I have trailing_closure where is not

[hrvoje0099]

New Issue Checklist

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

Describe the bug

The code has no closure as an argument, so the trailing closure syntax cannot be applied.

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

Linting Swift files in current working directory
Linting 'validate_words.swift' (1/1)
/Users/vukovihr/Desktop/test_skript/validate_words.swift:14:12: warning: Operator Function Whitespace Violation: Operators should be surrounded by a single whitespace when defining them (operator_whitespace)
/Users/vukovihr/Desktop/test_skript/validate_words.swift:8:1: warning: Trailing Whitespace Violation: Lines should not have trailing whitespace (trailing_whitespace)
/Users/vukovihr/Desktop/test_skript/validate_words.swift:48:1: warning: Trailing Whitespace Violation: Lines should not have trailing whitespace (trailing_whitespace)
/Users/vukovihr/Desktop/test_skript/validate_words.swift:51:1: warning: Trailing Whitespace Violation: Lines should not have trailing whitespace (trailing_whitespace)
/Users/vukovihr/Desktop/test_skript/validate_words.swift:54:1: warning: Trailing Whitespace Violation: Lines should not have trailing whitespace (trailing_whitespace)
Done linting! Found 5 violations, 0 serious in 1 file.

Environment

• SwiftLint version (run swiftlint version to be sure)? 👉 0.52.4
• Installation method used (Homebrew, CocoaPods, building from source, etc)? 👉 Homebrew
• Which Xcode version are you using (check xcodebuild -version)? 👇

Xcode 14.3.1
Build version 14E300c

[SimplyDanny]

The rule complains about the closure argument of the handleEvents method but triggers always at the very beginning of the chain.

The rule, therefore, is correct but the trigger location should be improved to be the method with the closure argument itself.

[hrvoje0099]

But receiveOutput is not the last argument in the handleEvents method, what can I do there? What can I do to make the warning disappear? Thank you

[SimplyDanny]

How is handleEvents defined?

[hrvoje0099]

func handleEvents(receiveSubscription: ((Subscription) -> Void)? = nil, receiveOutput: ((Self.Output) -> Void)? = nil, receiveCompletion: ((Subscribers.Completion<Self.Failure>) -> Void)? = nil, receiveCancel: (() -> Void)? = nil, receiveRequest: ((Subscribers.Demand) -> Void)? = nil) -> Publishers.HandleEvents<Self>

https://developer.apple.com/documentation/combine/anypublisher/handleevents(receivesubscription:receiveoutput:receivecompletion:receivecancel:receiverequest:)

[SimplyDanny]

In this case, it's really a bug in the rule. Using a trailing closure would not compile or lead to semantical changes which is not okay. However, since this rule operators on syntax-level without type information and, in your case, function signature information only, it cannot do better. We have to live with such false positives if the rule shall at the same time be very fast, unfortunately.

SwiftLint also offers so called "Analyzer Rules" which have a deeper knowledge about types and exact signatures. They are very slow and a separate SwiftLint run is required, on the other hand.