Fix #167

Can handle now vararg arguments in patterns.

Author: odersky

src/dotty/tools/dotc/ast/Desugar.scala

@@ -860,7 +860,7 @@ object desugar {
       case tree @ Bind(_, tree1) =>
         add(tree, TypeTree())
         collect(tree1)
-      case Typed(id: Ident, t) if isVarPattern(id) && id.name != nme.WILDCARD =>
+      case Typed(id: Ident, t) if isVarPattern(id) && id.name != nme.WILDCARD && !isWildcardStarArg(tree) =>
         add(id, t)
       case id: Ident if isVarPattern(id) && id.name != nme.WILDCARD =>
         add(id, TypeTree())

src/dotty/tools/dotc/typer/Typer.scala

@@ -325,7 +325,11 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
 
   def typedTyped(tree: untpd.Typed, pt: Type)(implicit ctx: Context): Tree = track("typedTyped") {
     def regularTyped(isWildcard: Boolean) = {
-      val tpt1 = typedType(tree.tpt)
+      val tpt1 =
+        if (untpd.isWildcardStarArg(tree))
+          TypeTree(defn.SeqClass.typeRef.appliedTo(pt :: Nil))
+        else
+          typedType(tree.tpt)
       val expr1 =
         if (isWildcard) tree.expr withType tpt1.tpe
         else typed(tree.expr, tpt1.tpe)
@@ -336,7 +340,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         if (id.name == nme.WILDCARD) regularTyped(isWildcard = true)
         else {
           import untpd._
-          typed(Bind(id.name, Typed(Ident(nme.WILDCARD), tree.tpt)).withPos(id.pos))
+          typed(Bind(id.name, Typed(Ident(nme.WILDCARD), tree.tpt)).withPos(id.pos), pt)
         }
       case _ =>
         if (untpd.isWildcardStarArg(tree))

tests/pos/vararg-pattern.scala

@@ -0,0 +1,12 @@
+object Test {
+
+  List(1, 2, 3, 4) match {
+    case List(1, 2, xs: _*) =>
+      val ys: Seq[Int] = xs
+      println(ys)
+  }
+  val List(1, 2, x: _*) = List(1, 2, 3, 4)
+
+}
+
+