At the time of filing this issue, the package path passed to swift test is preceded with -C which I believe has been removed and replaced with --package-path since Swift 5.8.
https://github.com/apple/swift-source-compat-suite/blob/d8ff76a97fcfd178b54d473cbf5c053b70379c56/project.py#L370
Does this mean that Apple team is not actually running these test actions (at least for a while)? If I made some modification in the compiler, is it safe to test the changes against the listed test actions?