Fix #540 - unbounded array test for wildcard array arguments

Arrays with wildcard arguments such as Array[_ <: Foo] where Foo is a
universal trait are now diagnosed as unbounded generic arrays and are
erased to Object.

2 files changed, 9 insertions, 1 deletions

diff --git a/src/dotty/tools/dotc/core/TypeErasure.scala b/src/dotty/tools/dotc/core/TypeErasure.scala
index 71146bd4e..f499e2ece 100644
--- a/src/dotty/tools/dotc/core/TypeErasure.scala
+++ b/src/dotty/tools/dotc/core/TypeErasure.scala
@@ -182,13 +182,14 @@ object TypeErasure {
     case tp: PolyParam =>
       !tp.derivesFrom(defn.ObjectClass) &&
       !tp.binder.resultType.isInstanceOf[JavaMethodType]
+    case tp: TypeAlias => isUnboundedGeneric(tp.alias)
+    case tp: TypeBounds => !tp.hi.derivesFrom(defn.ObjectClass)
     case tp: TypeProxy => isUnboundedGeneric(tp.underlying)
     case tp: AndType => isUnboundedGeneric(tp.tp1) || isUnboundedGeneric(tp.tp2)
     case tp: OrType => isUnboundedGeneric(tp.tp1) && isUnboundedGeneric(tp.tp2)
     case _ => false
   }
 
-
   /** The erased least upper bound is computed as follows
    *  - if both argument are arrays, an array of the lub of the element types
    *  - if one argument is an array, Object
@@ -365,6 +366,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
     val defn.ArrayType(elemtp) = tp
     def arrayErasure(tpToErase: Type) =
       erasureFn(isJava, semiEraseVCs = false, isConstructor, wildcardOK)(tpToErase)
+    println(s"erase array, elemtp = $elemtp")
     if (elemtp derivesFrom defn.NullClass) JavaArrayType(defn.ObjectType)
     else if (isUnboundedGeneric(elemtp)) defn.ObjectType
     else JavaArrayType(arrayErasure(elemtp))
diff --git a/tests/pos/i540.scala b/tests/pos/i540.scala
new file mode 100644
index 000000000..b7540ab2c
--- /dev/null
+++ b/tests/pos/i540.scala
@@ -0,0 +1,6 @@
+trait Foo extends Any
+
+object Univ {
+  def univ[T <: Foo](x: Array[T]) = {}
+  def univ2(x: Array[_ <: Foo]) = {}
+}