Merge pull request #1901 from paulp/pr/dealias-plus-annotations

dealiasing and annotations

1 files changed, 48 insertions, 5 deletions

diff --git a/test/pending/pos/those-kinds-are-high.scala b/test/pending/pos/those-kinds-are-high.scala
index 434e64cefb..78367cb746 100644
--- a/test/pending/pos/those-kinds-are-high.scala
+++ b/test/pending/pos/those-kinds-are-high.scala
@@ -4,18 +4,18 @@ class A {
 
   class C1[T] extends Template[C1] with Container[T]
   class C2[T] extends Template[C2] with Container[T]
-  
+
   /** Target expression:
    *    List(new C1[String], new C2[String])
    */
-    
+
   // Here's what would ideally be inferred.
   //
   // scala> :type List[Template[Container] with Container[String]](new C1[String], new C2[String])
   // List[Template[Container] with Container[java.lang.String]]
   //
   // Here's what it does infer.
-  // 
+  //
   // scala> :type List(new C1[String], new C2[String])
   // <console>:8: error: type mismatch;
   //  found   : C1[String]
@@ -43,11 +43,54 @@ class A {
   //   def fFail = List(new C1[String], new C2[String])
   //                                    ^
   // two errors found
-  
+
   /** Working version explicitly typed.
    */
   def fExplicit = List[Template[Container] with Container[String]](new C1[String], new C2[String])
-  
+
   // nope
   def fFail = List(new C1[String], new C2[String])
 }
+
+
+trait Other {
+  trait GenBar[+A]
+  trait Bar[+A] extends GenBar[A]
+  trait Templ[+A, +CC[X] <: GenBar[X]]
+
+  abstract class CC1[+A] extends Templ[A, CC1] with Bar[A]
+  abstract class CC2[+A] extends Templ[A, CC2] with Bar[A]
+
+  // Compiles
+  class A1 {
+    abstract class BarFactory[CC[X] <: Bar[X]]
+
+    def f(x: Boolean) = if (x) (null: BarFactory[CC1]) else (null: BarFactory[CC2])
+  }
+
+  // Fails - only difference is CC covariant.
+  class A2 {
+    abstract class BarFactory[+CC[X] <: Bar[X]]
+
+    def f(x: Boolean) = if (x) (null: BarFactory[CC1]) else (null: BarFactory[CC2])
+    // c.scala:23: error: kinds of the type arguments (Bar with Templ[Any,Bar]) do not conform to the expected kinds of the type parameters (type CC) in class BarFactory.
+    // Bar with Templ[Any,Bar]'s type parameters do not match type CC's expected parameters:
+    // <empty> has no type parameters, but type CC has one
+    //   def f(x: Boolean) = if (x) (null: BarFactory[CC1]) else (null: BarFactory[CC2])
+    //       ^
+    // one error found
+  }
+
+  // Compiles - CC contravariant.
+  class A3 {
+    abstract class BarFactory[-CC[X] <: Bar[X]] // with Templ[X, CC]]
+
+    def f(x: Boolean) = if (x) (null: BarFactory[CC1]) else (null: BarFactory[CC2])
+    // c.scala:23: error: kinds of the type arguments (Bar with Templ[Any,Bar]) do not conform to the expected kinds of the type parameters (type CC) in class BarFactory.
+    // Bar with Templ[Any,Bar]'s type parameters do not match type CC's expected parameters:
+    // <empty> has no type parameters, but type CC has one
+    //   def f(x: Boolean) = if (x) (null: BarFactory[CC1]) else (null: BarFactory[CC2])
+    //       ^
+    // one error found
+  }
+}