swift234

Teach the constraint solver to make guesses about type variable
bindings based on lower/upper bounds for that type variable. This is
woefully inadequate, but it's enough to allow us to resolve

  func f(_ : Float) -> Float {}
  func f(_ : Int) -> Int {}

  f(1.0)

to the first overload. Note that

  f(1)

remains ambiguous (because both Int and Float can be built from
integer literals).

Annoyingly,

  func f(x : Float) -> Float {}
  func f(y : Int) -> Int {}

  f(1.0)

is ill-formed because we choose (x : Float) for the type of the
integer literal expression, which then fails the integer-literal
check. Solution TBD.



Swift SVN r2704