Merge pull request #1913 from dotty-staging/fix-#1750

Fix #1750: Alternative fix for cyclic references due to illegal class overrides

6 files changed, 28 insertions, 9 deletions

diff --git a/tests/neg/customArgs/overrideClass.scala b/tests/neg/customArgs/overrideClass.scala
index 803d97dd9..431b846d9 100644
--- a/tests/neg/customArgs/overrideClass.scala
+++ b/tests/neg/customArgs/overrideClass.scala
@@ -8,8 +8,7 @@
   }
   trait FooB extends FooA {
     type A <: Ax;
-    trait Ax extends super.Ax { def xxx : Int; } // error: cyclic inheritance: trait Ax extends itself
-                                                 // (Note that inheriting a class of the same name is no longer allowed)
+    trait Ax extends super.Ax { def xxx : Int; } // error: cyclic inheritance: trait Ax extends itself) // error: class definitions cannot be overridden
     abstract class InnerB extends InnerA {
       // type B <: A;
       val a : A = doB;
diff --git a/tests/neg/i1750.scala b/tests/neg/i1750.scala
new file mode 100644
index 000000000..a2ebe8f2b
--- /dev/null
+++ b/tests/neg/i1750.scala
@@ -0,0 +1,12 @@
+trait Lang1 {
+  trait Exp
+  trait Visitor { def f(left: Exp): Unit }
+  class Eval1 extends Visitor { self =>
+    def f(left: Exp) = ()
+  }
+}
+trait Lang2 extends Lang1 {
+  class Visitor extends Eval1 { Visitor => // error: classes cannot be overridden
+  }
+}
+
diff --git a/tests/neg/i1750a.scala b/tests/neg/i1750a.scala
new file mode 100644
index 000000000..cbb5bec95
--- /dev/null
+++ b/tests/neg/i1750a.scala
@@ -0,0 +1,13 @@
+trait Lang1 {
+  trait Exp
+  trait Visitor { def f(left: Exp): Unit }
+  class Eval1 extends Visitor { self =>
+    def f(left: Exp) = ()
+  }
+}
+trait Lang3 { self: Lang1 =>
+  class Visitor extends Eval1 { Visitor => // error: classes cannot be overridden
+  }
+}
+trait Lang4 extends Lang1 with Lang3
+
diff --git a/tests/neg/i1806.scala b/tests/neg/i1806.scala
index 7e5e132f2..199ab4791 100644
--- a/tests/neg/i1806.scala
+++ b/tests/neg/i1806.scala
@@ -2,6 +2,6 @@ trait A {
   class Inner
  }
 trait B extends A {
-  class Inner extends super.Inner // error
+  class Inner extends super.Inner // error // error
 }
 
diff --git a/tests/neg/overrides.scala b/tests/neg/overrides.scala
index 81a93a7a2..149220bd5 100644
--- a/tests/neg/overrides.scala
+++ b/tests/neg/overrides.scala
@@ -34,11 +34,6 @@ package p2 { // all being in the same package compiles fine
     }
   }
 
-  abstract class T3 extends T2 {
-    class A {   // error: classes cannot be overridden
-      bug()
-    }
-  }
 }
 
 class A[T] {
diff --git a/tests/neg/t7278.scala b/tests/neg/t7278.scala
index 643a3c858..7b13535f0 100644
--- a/tests/neg/t7278.scala
+++ b/tests/neg/t7278.scala
@@ -1,5 +1,5 @@
 class A { class E }
-class B extends A { class E }
+class B extends A { class EB }
 trait C { type E = Int }
 trait D { type E = String }
 trait EC { type E }