1 files changed, 65 insertions, 0 deletions
diff --git a/test/test/ContravariantTrees.scala b/test/test/ContravariantTrees.scala
new file mode 100644
index 000000000..5fd45bce2
--- /dev/null
+++ b/test/test/ContravariantTrees.scala
@@ -0,0 +1,65 @@
+package test
+
+import language.higherKinds
+import dotty.tools.dotc.core._
+import Flags._, Names._, StdNames._
+import annotation.unchecked.uncheckedVariance
+
+object ContravariantTrees {
+
+  type Untyped = Null
+
+  case class Modifiers[-T >: Untyped] (
+    flags: FlagSet = EmptyFlags,
+    privateWithin: TypeName = tpnme.EMPTY,
+    annotations: List[Tree[T]] = Nil) {
+
+    def is(fs: FlagSet): Boolean = flags is fs
+    def is(fc: FlagConjunction): Boolean = flags is fc
+
+    def | (fs: FlagSet): Modifiers[T] = withFlags(flags | fs)
+    def & (fs: FlagSet): Modifiers[T] = withFlags(flags & fs)
+    def &~(fs: FlagSet): Modifiers[T] = withFlags(flags &~ fs)
+
+    def toTypeFlags: Modifiers[T] = withFlags(flags.toTypeFlags)
+    def toTermFlags: Modifiers[T] = withFlags(flags.toTermFlags)
+
+    private def withFlags(flags: FlagSet) =
+      if (this.flags == flags) this
+      else copy(flags = flags)
+
+    def withPrivateWithin(pw: TypeName) =
+      if (pw.isEmpty) this
+      else copy(privateWithin = pw)
+
+    def hasFlags = flags != EmptyFlags
+    def hasAnnotations = annotations.nonEmpty
+    def hasPrivateWithin = privateWithin != tpnme.EMPTY
+  }
+
+  abstract class Tree[-T >: Untyped] {
+    private[this] var myTpe: T = _
+    private def setMyTpe(tpe: T) = myTpe = tpe
+
+    def tpe: T @uncheckedVariance = {
+      if (myTpe == null) throw new Error()
+      myTpe
+    }
+  }
+
+  trait TermTree[-T >: Untyped] extends Tree[T] {
+    type ThisTree[T >: Untyped] <: TermTree[T]
+  }
+
+  case class Select[-T >: Untyped](qualifier: Tree[T], name: Name)
+    extends TermTree[T] {
+    type ThisTree[T >: Untyped] = Select[T]
+  }
+
+    /** mods def name[tparams](vparams_1)...(vparams_n): tpt = rhs */
+  case class DefDef[-T >: Untyped](mods: Modifiers[T], name: TermName, tparams: List[Tree[T]], vparamss: List[List[Tree[T]]], tpt: Tree[T], rhs: Tree[T])
+    extends Tree[T] {
+    type ThisTree[T >: Untyped] = DefDef[T]
+  }
+
+}
+\ No newline at end of file