Merge pull request #669 from dotty-staging/fix-patmat-seq

Fix sequence matching.

Author: odersky

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

@@ -189,7 +189,8 @@ trait TreeInfo[T >: Untyped <: Type] { self: Trees.Instance[T] =>
 
   /** Is this argument node of the form <expr> : _* ?
    */
-  def isWildcardStarArg(tree: untpd.Tree)(implicit ctx: Context): Boolean = unsplice(tree) match {
+  def isWildcardStarArg(tree: Tree)(implicit ctx: Context): Boolean = unbind(tree) match {
+    case Typed(Ident(nme.WILDCARD_STAR), _) => true
     case Typed(_, Ident(tpnme.WILDCARD_STAR)) => true
     case Typed(_, tpt: TypeTree) => tpt.hasType && tpt.tpe.isRepeatedParam
     case _ => false

src/dotty/tools/dotc/transform/PatternMatcher.scala

@@ -136,7 +136,7 @@ class PatternMatcher extends MiniPhaseTransform with DenotTransformer {thisTrans
         def callDirect   = tgt.select(nme.drop).appliedTo(Literal(Constant(n)))
         def callRuntime  = ref(defn.traversableDropMethod).appliedTo(tgt, Literal(Constant(n)))
 
-        def needsRuntime = tgt.tpe derivesFrom defn.SeqClass /*typeOfMemberNamedDrop(tgt.tpe) == NoType*/
+        def needsRuntime = !(tgt.tpe derivesFrom defn.SeqClass) /*typeOfMemberNamedDrop(tgt.tpe) == NoType*/
 
         if (needsRuntime) callRuntime else callDirect
       }

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

@@ -377,10 +377,11 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
     }
     tree.expr match {
       case id: untpd.Ident if (ctx.mode is Mode.Pattern) && isVarPattern(id) =>
-        if (id.name == nme.WILDCARD) regularTyped(isWildcard = true)
+        if (id.name == nme.WILDCARD || id.name == nme.WILDCARD_STAR) regularTyped(isWildcard = true)
         else {
           import untpd._
-          typed(Bind(id.name, Typed(Ident(nme.WILDCARD), tree.tpt)).withPos(id.pos), pt)
+          val name = if (untpd.isWildcardStarArg(tree)) nme.WILDCARD_STAR else nme.WILDCARD
+          typed(Bind(id.name, Typed(Ident(name), tree.tpt)).withPos(id.pos), pt)
         }
       case _ =>
         if (untpd.isWildcardStarArg(tree))