Rule request: avoid calling init(arrayLiteral:)

[marcelofabri]

ExpressibleByArrayLiteral protocol declares init(arrayLiteral elements: Element...), but according to the documentation it shouldn't be called directly.

The types that implement this protocol are:

• Array
• ArraySlice
• ContiguousArray
• IndexPath
• NSArray
• NSCountedSet
• NSMutableArray
• NSMutableOrderedSet
• NSMutableSet
• NSOrderedSet
• NSSet
• SBElementArray
• Set

List obtained from https://developer.apple.com/reference/swift/expressiblebyarrayliteral

[keith]

@marcelofabri quick question on this one, I see the info in the init(arrayLiteral docs, but not in the ExpressibleByIntegerLiteral protocol. Is there info somewhere about not calling this?

[marcelofabri]

@keith Not directly, but I think we can generalize it for all protocols in this "family" based on the proposal that renamed them:

No, it's exactly the opposite, as I keep saying.  Conformance to this
protocol does *not* mean you can initialize the type with a literal.

  func f<T: IntegerLiteralConvertible>() -> T {
    return T(integerLiteral: 43) // Error
    return T(43)                 // Also an Error
  }

// It means an instance of the type can be *written* as a literal:

  func f<T: IntegerLiteralConvertible>() -> T {
    return 43   // OK
  }

[ghost]

Another example:

    _ = Calendar.current.dateComponents(Set(arrayLiteral: Calendar.Component.hour, Calendar.Component.minute, Calendar.Component.second, Calendar.Component.nanosecond), from: Date())

The above works but is not necessary to call Set(arrayLiteral: ...).

_ = Calendar.current.dateComponents([Calendar.Component.year, Calendar.Component.month, Calendar.Component.day], from: Date())