add tests

Author: liufengyun

tests/neg/i5083.scala

@@ -0,0 +1,25 @@
+class A(a: Int) {
+  abstract class X {
+    def f: Int
+    val x = a + f      // NPE: the outer for `Y` is not yet set
+  }
+
+  trait Y {
+    val y = a
+    def f: Int = A.this.a      // NPE: the outer for `Y` is not yet set
+  }
+
+  trait Z(val o: A) extends o.Y {  // error
+    val z = a
+  }
+
+  class B extends X with Z(new A(4))
+}
+
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val a = new A(3)
+    new a.B
+  }
+}

tests/neg/i5083b.scala

@@ -0,0 +1,15 @@
+class A(a: Int) {
+  class X {
+    val x = a
+  }
+
+  trait Y {
+    val y = a
+  }
+
+  val z: Z = ???
+
+  trait Z(val o: A) extends z.o.Y   // error: cyclic reference `z`
+
+  class B extends X with Z(new A(4))
+}