sams could play nicer with overloading

[scabug]

import java.util._

object TestOkay {
  def sort(x: java.util.Comparator[_ >: String]) = ()
  sort((a: String, b: String) => a.compareToIgnoreCase(b))
}

object TestOkay2 {
  def sort[T](x: java.util.Comparator[_ >: T]) = ()
  sort((a: String, b: String) => a.compareToIgnoreCase(b))
}


object TestOkay3 {
  def sort[T](xs: Option[T], x: java.util.Comparator[_ >: T]) = ()
  sort(Some(""), (a: String, b: String) => a.compareToIgnoreCase(b))
}

object TestKoOverloaded {
  def sort[T](xs: Option[T]) = ()
  def sort[T](xs: Option[T], x: java.util.Comparator[_ >: T]) = ()
  sort(Some(""), (a: String, b: String) => a.compareToIgnoreCase(b))
}

Overloading resolution type checks the function literal without an expected type, and then discards the overloaded alternative as Function1 doesn't conform to Comparator.

Java can handle this, presumably because it filters overloaded alternatives based on arity first (we filter them based on isApplicable, which might tuple args, add defaults, etc).

Maybe this will wind up as a wont-fix, but we should document the limitation in the SAM SIP for 2.12.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-8310?orig=1
Reporter: @retronym
Affected Versions: 2.11.0-M8

[scabug]

@adriaanm said:
scala/scala#4101