False positive in unused_closure_parameter

[jpsim]

New Issue Checklist

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

Bug Report

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

$ swiftlint lint --path test.swift
Linting Swift files at path test.swift
Linting 'test.swift' (1/1)
/Users/jsimard/Downloads/test.swift:3:5: warning: Unused Closure Parameter Violation: Unused parameter "manager" in a closure should be replaced with _. (unused_closure_parameter)
Done linting! Found 1 violation, 0 serious in 1 file.

Environment

• SwiftLint version (run swiftlint version to be sure)?

0.24.0

• Installation method used (Homebrew, CocoaPods, building from source, etc)?

Homebrew

• Paste your configuration file:

None.

• Are you using nested configurations?
  If so, paste their relative paths and respective contents.

None.

• Which Xcode version are you using (check xcode-select -p)?

/Applications/Xcode-9.2.app/Contents/Developer

• 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.

import Foundation

({ (manager: FileManager) in
  print(manager)
})(FileManager.default)

Also, as reported by @irace:

[irace]

What customer service – thanks JP!

…

On Dec 21, 2017, 3:17 PM -0500, JP Simard ***@***.***>, wrote: New Issue Checklist • Updated SwiftLint to the latest version • I searched for existing GitHub issues Bug Report Complete output when running SwiftLint, including the stack trace and command used $ swiftlint lint --path test.swift Linting Swift files at path test.swift Linting 'test.swift' (1/1) /Users/jsimard/Downloads/test.swift:3:5: warning: Unused Closure Parameter Violation: Unused parameter "manager" in a closure should be replaced with _. (unused_closure_parameter) Done linting! Found 1 violation, 0 serious in 1 file. Environment • SwiftLint version (run swiftlint version to be sure)? 0.24.0 • Installation method used (Homebrew, CocoaPods, building from source, etc)? Homebrew • Paste your configuration file: None. • Are you using nested configurations? If so, paste their relative paths and respective contents. None. • Which Xcode version are you using (check xcode-select -p)? /Applications/Xcode-9.2.app/Contents/Developer • 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. import Foundation ({ (manager: FileManager) in print(manager) })(FileManager.default) Also, as reported by @irace: — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or mute the thread.

[jpsim]

So SourceKit is returning some BS with closures of this format. Here's what it thinks the name of the closure is: ({ (manager: FileManager) in\n print(manager)\n}), and the body is (FileManager.default).

Looking into making a workaround.

[marcelofabri]

This would be way easier/more reliable if we SourceKit returned closures in the structure (https://bugs.swift.org/browse/SR-6116). I started implementing it a few months ago, but it looks like I lost my WIP branch ¯_(ツ)_/¯