swift234

Teach the constraint checker that it's okay to pick a type involving type variables as a bound.

Among other things, this change allows us to type-check uses of array
literals passed to generic functions. From Joe's pre-existing test
for this feature:

  class List<T> /*: ArrayLiteralConvertible*/ {
    typealias Element = T
    static func convertFromArrayLiteral(xs:T...) -> List<T> {}
  }

  func useList<T>(l:List<T>) {}

  useList([1,2,3]) // T=Int
  useList([1.0,2,3]) // T=Double




Swift SVN r4131