Merge branch '2.10.x'

Conflicts:
	src/compiler/scala/tools/nsc/doc/Settings.scala
	src/compiler/scala/tools/nsc/interpreter/CompletionOutput.scala
	src/compiler/scala/tools/nsc/matching/Patterns.scala
	src/compiler/scala/tools/nsc/transform/UnCurry.scala
	src/compiler/scala/tools/nsc/typechecker/Infer.scala
	src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
	src/compiler/scala/tools/nsc/typechecker/Typers.scala
	src/reflect/scala/reflect/internal/settings/MutableSettings.scala
	src/reflect/scala/reflect/runtime/Settings.scala
	src/swing/scala/swing/SwingActor.scala
	src/swing/scala/swing/SwingWorker.scala
	test/files/run/t6955.scala

1 files changed, 86 insertions, 15 deletions

diff --git a/src/library/scala/collection/generic/IsTraversableLike.scala b/src/library/scala/collection/generic/IsTraversableLike.scala
index b45279229b..c70772d8f9 100644
--- a/src/library/scala/collection/generic/IsTraversableLike.scala
+++ b/src/library/scala/collection/generic/IsTraversableLike.scala
@@ -9,26 +9,97 @@
 package scala.collection
 package generic
 
-/** Type class witnessing that a collection representation type `Repr` has
- *  elements of type `A` and has a conversion to `GenTraversableLike[A, Repr]`.
+/** A trait which can be used to avoid code duplication when defining extension
+ *  methods that should be applicable both to existing Scala collections (i.e.,
+ *  types extending `GenTraversableLike`) as well as other (potentially user-defined)
+ *  types that could be converted to a Scala collection type. This trait
+ *  makes it possible to treat Scala collections and types that can be implicitly
+ *  converted to a collection type uniformly. For example, one can provide
+ *  extension methods that work both on collection types and on `String`s (`String`s
+ *  do not extend `GenTraversableLike`, but can be converted to `GenTraversableLike`)
  *
- *  This type enables simple enrichment of `GenTraversable`s with extension
- *  methods which can make full use of the mechanics of the Scala collections
- *  framework in their implementation.
+ * `IsTraversable` provides two members:
+ *
+ *  1. type member `A`, which represents the element type of the target `GenTraversableLike[A, Repr]`
+ *  1. value member `conversion`, which provides a way to convert between the type we wish to add extension methods to, `Repr`, and `GenTraversableLike[A, Repr]`.
+ *
+ * ===Usage===
+ *
+ * One must provide `IsTraversableLike` as an implicit parameter type of an implicit
+ * conversion. Its usage is shown below. Our objective in the following example
+ * is to provide a generic extension method `mapReduce` to any type that extends
+ * or can be converted to `GenTraversableLike`. In our example, this includes
+ * `String`.
  *
- *  Example usage,
  * {{{
- *    class FilterMapImpl[A, Repr](val r: GenTraversableLike[A, Repr]) {
- *      final def filterMap[B, That](f: A => Option[B])(implicit cbf: CanBuildFrom[Repr, B, That]): That =
- *        r.flatMap(f(_).toSeq)
+ *    import scala.collection.GenTraversableLike
+ *    import scala.collection.generic.IsTraversableLike
+ *
+ *    class ExtensionMethods[A, Repr](coll: GenTraversableLike[A, Repr]) {
+ *      def mapReduce[B](mapper: A => B)(reducer: (B, B) => B): B = {
+ *        val iter = coll.toIterator
+ *        var res = mapper(iter.next())
+ *        while (iter.hasNext)
+ *          res = reducer(res, mapper(iter.next()))
+ *        res
+ *      }
  *    }
- *    implicit def filterMap[Repr, A](r: Repr)(implicit fr: IsTraversableOnce[Repr]): FilterMapImpl[fr.A,Repr] =
- *      new FilterMapImpl(fr.conversion(r))
  *
- *    val l = List(1, 2, 3, 4, 5)
- *    List(1, 2, 3, 4, 5) filterMap (i => if(i % 2 == 0) Some(i) else None)
- *    // == List(2, 4)
- * }}}
+ *    implicit def withExtensions[Repr](coll: Repr)(implicit traversable: IsTraversableLike[Repr]) =
+ *      new ExtensionMethods(traversable.conversion(coll))
+ *
+ *  // See it in action!
+ *  List(1, 2, 3).mapReduce(_ * 2)(_ + _) // res0: Int = 12
+ *  "Yeah, well, you know, that's just, like, your opinion, man.".mapReduce(x => 1)(_ + _) // res1: Int = 59
+ *}}}
+ *
+ * Here, we begin by creating a class `ExtensionMethods` which contains our
+ * `mapReduce` extension method. Note that `ExtensionMethods` takes a constructor
+ * argument `coll` of type `GenTraversableLike[A, Repr]`, where `A` represents the
+ * element type and `Repr` represents (typically) the collection type. The
+ * implementation of `mapReduce` itself is straightforward.
+ *
+ * The interesting bit is the implicit conversion `withExtensions`, which
+ * returns an instance of `ExtensionMethods`. This implicit conversion can
+ * only be applied if there is an implicit value `traversable` of type
+ * `IsTraversableLike[Repr]` in scope. Since `IsTraversableLike` provides
+ * value member `conversion`, which gives us a way to convert between whatever
+ * type we wish to add an extension method to (in this case, `Repr`) and
+ * `GenTraversableLike[A, Repr]`, we can now convert `coll` from type `Repr`
+ * to `GenTraversableLike[A, Repr]`. This allows us to create an instance of
+ * the `ExtensionMethods` class, which we pass our new
+ * `GenTraversableLike[A, Repr]` to.
+ *
+ * When the `mapReduce` method is called on some type of which it is not
+ * a member, implicit search is triggered. Because implicit conversion
+ * `withExtensions` is generic, it will be applied as long as an implicit
+ * value of type `IsTraversableLike[Repr]` can be found. Given that
+ * `IsTraversableLike` contains implicit members that return values of type
+ * `IsTraversableLike`, this requirement is typically satisfied, and the chain
+ * of interactions described in the previous paragraph is set into action.
+ * (See the `IsTraversableLike` companion object, which contains a precise
+ * specification of the available implicits.)
+ *
+ * ''Note'': Currently, it's not possible to combine the implicit conversion and
+ * the class with the extension methods into an implicit class due to
+ * limitations of type inference.
+ *
+ * ===Implementing `IsTraversableLike` for New Types===
+ *
+ * One must simply provide an implicit value of type `IsTraversableLike`
+ * specific to the new type, or an implicit conversion which returns an
+ * instance of `IsTraversableLike` specific to the new type.
+ *
+ * Below is an example of an implementation of the `IsTraversableLike` trait
+ * where the `Repr` type is `String`.
+ *
+ *{{{
+ * implicit val stringRepr: IsTraversableLike[String] { type A = Char } =
+ *   new IsTraversableLike[String] {
+ *     type A = Char
+ *     val conversion = implicitly[String => GenTraversableLike[Char, String]]
+ *   }
+ *}}}
  *
  * @author Miles Sabin
  * @author J. Suereth