fixed #2251

2 files changed, 36 insertions, 16 deletions

diff --git a/test/files/neg/bug987.check b/test/files/neg/bug987.check
index 4cad622ab8..ec2ca621fd 100644
--- a/test/files/neg/bug987.check
+++ b/test/files/neg/bug987.check
@@ -1,19 +1,16 @@
-bug987.scala:15: error: illegal inheritance;
- class E inherits different type instances of trait B:
-B[D] and B[C]
+bug987.scala:15: error: the type intersection D with ScalaObject is malformed
+ --- because ---
+no common type instance of base types B[C], and B[D] exists.
 class E extends D
-      ^
-bug987.scala:20: error: illegal inheritance;
- class F inherits different type instances of trait B:
-B[D] and B[C]
+        ^
+bug987.scala:20: error: the type intersection D with ScalaObject is malformed
+ --- because ---
+no common type instance of base types B[C], and B[D] exists.
 class F extends D
-      ^
-bug987.scala:25: error: illegal inheritance;
- class D inherits different type instances of trait B:
-B[D] and B[C]
+        ^
+bug987.scala:25: error: the type intersection C with B[D] with ScalaObject is malformed
+ --- because ---
+no common type instance of base types B[D], and B[C] exists.
 abstract class D extends C with B[D] {}
-               ^
-bug987.scala:25: error: type arguments [D] do not conform to trait B's type parameter bounds [T <: B[T]]
-abstract class D extends C with B[D] {}
-                                ^
-four errors found
+                 ^
+three errors found
diff --git a/test/files/pos/ticket2251.scala b/test/files/pos/ticket2251.scala
new file mode 100644
index 0000000000..1e8727e999
--- /dev/null
+++ b/test/files/pos/ticket2251.scala
@@ -0,0 +1,23 @@
+// derived from pos/bug1001
+class A
+trait B[T <: B[T]] extends A
+class C extends B[C]
+class D extends B[D]
+
+class Data {
+  // force computing lub of C and D (printLubs enabled:)
+
+/*
+lub of List(D, C) at depth 2
+  lub of List(D, C) at depth 1
+    lub of List(D, C) at depth 0
+    lub of List(D, C) is A
+  lub of List(D, C) is B[_1] forSome { type _1 >: D with C <: A }
+lub of List(D, C) is B[_2] forSome { type _2 >: D with C{} <: B[_1] forSome { type _1 >: D with C{} <: A } }
+*/
+// --> result = WRONG
+
+  // should be: B[X] forSome {type X <: B[X]} -- can this be done automatically? for now, just detect f-bounded polymorphism and fall back to more coarse approximation
+
+  val data: List[A] = List(new C, new D)
+}