Rule Request: prefer 'joined()' over 'joined(separator: "")'

[jpsim]

since that's the default separator.

[ghost]

Does SourceKitten provide sufficient detail to make this rule more general? In other words, detect any instance where a function is being used with its default arguments.

[marcelofabri]

I don't think so, we'd have to keep a list with known functions and default parameters.

[jpsim]

Does SourceKitten provide sufficient detail to make this rule more general?

No, it doesn't, because binary Swift modules don't actually contain that information 😱

For example, looking at the generated interface for the Swift standard library in Xcode itself, you get this:

extension Array where Element == String {
    public func joined(separator: String = default) -> String
}

Notice the default in the place where you'd expect to see "".

I actually think (I could be wrong) that this has something to do with Swift's planned ABI stability. But I'm not sure.

[marcelofabri]

Closed by @ornithocoder in #1746 🎉