Initialization error when forwarding the initializers required by protocol ExpressibleByArrayLiteral or ExpressibleByDictionaryLiteral

Using Swift
, ,
3

This is the well-known variadic forwarding issue. A minimal example of your situation is:

struct Foo<T> {
  var base: T
}

extension Foo: ExpressibleByArrayLiteral where T: ExpressibleByArrayLiteral {
  init(arrayLiteral elements: T.ArrayLiteralElement...) {
    // Cannot invoke 'init' with an argument list of type '(arrayLiteral: [T.ArrayLiteralElement])'
    base = T.init(arrayLiteral: elements)
  }
}

Here are some previous threads about the topic:

• [Idea] Passing an Array to Variadic Functions (55 comments, April 2016)
• [Discussion] Variadics as an Attribute (7 comments, February 2017)
• Explicit array splat for variadic functions (29 comments, March 2018)
• Variadic Parameters that Accept Array Inputs (52 comments, May 2018)
• Another attempt at passing arrays as varargs (with implementation) (126 comments, July 2019)
• Yet another varargs “splat” proposal (9 comments, September 2019)

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