Fix substDealias

substDealias did not follow aliases when the prefix of a typeref changed
under substitution. This was exhibited by a bug in extensionMethods which was
first discovered in CollectionStrawMan6 and was minimized in extmethods.

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/pos/extmethods.scala b/tests/pos/extmethods.scala
index cac1c4ec1..fe95a1c79 100644
--- a/tests/pos/extmethods.scala
+++ b/tests/pos/extmethods.scala
@@ -9,3 +9,14 @@ class Foo[+A <: AnyRef](val xs: List[A]) extends AnyVal {
   def baz[B >: A](x: B): List[B] = ???
 }
 
+object CollectionStrawMan {
+  import collection.mutable.ArrayBuffer
+  import reflect.ClassTag
+
+  implicit class ArrayOps[A](val xs: Array[A]) extends AnyVal {
+
+    def elemTag: ClassTag[A] = ClassTag(xs.getClass.getComponentType)
+
+    protected[this] def newBuilder = new ArrayBuffer[A].mapResult(_.toArray(elemTag))
+  }
+}