Ruff fix functions return successful Changesets after Ruff exits with a usage error #99

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1. aoright commented on Sep 24, 2026

   

   aoright

   on Sep 24, 2026

   More actions

   I implemented and verified a targeted fix for this issue on fork branch fix/ruff-fix-exit-code (commit ac3baf0).

   Compare: main...aoright:daggerverse:fix/ruff-fix-exit-code

   1. Root Cause & Ruff Exit Code Semantics

   • expect=dagger.ReturnType.ANY was introduced so that ruff check --fix does not fail Dagger's execution when unfixable lint violations remain (which Ruff signals via exit code 1 while still applying auto-fixes to disk).
   • However, Ruff adheres to standard CLI conventions:
     • Exit 0: Success (clean / all fixes applied).
     • Exit 1: Lint violations remain (only possible in check).
     • Exit 2+: Command-line usage errors (e.g. invalid/unsupported extra_args), invalid configuration, syntax parsing crashes, or internal runtime failure.
   • Similarly, ruff format (without --check) succeeds on exit 0; any non-zero exit code represents a failure.
   • By omitting an explicit exit code check after result = ctr.with_exec(..., expect=dagger.ReturnType.ANY), exit code 2 errors were suppressed and resulted in false-success Changeset objects.

   2. Implementation

   In ruff/src/ruff/checker.py:

           ctr = self._container(source)
           result = ctr.with_exec(args, expect=dagger.ReturnType.ANY)
           output = await result.combined_output()
           if output.strip():
               sys.stderr.write(output)
           exit_code = await result.exit_code()
           if exit_code > 1:
               msg = f"Ruff check failed with exit code {exit_code}:\n{output}"
               raise RuntimeError(msg)
           before = dag.directory().with_directory(".", source)
           fixed = result.directory("/work").without_directory(".ruff_cache")
           after = dag.directory().with_directory(".", fixed)
           return after.changes(before)

   In ruff/src/ruff/formatter.py:

           ctr = self._container(source)
           result = ctr.with_exec(args, expect=dagger.ReturnType.ANY)
           output = await result.combined_output()
           if output.strip():
               sys.stderr.write(output)
           exit_code = await result.exit_code()
           if exit_code != 0:
               msg = f"Ruff format failed with exit code {exit_code}:\n{output}"
               raise RuntimeError(msg)
           before = dag.directory().with_directory(".", source)
           fixed = result.directory("/work").without_directory(".ruff_cache")
           after = dag.directory().with_directory(".", fixed)
           return after.changes(before)

   Verified with ruff check and ruff format (0 findings).
2. aoright commented on Sep 24, 2026

   

   aoright

   on Sep 24, 2026

   More actions

   Opened PR #106 with the zero-regression fix and test coverage.
3. danielgafni

   closed this as completedin #114on Oct 11, 2026