9 files changed, 77 insertions, 19 deletions
diff --git a/bincompat-forward.whitelist.conf b/bincompat-forward.whitelist.conf
index 13e4f4ba85..3808083dd3 100644
--- a/bincompat-forward.whitelist.conf
+++ b/bincompat-forward.whitelist.conf
@@ -314,6 +314,11 @@ filter {
     {
         matchName="scala.reflect.runtime.Settings#IntSetting.valueSetByUser"
         problemName=MissingMethodProblem
+    },
+    // SI-9059
+    {
+        matchName="scala.util.Random.scala$util$Random$$nextAlphaNum$1"
+        problemName=MissingMethodProblem
     }
   ]
 }
diff --git a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
index 743bbe53bd..02356580cc 100644
--- a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
@@ -266,7 +266,6 @@ abstract class TreeCheckers extends Analyzer {
 
       if (tree ne typed)
         treesDiffer(tree, typed)
-
       tree
     }
 
diff --git a/src/library/scala/collection/SetLike.scala b/src/library/scala/collection/SetLike.scala
index 3e549f72cd..f8ac1d754d 100644
--- a/src/library/scala/collection/SetLike.scala
+++ b/src/library/scala/collection/SetLike.scala
@@ -107,22 +107,36 @@ self =>
    */
   def + (elem: A): This
 
-  /** Creates a new $coll with additional elements.
+  /** Creates a new $coll with additional elements, omitting duplicates.
    *
-   *  This method takes two or more elements to be added. Another overloaded
-   *  variant of this method handles the case where a single element is added.
+   *  This method takes two or more elements to be added. Elements that already exist in the $coll will
+   *  not be added. Another overloaded variant of this method handles the case where a single element is added.
+   *
+   *  Example:
+   *   {{{
+   *    scala> val a = Set(1, 3) + 2 + 3
+   *    a: scala.collection.immutable.Set[Int] = Set(1, 3, 2)
+   *   }}}
    *
    *  @param elem1 the first element to add.
    *  @param elem2 the second element to add.
    *  @param elems the remaining elements to add.
-   *  @return   a new $coll with the given elements added.
+   *  @return   a new $coll with the given elements added, omitting duplicates.
    */
   def + (elem1: A, elem2: A, elems: A*): This = this + elem1 + elem2 ++ elems
 
-  /** Creates a new $coll by adding all elements contained in another collection to this $coll.
+  /** Creates a new $coll by adding all elements contained in another collection to this $coll, omitting duplicates.
+   *
+   * This method takes a collection of elements and adds all elements, omitting duplicates, into $coll.
+   *
+   * Example:
+   *  {{{
+   *    scala> val a = Set(1, 2) ++ Set(2, "a")
+   *    a: scala.collection.immutable.Set[Any] = Set(1, 2, a)
+   *  }}}
    *
-   *  @param elems     the collection containing the added elements.
-   *  @return a new $coll with the given elements added.
+   *  @param elems     the collection containing the elements to add.
+   *  @return a new $coll with the given elements added, omitting duplicates.
    */
   def ++ (elems: GenTraversableOnce[A]): This = (repr /: elems.seq)(_ + _)
 
@@ -171,7 +185,7 @@ self =>
    *
    *  @return     the iterator.
    */
-  def subsets: Iterator[This] = new AbstractIterator[This] {
+  def subsets(): Iterator[This] = new AbstractIterator[This] {
     private val elms = self.toIndexedSeq
     private var len = 0
     private var itr: Iterator[This] = Iterator.empty
diff --git a/src/library/scala/util/Random.scala b/src/library/scala/util/Random.scala
index 8d68c5be38..2d38c9d4a0 100644
--- a/src/library/scala/util/Random.scala
+++ b/src/library/scala/util/Random.scala
@@ -121,15 +121,21 @@ class Random(val self: java.util.Random) extends AnyRef with Serializable {
     (bf(xs) ++= buf).result()
   }
 
+  @deprecated("Preserved for backwards binary compatibility. To remove in 2.12.x.", "2.11.6")
+  final def `scala$util$Random$$isAlphaNum$1`(c: Char) = (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9')
+
   /** Returns a Stream of pseudorandomly chosen alphanumeric characters,
    *  equally chosen from A-Z, a-z, and 0-9.
    *
    *  @since 2.8
    */
   def alphanumeric: Stream[Char] = {
-    def isAlphaNum(c: Char) = (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9')
+    def nextAlphaNum: Char = {
+      val chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
+      chars charAt (self nextInt chars.length)
+    }
 
