Implementing ExpressibleByTupleLiteral: how hard?

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For @tupleLiteral, you mentioned that the init signature would be the tuple literal, but it might be a little inconsistent with the other attributes for those being the argument for the designated initializer. i.e. :

// integer literal
struct Integer {
  // Notice that the literal value is the argument
  @integerLiteral
  init(integerLiteral value: Int) {}
}

let int: Integer = 0

// tuple literal

struct X {
  // Literal value here is the initializer itself
  @tupleLiteral
  init(y: Int, z: Bool) {}
} 

let x: X = (y: 0, z: true)

// vs.

struct X {
  // Tuple literal is the argument
  @tupleLiteral
  init(tupleLiteral value: (y: Int, z: Bool)) {}
}

let x: X = (y: 0, z: true)

Also, @tupleLiteral initializers would be kind of awkward with types that have a single argument (single argument tuples with labels are banned):

// Silly example, but maybe there are use cases
// for a single argument tuples
struct BoolWrapper {
  @tupleLiteral
  init(bool: Bool) {}
}

// error: cannot create a single-element tuple
//        with an element label
let boolThing: BoolWrapper = (bool: true)

These are just some design thoughts I had after the discussion because I might be interested in toying around with this when I get the chance.