Merge remote-tracking branches 'retronym/ticket/5072' and 'odersky/topic/t5120' into develop

3 files changed, 43 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 0fbde03e97..216ad6cd4c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2838,9 +2838,22 @@ trait Typers extends Modes with Adaptations with PatMatVirtualiser {
     def packSymbols(hidden: List[Symbol], tp: Type): Type =
       if (hidden.isEmpty) tp
       else existentialTransform(hidden, tp)(existentialAbstraction)
+      
+    def isReferencedFrom(ctx: Context, sym: Symbol): Boolean =
+      ctx.owner.isTerm && 
+      (ctx.scope.exists { dcl => dcl.isInitialized && (dcl.info contains sym) }) || 
+      {
+        var ctx1 = ctx.outer
+        while ((ctx1 != NoContext) && (ctx1.scope eq ctx.scope)) ctx1 = ctx1.outer
+        (ctx1 != NoContext) && isReferencedFrom(ctx1, sym)
+      }
 
     def isCapturedExistential(sym: Symbol) =
-      sym hasAllFlags (EXISTENTIAL | CAPTURED)  // todo refine this
+      (sym hasAllFlags (EXISTENTIAL | CAPTURED)) && {
+      val start = startTimer(isReferencedNanos)
+      try !isReferencedFrom(context, sym)
+      finally stopTimer(isReferencedNanos, start)
+    }
 
     def packCaptured(tpe: Type): Type = {
       val captured = mutable.Set[Symbol]()
diff --git a/src/compiler/scala/tools/nsc/util/Statistics.scala b/src/compiler/scala/tools/nsc/util/Statistics.scala
index 27239b9b9f..f7c27dceb5 100644
--- a/src/compiler/scala/tools/nsc/util/Statistics.scala
+++ b/src/compiler/scala/tools/nsc/util/Statistics.scala
@@ -20,7 +20,7 @@ class Statistics extends scala.reflect.internal.util.Statistics {
   val typedSelectCount = new Counter
   val typerNanos = new Timer
   val classReadNanos = new Timer
-
+  
   val failedApplyNanos = new Timer
   val failedOpEqNanos = new Timer
   val failedSilentNanos = new Timer
@@ -48,6 +48,7 @@ class Statistics extends scala.reflect.internal.util.Statistics {
   val subtypeImprovCount = new SubCounter(subtypeCount)
   val subtypeETNanos = new Timer
   val matchesPtNanos = new Timer
+  val isReferencedNanos = new Timer
   val ctr1 = new Counter
   val ctr2 = new Counter
   val ctr3 = new Counter
@@ -137,6 +138,7 @@ abstract class StatisticsInfo {
         inform("time spent in failed     : "+showRelTyper(failedSilentNanos))
         inform("       failed apply      : "+showRelTyper(failedApplyNanos))
         inform("       failed op=        : "+showRelTyper(failedOpEqNanos))
+        inform("time spent ref scanning  : "+showRelTyper(isReferencedNanos))
         inform("micros by tree node      : "+showCounts(microsByType))
         inform("#visits by tree node     : "+showCounts(visitsByType))
         val average = new ClassCounts
diff --git a/test/files/pos/t5120.scala b/test/files/pos/t5120.scala
new file mode 100644
index 0000000000..2c193d129d
--- /dev/null
+++ b/test/files/pos/t5120.scala
@@ -0,0 +1,26 @@
+// An example extracted from SBT by Iulian 
+// that showed that the previous fix to t5120 
+// was too strict.
+class Test {
+  class ScopedKey[T]
+  class Value[T]
+
+  class Compiled[T](val settings: Seq[Pair[T]])
+  
+  case class Pair[T](k: ScopedKey[T], v: ScopedKey[T])
+
+  def transform[T](x: T) = x
+
+  def test(compiledSettings: Seq[Compiled[_]]) =  {
+    compiledSettings flatMap { cs => // cd: Compiled[_] in both versions
+      (cs.settings  map { s =>       // cs.settings: Seq[Compiled[$1]] in trunk, Seq[Compiled[$1]] forSome $1 in 2.9.1
+                                     // s: Pair[$1] in trunk, Pair[$1] in 2.9.1
+        val t = transform(s.v)       // t: ScopedKey[_] in trunk, ScopedKey[$1] in 2.9.1
+        foo(s.k, t)
+        t
+     }) : Seq[ScopedKey[_]]
+    }
+  }
+
+  def foo[T](x: ScopedKey[T], v: ScopedKey[T]) {}
+}