Fix eta lifting for functions with vararg parameters.

2 files changed, 7 insertions, 6 deletions

diff --git a/src/dotty/tools/dotc/ast/untpd.scala b/src/dotty/tools/dotc/ast/untpd.scala
index 28a3cf1ff..85052a4da 100644
--- a/src/dotty/tools/dotc/ast/untpd.scala
+++ b/src/dotty/tools/dotc/ast/untpd.scala
@@ -234,12 +234,13 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
    *  parameter, the reference will be a repeated argument.
    */
   def refOfDef(tree: MemberDef)(implicit ctx: Context) = tree match {
-    case ValDef(_, PostfixOp(_, nme.raw.STAR), _) =>
-      Typed(Ident(tree.name), Ident(tpnme.WILDCARD_STAR))
-    case _ =>
-      Ident(tree.name)
+    case ValDef(_, PostfixOp(_, nme.raw.STAR), _) => repeated(Ident(tree.name))
+    case _ => Ident(tree.name)
   }
 
+  /** A repeated argument such as `arg: _*` */
+  def repeated(arg: Tree)(implicit ctx: Context) = Typed(arg, Ident(tpnme.WILDCARD_STAR))
+
 // ------- Decorators -------------------------------------------------
 
   implicit class UntypedTreeDecorator(val self: Tree) extends AnyVal {
diff --git a/src/dotty/tools/dotc/typer/EtaExpansion.scala b/src/dotty/tools/dotc/typer/EtaExpansion.scala
index 89415024e..42fcd94a4 100644
--- a/src/dotty/tools/dotc/typer/EtaExpansion.scala
+++ b/src/dotty/tools/dotc/typer/EtaExpansion.scala
@@ -141,8 +141,8 @@ object EtaExpansion {
       else mt.paramTypes map TypeTree
     val params = (mt.paramNames, paramTypes).zipped.map((name, tpe) =>
       ValDef(name, TypeTree(tpe), EmptyTree).withFlags(Synthetic | Param).withPos(tree.pos))
-    val ids = mt.paramNames map (name =>
-      Ident(name).withPos(tree.pos))
+    var ids: List[Tree] = mt.paramNames map (name => Ident(name).withPos(tree.pos))
+    if (mt.paramTypes.last.isRepeatedParam)ids = ids.init :+ repeated(ids.last)
     val body = Apply(lifted, ids)
     val fn = untpd.Function(params, body)
     if (defs.nonEmpty) untpd.Block(defs.toList map untpd.TypedSplice, fn) else fn