Add test case

Author: odersky

test/dotc/scala-collections.whitelist

@@ -184,7 +184,7 @@
 ./scala-scala/src/library/scala/collection/SortedSetLike.scala
 ./scala-scala/src/library/scala/collection/Traversable.scala
 
-# https://github.com/lampepfl/dotty/issues/938
+# https://github.com/lampepfl/dotty/issues/938 (but relies also on #937 being fixed)
 #./scala-scala/src/library/scala/collection/TraversableLike.scala
 
 ./scala-scala/src/library/scala/collection/TraversableProxy.scala

tests/pos/i938.scala

@@ -0,0 +1,21 @@
+object Test {
+  import scala.collection._
+
+  trait T {
+    def f() : Unit
+  }
+
+  def view = new T {
+    def f() = ()
+  }
+
+  trait TLike[+A, RR] { self =>
+
+    def repr: RR = ???
+
+    def view2 = new TraversableView[A, RR] {
+      protected lazy val underlying = self.repr
+      override def foreach[U](f: A => U): Unit = ???
+    }
+  }
+}