swift234

If an assumption that binds a type variable to a class type fails, try
binding to its superclass instead. This, plus a tiny hack to deal with
our utter lack of meet/join computation, lets us define a ternary
operator-like function as

func ternary<T>(cond : Bool, 
                ifTrue : [auto_closure] () -> T, 
                ifFalse : [auto_closure] () -> T) -> T {}

and call it with values of different class types, e.g.,

  ternary(something, b, c)

and the type checker will deduce the common base class of b and c.



Swift SVN r2747