Multiline arguments violation with multiple trailing closures

[jakubkiermasz-zd]

New Issue Checklist

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

Describe the bug

For below code

talkProvider.getAvailability(forUser: userId) { [weak self] response in
    self?.handleSuccess(response)
} onError: { [weak self] _ in
    self?.handleError()
}

I receive this warning: Multiline Arguments Violation: Arguments should be either on the same line, or one per line. (multiline_arguments)

Environment

• SwiftLint version (run swiftlint version to be sure)? 0.43.1
• Installation method used (Homebrew, CocoaPods, building from source, etc)? Pods
• Are you using nested configurations? nope
• Which Xcode version are you using (check xcodebuild -version)? Xcode 12.4 Build version 12D4e
• Do you have a sample that shows the issue? Yes, it is. Done linting! Found 1 violation, 0 serious in 1 file.

[Sonal-Kachare]

To resolve this warning I did following changes to function declaration

Existing function declaration:

func getAvailability(forUser: Int, _ onSuccess: @escaping (String) -> Void, onError: (String) -> Void) { }

Updated function declaration

func getAvailability(forUser: Int, onSuccess: @escaping (String) -> Void, onError: (String) -> Void) { }

Usage of updated function:

getAvailability(forUser: 10, onSuccess: { (_) in

}, onError: { (_) in

})

[jakubkiermasz-zd]

@Sonal-Kachare Thank you for your answer! Of course, the code you've proposed is correct, but unfortunately, it doesn't use the trailing closure feature, which is powerful and recommended in Swift 5.3+.

[holgerde]

When you use a SwiftUI TextField, Xcode will generate this code for you:

TextField("Title", text: $text) { isEditing in
    // ...
} onCommit: {
    // ...
}

So this is definitely the recommended syntax and should not trigger a multiline arguments violation.

[jakubkiermasz-zd]

@marcelofabri could you take a look at this, please :)?

[dnadoba]

I run into a similar issue with multiple trailing closures but for the vertical_parameter_alignment_on_call rule:

PreviewView(
    previewLayout: .fitWidth(360)
) {
    SomeView()
} update: {
    $0.update(data: data)
}

Which creates the following warning:

Vertical Parameter Alignment On Call Violation: Function parameters should be aligned vertically if they're in multiple lines in a method call. (vertical_parameter_alignment_on_call)

[gentges]

Any news on the status of this issue? I'm still getting this warning in version 0.47.1.

[edelabar]

Also seeing this in 0.47.1.

Custom signature:

init(
	_ title: String,
	@ViewBuilder leftButtonBuilder: () -> LeftButton,
	@ViewBuilder rightButtonBuilder: () -> RightButton
)

Failing Invocation (multiline_arguments):

TitleBar("Profile") {
	backButton
} rightButtonBuilder: {
	editButton
}

Also tried...

Fails multiline_arguments_brackets and vertical_parameter_alignment_on_call:

TitleBar("Profile")
{
	backButton
} rightButtonBuilder: {
	editButton
}

Works, but not ideal:

TitleBar(
	"Profile",
	leftButtonBuilder: {
		backButton
	}, rightButtonBuilder: {
		editButton
	}
)

[yo1995]

It seems like a workaround would be config it differently:

multiline_arguments:
  only_enforce_after_first_closure_on_first_line: true

Please refer to https://realm.github.io/SwiftLint/multiline_arguments.html

[marcelofabri]

This should've been fixed by https://github.com/realm/SwiftLint/pull/4750