Pattern matching virtualization now guarded by -Yvirtpatmat.

6 files changed, 9 insertions, 2 deletions

diff --git a/bincompat-forward.whitelist.conf b/bincompat-forward.whitelist.conf
index 541268e50e..aebd2c8d1b 100644
--- a/bincompat-forward.whitelist.conf
+++ b/bincompat-forward.whitelist.conf
@@ -20,6 +20,10 @@ filter {
     {
       matchName="scala.sys.process.ProcessImpl#CompoundProcess.futureThread"
       problemName=DirectMissingMethodProblem
+    },
+    {
+      matchName="scala.reflect.runtime.Settings.Yvirtpatmat"
+      problemName=DirectMissingMethodProblem
     }
   ]
 }
diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 5eb99e0d98..a3b9df1518 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -215,6 +215,7 @@ trait ScalaSettings extends AbsScalaSettings
   val inferByName     = BooleanSetting    ("-Yinfer-by-name", "Allow inference of by-name types. This is a temporary option to ease transition. See SI-7899.").withDeprecationMessage(removalIn212)
   val YdisableFlatCpCaching  = BooleanSetting    ("-YdisableFlatCpCaching", "Do not cache flat classpath representation of classpath elements from jars across compiler instances.")
   val YpartialUnification = BooleanSetting ("-Ypartial-unification", "Enable partial unification in type constructor inference")
+  val Yvirtpatmat     = BooleanSetting    ("-Yvirtpatmat", "Enable pattern matcher virtualization")
 
   val exposeEmptyPackage = BooleanSetting ("-Yexpose-empty-package", "Internal only: expose the empty package.").internalOnly()
   val Ydelambdafy        = ChoiceSetting  ("-Ydelambdafy", "strategy", "Strategy used for translating lambdas into JVM code.", List("inline", "method"), "method")
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index cca6f280e3..c89a410334 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2555,7 +2555,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
 
       // TODO: add fallback __match sentinel to predef
       val matchStrategy: Tree =
-        if (!(settings.Xexperimental && context.isNameInScope(vpmName._match))) null    // fast path, avoiding the next line if there's no __match to be seen
+        if (!(settings.Yvirtpatmat && context.isNameInScope(vpmName._match))) null    // fast path, avoiding the next line if there's no __match to be seen
         else newTyper(context.makeImplicit(reportAmbiguousErrors = false)).silent(_.typed(Ident(vpmName._match)), reportAmbiguousErrors = false) orElse (_ => null)
 
       if (matchStrategy ne null) // virtualize
diff --git a/src/reflect/scala/reflect/internal/settings/MutableSettings.scala b/src/reflect/scala/reflect/internal/settings/MutableSettings.scala
index 5a2c802476..ab933ae617 100644
--- a/src/reflect/scala/reflect/internal/settings/MutableSettings.scala
+++ b/src/reflect/scala/reflect/internal/settings/MutableSettings.scala
@@ -54,6 +54,7 @@ abstract class MutableSettings extends AbsSettings {
   def uniqid: BooleanSetting
   def verbose: BooleanSetting
   def YpartialUnification: BooleanSetting
+  def Yvirtpatmat: BooleanSetting
 
   def Yrecursion: IntSetting
   def maxClassfileName: IntSetting
diff --git a/src/reflect/scala/reflect/runtime/Settings.scala b/src/reflect/scala/reflect/runtime/Settings.scala
index 3b33f089e1..2d8bacd3b2 100644
--- a/src/reflect/scala/reflect/runtime/Settings.scala
+++ b/src/reflect/scala/reflect/runtime/Settings.scala
@@ -48,6 +48,7 @@ private[reflect] class Settings extends MutableSettings {
   val uniqid            = new BooleanSetting(false)
   val verbose           = new BooleanSetting(false)
   val YpartialUnification = new BooleanSetting(false)
+  val Yvirtpatmat       = new BooleanSetting(false)
 
   val Yrecursion        = new IntSetting(0)
   val maxClassfileName  = new IntSetting(255)
diff --git a/test/files/run/virtpatmat_staging.flags b/test/files/run/virtpatmat_staging.flags
index 0a22f7c729..bec3aa96e9 100644
--- a/test/files/run/virtpatmat_staging.flags
+++ b/test/files/run/virtpatmat_staging.flags
@@ -1,2 +1,2 @@
 -Yrangepos:false
--Xexperimental
+-Yvirtpatmat