merge variances and Variances

Author: odersky

tests/neg/variances.scala

@@ -41,4 +41,19 @@ object Test2 extends App {
 }
 
 
+trait HasY { type Y }
+
+// These are neg-tests corresponding to the pos-test Variances.scala
+// where all the variance annotations have been inverted.
+trait Foo1[+X] { def bar[Y <: X](y: Y) = y } // error
+trait Foo2[+X] { def bar(x: HasY { type Y <: X })(y: x.Y) = y } // error
+trait Foo3[-X] { def bar[Y >: X](y: Y) = y } // error
+trait Foo4[-X] { def bar(x: HasY { type Y >: X })(y: x.Y) = y } // error
+
+// These are neg-tests corresponding to the pos-test Variances.scala
+// where all the bounds have been flipped.
+trait Foo5[-X] { def bar[Y >: X](y: Y) = y } // error
+trait Foo6[-X] { def bar(x: HasY { type Y >: X })(y: x.Y) = y } // error
+trait Foo7[+X] { def bar[Y <: X](y: Y) = y } // error
+trait Foo8[+X] { def bar(x: HasY { type Y <: X })(y: x.Y) = y } // error
 

tests/pos/variances.scala

@@ -1,3 +1,18 @@
 trait C[+T <: C[T, U], -U <: C[T, U]] {
 
 }
+trait HasY { type Y }
+
+// This works in scalac.
+trait Foo1[-X] { def bar[Y <: X](y: Y) = y }
+
+// A variant of Foo1 using a dependent method type (doesn't work using
+// scalac)
+trait Foo2[-X] { def bar(x: HasY { type Y <: X })(y: x.Y) = y }
+
+// This works in scalac.
+trait Foo3[+X] { def bar[Y >: X](y: Y) = y }
+
+// A variant of Foo3 using a dependent method type (doesn't work
+// using scalac)
+trait Foo4[+X] { def bar(x: HasY { type Y >: X })(y: x.Y) = y }