Merge pull request #1981 from retronym/backport/1187

[backport] SI-3577 BoundedWildcardType handling

4 files changed, 42 insertions, 7 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 969bb8aceb..96e480cc84 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -905,13 +905,15 @@ abstract class RefChecks extends InfoTransform with scala.reflect.internal.trans
          *  the type occurs itself at variance position given by `variance`
          */
         def validateVariance(tp: Type, variance: Int): Unit = tp match {
-          case ErrorType => ;
-          case WildcardType => ;
-          case NoType => ;
-          case NoPrefix => ;
-          case ThisType(_) => ;
-          case ConstantType(_) => ;
-          // case DeBruijnIndex(_, _) => ;
+          case ErrorType =>
+          case WildcardType =>
+          case BoundedWildcardType(bounds) =>
+            validateVariance(bounds, variance)
+          case NoType =>
+          case NoPrefix =>
+          case ThisType(_) =>
+          case ConstantType(_) =>
+          // case DeBruijnIndex(_, _) =>
           case SingleType(pre, sym) =>
             validateVariance(pre, variance)
           case TypeRef(pre, sym, args) =>
diff --git a/src/compiler/scala/tools/nsc/typechecker/Variances.scala b/src/compiler/scala/tools/nsc/typechecker/Variances.scala
index 7d97b0c782..ea436a71fb 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Variances.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Variances.scala
@@ -67,6 +67,8 @@ trait Variances {
   def varianceInType(tp: Type)(tparam: Symbol): Int = tp match {
     case ErrorType | WildcardType | NoType | NoPrefix | ThisType(_) | ConstantType(_) =>
       VARIANCES
+    case BoundedWildcardType(bounds) =>
+      varianceInType(bounds)(tparam)
     case SingleType(pre, sym) =>
       varianceInType(pre)(tparam)
     case TypeRef(pre, sym, args) =>
diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala
index dbc00edb1a..d0c9b8dd03 100644
--- a/src/reflect/scala/reflect/internal/Types.scala
+++ b/src/reflect/scala/reflect/internal/Types.scala
@@ -22,6 +22,8 @@ import util.ThreeValues._
     // internal: error
   case WildcardType =>
     // internal: unknown
+  case BoundedWildcardType(bounds) =>
+    // internal: unknown
   case NoType =>
   case NoPrefix =>
   case ThisType(sym) =>
diff --git a/test/files/pos/t3577.scala b/test/files/pos/t3577.scala
new file mode 100644
index 0000000000..80a280f67a
--- /dev/null
+++ b/test/files/pos/t3577.scala
@@ -0,0 +1,29 @@
+case class Check[A](val value: A)
+
+case class C2(checks: Check[_]*);
+
+object C {
+  def m(x : C2): Any = (null: Any) match {
+    case C2(_, rest @ _*) => {
+      rest.map(_.value)
+    }
+  }
+}
+
+///////////////////
+
+object Container {
+  trait Exp[+T]
+  abstract class FuncExp[-S, +T]
+
+  sealed abstract class FoundNode[T, Repr] {
+    def optimize[TupleT, U, That](parentNode: FlatMap[T, Repr, U, That]): Any
+    def optimize2[TupleT, U, That](parentNode: Any): Any
+  }
+
+  class FlatMap[T, Repr, U, That]
+
+  val Seq(fn: FoundNode[t, repr]) = Seq[FoundNode[_, _]]()
+  fn.optimize(null)    // was: scala.MatchError: ? (of class BoundedWildcardType) @ Variances#varianceInType
+  fn.optimize2(null) // was: fatal error: bad type: ?(class scala.reflect.internal.Types$BoundedWildcardType) @ Pickle.putType
+}