libswift_Concurrency.dylib not found on macOS 10.15 & macOS 11

[miketimofeev]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

Describe the bug

Invoking swiftlint version on 0.49.0 produces an error:
dyld: Library not loaded: /usr/lib/swift/libswift_Concurrency.dylib Referenced from: /usr/local/bin/swiftlint Reason: image not found on macOS 10.15 and macOS 11. macOS 12 works fine though.

Complete output when running SwiftLint, including the stack trace and command used

n\a

Environment

We install swiftling using portable package via the installation script https://github.com/actions/runner-images/blob/main/images/macos/provision/core/swiftlint.sh

• Are you using nested configurations?
  If so, paste their relative paths and respective contents.
• Which Xcode version are you using (check xcodebuild -version)?
• Do you have a sample that shows the issue? Run echo "[string here]" | swiftlint lint --no-cache --use-stdin --enable-all-rules
  to quickly test if your example is really demonstrating the issue. If your example is more
  complex, you can use swiftlint lint --path [file here] --no-cache --enable-all-rules.

// This triggers a violation:
let foo = try! bar()

[miketimofeev]

@jpsim ugh, just noticed that breaking change

Does it mean we should stick to 0.48.0 for macOS 10.15 & macOS 11?

[jpsim]

That’s right, this was an intended breaking change in order to allow us to use swift concurrency features.

[jpsim]

We occasionally have “release candidate” releases like we did here for 0.49.0 (rc1 & rc2) to help users identify if there’s a breaking change or regression they need to flag with us or account for. Is there something I could do to make it easier for you to try the release candidates before official releases?

[miketimofeev]

Thanks for the suggestion but we try to avoid installing RC versions of tools to our images.

[jpsim]

I’m not saying you deploy RC changes, I’m saying we make RCs so people can proactively catch issues before they ship. How can I help you to do that?

[miketimofeev]

I'm afraid our tests during the VM image generation cover only basic scenarios like version output so in most cases we won't be able to test the RC versions properly without providing the image with such new versions to customers.