swift234

Implement another new closure syntax.

In this syntax, the closure signature (when present) is placed within
the braces and the 'in' keyword separates it from the body of the
closure, e.g.,

      magic(42, { (x : Int, y : Int) -> Bool in
        print("Comparing \(x) to \(y).\n")
        return y < x
      })

When types are omitted from the parameter list, one can also drop the
parentheses, e.g.,

      magic(42, { x, y -> Bool in
        print("Comparing \(x) to \(y).\n")
        return y < x
      })

The parsing is inefficient and recovers poorly (in part because 'in'
is a contextual keyword rather than a real keyword), but it should
handle the full grammar. A number of tests, along with the whitepaper
and related rational documents, still need to be updated. Still, this
is the core of <rdar://problem/14004323>.



Swift SVN r6105