Typevar experimentals now default; t5729 pos -> neg.

4 files changed, 15 insertions, 19 deletions

diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index a7880c72d7..d651d523a8 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -330,8 +330,6 @@ class Global(var currentSettings: Settings, var reporter: Reporter)
   // to create it on that side.  For this one my strategy is a constant def at the file
   // where I need it, and then an override in Global with the setting.
   override protected val etaExpandKeepsStar = settings.etaExpandKeepsStar.value
-  // Here comes another one...
-  override protected val enableTypeVarExperimentals = settings.Xexperimental.value
 
   def getSourceFile(f: AbstractFile): BatchSourceFile = new BatchSourceFile(f, reader read f)
 
diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala
index f8679616d1..aa30c4a4c8 100644
--- a/src/reflect/scala/reflect/internal/Types.scala
+++ b/src/reflect/scala/reflect/internal/Types.scala
@@ -99,8 +99,6 @@ trait Types
   private final val propagateParameterBoundsToTypeVars = sys.props contains "scalac.debug.prop-constraints"
   private final val sharperSkolems = sys.props contains "scalac.experimental.sharper-skolems"
 
-  protected val enableTypeVarExperimentals = settings.Xexperimental.value
-
   /** Caching the most recent map has a 75-90% hit rate. */
   private object substTypeMapCache {
     private[this] var cached: SubstTypeMap = new SubstTypeMap(Nil, Nil)
@@ -3010,7 +3008,7 @@ trait Types
     // EXPERIMENTAL: value will not be considered unless enableTypeVarExperimentals is true
     // see SI-5729 for why this is still experimental
     private var encounteredHigherLevel = false
-    private def shouldRepackType = enableTypeVarExperimentals && encounteredHigherLevel
+    private def shouldRepackType = encounteredHigherLevel
 
     // <region name="constraint mutators + undoLog">
     // invariant: before mutating constr, save old state in undoLog
@@ -3205,7 +3203,8 @@ trait Types
         checkSubtype(tp, origin)
       else if (instValid)  // type var is already set
         checkSubtype(tp, inst)
-      else isRelatable(tp) && {
+      else {
+        trackHigherLevel(tp)
         unifySimple || unifyFull(tp) || (
           // only look harder if our gaze is oriented toward Any
           isLowerBound && (
@@ -3228,7 +3227,8 @@ trait Types
 
       if (suspended) tp =:= origin
       else if (instValid) checkIsSameType(tp)
-      else isRelatable(tp) && {
+      else {
+        trackHigherLevel(tp)
         val newInst = wildcardToTypeVarMap(tp)
         (constr isWithinBounds newInst) && {
           setInst(newInst)
@@ -3251,19 +3251,10 @@ trait Types
       case ts: TypeSkolem => ts.level > level
       case _              => false
     }
-    // side-effects encounteredHigherLevel
-    private def containsSkolemAboveLevel(tp: Type) =
-      (tp exists isSkolemAboveLevel) && { encounteredHigherLevel = true ; true }
 
-     /** Can this variable be related in a constraint to type `tp`?
-      *  This is not the case if `tp` contains type skolems whose
-      *  skolemization level is higher than the level of this variable.
-      */
-    def isRelatable(tp: Type) = (
-         shouldRepackType               // short circuit if we already know we've seen higher levels
-      || !containsSkolemAboveLevel(tp)  // side-effects tracking boolean
-      || enableTypeVarExperimentals     // -Xexperimental: always say we're relatable, track consequences
-    )
+    private def trackHigherLevel(tp: Type): Unit =
+      if(!shouldRepackType && tp.exists(isSkolemAboveLevel))
+        encounteredHigherLevel = true
 
     override def normalize: Type = (
       if (instValid) inst
diff --git a/test/files/neg/t5729.check b/test/files/neg/t5729.check
new file mode 100644
index 0000000000..10c13db8b6
--- /dev/null
+++ b/test/files/neg/t5729.check
@@ -0,0 +1,7 @@
+t5729.scala:5: error: ambiguous reference to overloaded definition,
+both method join in object Test of type [S](in: Seq[T[S]])String
+and  method join in object Test of type (in: Seq[T[_]])Int
+match argument types (Seq[T[_]])
+  join(null: Seq[T[_]])
+  ^
+one error found
diff --git a/test/files/pos/t5729.scala b/test/files/neg/t5729.scala
index 9fd9c9ffbb..9fd9c9ffbb 100644
--- a/test/files/pos/t5729.scala
+++ b/test/files/neg/t5729.scala