-    Stream continually nextPrintableChar filter isAlphaNum
+    Stream continually nextAlphaNum
   }
 
 }
diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala
index ce36f7efa3..8f114caac0 100644
--- a/src/reflect/scala/reflect/internal/Types.scala
+++ b/src/reflect/scala/reflect/internal/Types.scala
@@ -1976,13 +1976,13 @@ trait Types
      * usage scenario.
      */
     private var relativeInfoCache: Type = _
-    private var memberInfoCache: Type = _
+    private var relativeInfoPeriod: Period = NoPeriod
 
-    private[Types] def relativeInfo = {
-      val memberInfo = pre.memberInfo(sym)
-      if (relativeInfoCache == null || (memberInfo ne memberInfoCache)) {
-        memberInfoCache = memberInfo
+    private[Types] def relativeInfo = /*trace(s"relativeInfo(${safeToString}})")*/{
+      if (relativeInfoPeriod != currentPeriod) {
+        val memberInfo = pre.memberInfo(sym)
         relativeInfoCache = transformInfo(memberInfo)
+        relativeInfoPeriod = currentPeriod
       }
       relativeInfoCache
     }
diff --git a/test/files/pos/t9116.scala b/test/files/pos/t9116.scala
new file mode 100644
index 0000000000..16b04c2e6b
--- /dev/null
+++ b/test/files/pos/t9116.scala
@@ -0,0 +1,7 @@
+
+trait X {
+  List(1, 2, 3).toSet.subsets.map(_.toList)     // ok now
+
+  List(1, 2, 3).toSet.subsets().map(_.toList)   // now also
+  List(1, 2, 3).toSet.subsets(2).map(_.toList)  // still ok
+}
diff --git a/test/files/pos/t9157.scala b/test/files/pos/t9157.scala
new file mode 100644
index 0000000000..e178b5d84d
--- /dev/null
+++ b/test/files/pos/t9157.scala
@@ -0,0 +1,13 @@
+trait Flow[-In, +Out] {
+  type Repr[+O] <: Flow[In, O]
+  def map: Repr[String]
+}
+
+class Test {
+  // typechecking was exponentially slow wrt the number of projections here.
+  def slowFlow(
+    f: Flow[String,String]#Repr[String]#Repr[String]#Repr[String]#Repr[String]#Repr[String]#Repr[String]#Repr[String]#Repr[String]#Repr[String]#Repr[String]#Repr[String]
+  ) = {
+    f.map
+  }
+}
diff --git a/test/files/run/settings-parse.scala b/test/files/run/settings-parse.scala
index 2754feb972..8d83caf68f 100644
--- a/test/files/run/settings-parse.scala
+++ b/test/files/run/settings-parse.scala
@@ -3,9 +3,8 @@ import scala.language.postfixOps
 import scala.tools.nsc._
 
 object Test {
-  val tokens        = List("", "-deprecation", "foo.scala")
-  val subsets       = tokens.toSet.subsets.toList
-  val permutations0 = subsets.flatMap(_.toList.permutations).distinct
+  val tokens        = "" :: "-deprecation" :: "foo.scala" :: Nil
+  val permutations0 = tokens.toSet.subsets.flatMap(_.toList.permutations).toList.distinct
 
   def runWithCp(cp: String) = {
     val permutations = permutations0 flatMap ("-cp CPTOKEN" :: _ permutations)
diff --git a/test/junit/scala/util/RandomTest.scala b/test/junit/scala/util/RandomTest.scala
new file mode 100644
index 0000000000..32959675ee
--- /dev/null
+++ b/test/junit/scala/util/RandomTest.scala
@@ -0,0 +1,15 @@
+package scala.util
+
+import org.junit.{ Assert, Test }
+
+class RandomTest {
+  // Test for SI-9059
+  @Test def testAlphanumeric: Unit = {
+    def isAlphaNum(c: Char) = (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9')
+
+    val items = Random.alphanumeric.take(100000)
+    for (c <- items) {
+      Assert.assertTrue(s"$c should be alphanumeric", isAlphaNum(c))
+    }
+  }
+}