which sources to provide the rules with. I'm also pondering about on how to structure the code and its options. The current linter is located in

pants/backend/codegen/protobuf/lint/buf

. Is this even a linter, or is a test or a check? Right now I've renamed the current

rules.py

to

lint_rules.py

and have introduce

breaking_rules.py

. I imagine people will want the option to only enable/disable one of them, so bundling them in the same backend might not be the best approach. Then there's also the subsystem which I, of course, want to reuse for both, but should it be extended so

lint

and

breaking

have different

options_scope

perhaps? I appreciate any and all feedback 🖖