Fix for crasher during type inference.

Well, "fix" is pretty generous, how about "workaround".
It does seem to do the job.  Closes SI-4070, review by @moors.

1 files changed, 35 insertions, 0 deletions

diff --git a/test/files/pos/t4070b.scala b/test/files/pos/t4070b.scala
new file mode 100644
index 0000000000..36d03de80c
--- /dev/null
+++ b/test/files/pos/t4070b.scala
@@ -0,0 +1,35 @@
+package a {
+  abstract class DeliteOp[B]
+  abstract class DeliteCollection[A]
+  abstract class Exp[T] { def Type: T }
+
+  trait DeliteOpMap[A,B,C[X] <: DeliteCollection[X]] extends DeliteOp[C[B]] {
+    val in: Exp[C[A]]
+    val func: Exp[B]
+    val alloc: Exp[C[B]]
+  }
+
+  object Test {
+    def f(x: DeliteOp[_]) = x match {
+      case map: DeliteOpMap[_,_,_] => map.alloc.Type
+    }
+  }
+}
+
+package b {
+  object Test {
+    def f(x: DeliteOp[_]) = x match {
+      case map: DeliteOpMap[_,_,_] => map.alloc.Type
+    }
+  }
+
+  abstract class DeliteOp[B]
+  abstract class DeliteCollection[A]
+  abstract class Exp[T] { def Type: T }
+
+  trait DeliteOpMap[A,B,C[X] <: DeliteCollection[X]] extends DeliteOp[C[B]] {
+    val in: Exp[C[A]]
+    val func: Exp[B]
+    val alloc: Exp[C[B]]
+  }
+}
\ No newline at end of file