From fe52cb070db7321ab515c4758daa4f9bd187608a Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Mon, 10 Aug 2009 15:28:12 +0000
Subject: Fixed #1642

---
 src/compiler/scala/tools/nsc/symtab/Types.scala      | 11 +++++++++++
 src/compiler/scala/tools/nsc/transform/Erasure.scala |  4 ++--
 test/files/neg/implicits.scala                       | 17 +++++++++++++++++
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/compiler/scala/tools/nsc/symtab/Types.scala b/src/compiler/scala/tools/nsc/symtab/Types.scala
index 5375f77569..c2f915e570 100644
--- a/src/compiler/scala/tools/nsc/symtab/Types.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Types.scala
@@ -191,6 +191,7 @@ trait Types {
     override def instantiateTypeParams(formals: List[Symbol], actuals: List[Type]) = underlying.instantiateTypeParams(formals, actuals)
     override def skolemizeExistential(owner: Symbol, origin: AnyRef) = underlying.skolemizeExistential(owner, origin)
     override def normalize = maybeRewrap(underlying.normalize)
+    override def dealias = maybeRewrap(underlying.dealias)
     override def cloneInfo(owner: Symbol) = maybeRewrap(underlying.cloneInfo(owner))
     override def prefixString = underlying.prefixString
     override def isComplete = underlying.isComplete
@@ -348,6 +349,9 @@ trait Types {
     /** Reduce to beta eta-long normal form. Expands type aliases and converts higher-kinded TypeRef's to PolyTypes. @M */
     def normalize = this // @MAT
 
+    /** Expands type aliases. */
+    def dealias = this
+
     /** Is this type produced as a repair for an error? */
     def isError: Boolean = typeSymbol.isError || termSymbol.isError
 
@@ -1493,6 +1497,13 @@ A type's typeSymbol should never be inspected directly.
 
     private var normalized: Type = null
 
+    override def dealias: Type =
+      if (sym.isAliasType && sym.info.typeParams.length == args.length) {
+        val xform = transform(sym.info.resultType)
+        assert(xform ne this, this)
+        xform.dealias
+      } else this
+
     def normalize0: Type =
       if (sym.isAliasType) { // beta-reduce
         if (sym.info.typeParams.length == args.length || !isHigherKinded) {
diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index 806b054ee6..4da5a59789 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -168,7 +168,7 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer with ast.
     def jsig(tp: Type): String = jsig2(false, List(), tp)
 
     def jsig2(toplevel: Boolean, tparams: List[Symbol], tp0: Type): String = {
-      val tp = tp0.normalize
+      val tp = tp0.dealias
       tp match {
         case st: SubType =>
           jsig2(toplevel, tparams, st.supertype)
@@ -251,7 +251,7 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer with ast.
     }
     if (needsJavaSig(info)) {
       try {
-        //println("Java sig of "+sym+" is "+jsig2(true, List(), sym.info))//DEBUG
+        println("Java sig of "+sym+" is "+jsig2(true, List(), sym.info))//DEBUG
         Some(jsig2(true, List(), info))
       } catch {
         case ex: UnknownSig => None
diff --git a/test/files/neg/implicits.scala b/test/files/neg/implicits.scala
index 710ffc94fc..056e0be6ca 100644
--- a/test/files/neg/implicits.scala
+++ b/test/files/neg/implicits.scala
@@ -20,3 +20,20 @@ object Test {
   def f(x: int): int = x
   f(p+1)
 }
+
+object test2 {
+  sealed trait HMap {
+    def +[T](v: T) = HSome(v,this)
+  }
+
+  final case class HSome[T, L <: HMap](head: T, tail: L) extends HMap
+
+  final object HEmpty extends HMap
+
+  val set = HEmpty + 3 + "3"
+  implicit def select[T](t: HSome[T,_]) = t.head
+  implicit def selectTail[L](t: HSome[_,L]) = t.tail
+
+  def foo(x: Int) = 3
+  foo(set)
+}
-- 
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