From 261ff3d0abea28091ce951613f440ccaabdfb7b5 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Fri, 28 Jul 2006 11:12:16 +0000
Subject: changled handling of gadts

---
 src/compiler/scala/tools/nsc/ast/TreeGen.scala     | 16 +++++--------
 .../scala/tools/nsc/transform/Erasure.scala        | 14 ++++++++++++
 test/files/pos/gadts2.scala                        | 26 ++++++++++++++++++++++
 3 files changed, 46 insertions(+), 10 deletions(-)
 create mode 100644 test/files/pos/gadts2.scala

diff --git a/src/compiler/scala/tools/nsc/ast/TreeGen.scala b/src/compiler/scala/tools/nsc/ast/TreeGen.scala
index 2f0aa072dc..4ec47829e2 100644
--- a/src/compiler/scala/tools/nsc/ast/TreeGen.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreeGen.scala
@@ -26,16 +26,12 @@ abstract class TreeGen {
       if (clazz.isRoot || clazz.isEmptyPackageClass) EmptyTree
       else mkAttributedThis(clazz)
     case SingleType(pre, sym) =>
-      if (sym.isThisSkolem) {
-        mkAttributedQualifier(ThisType(sym.deSkolemize))
-      } else {
-        val qual = mkAttributedStableRef(pre, sym)
-        qual.tpe match {
-          case MethodType(List(), restpe) =>
-            Apply(qual, List()) setType restpe
-          case _ =>
-            qual
-        }
+      val qual = mkAttributedStableRef(pre, sym)
+      qual.tpe match {
+        case MethodType(List(), restpe) =>
+          Apply(qual, List()) setType restpe
+        case _ =>
+          qual
       }
     case TypeRef(pre, sym, args) =>
       assert(phase.erasedTypes)
diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index ac5d15a985..c14e9c5c9f 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -604,6 +604,20 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer {
                   if (qual.tpe <:< targ.tpe) Typed(qual, TypeTree(qual.tpe))
                   else tree
               }
+              // todo: get rid of instanceOfErased
+              // todo: also handle the case where the singleton type is buried in a compound
+	    else if (fn.symbol == Any_isInstanceOf || fn.symbol == Any_isInstanceOfErased)
+              fn match {
+                case TypeApply(Select(qual, _), List(targ)) =>
+                  targ.tpe match {
+                    case SingleType(pre, sym) =>
+                      val cmpOp = if (targ.tpe <:< AnyValClass.tpe) Any_equals else Object_eq
+                      Apply(Select(qual, cmpOp), List(gen.mkAttributedQualifier(targ.tpe)))
+                    case _ =>
+                      tree
+                  }
+                case _ => tree
+              }
             else tree
 
           case Template(parents, body) =>
diff --git a/test/files/pos/gadts2.scala b/test/files/pos/gadts2.scala
new file mode 100644
index 0000000000..ca905c572a
--- /dev/null
+++ b/test/files/pos/gadts2.scala
@@ -0,0 +1,26 @@
+object Test{
+
+abstract class Number
+case class Int(n: int) extends Number
+case class Double(d: double) extends Number
+
+trait Term[+a]
+case class Cell[a](var x: a) extends Term[a]
+final case class NumTerm(val n: Number) extends Term[Number]
+
+
+def f[a](t:Term[a], c:Cell[a]): unit =
+  t match {
+    case NumTerm(n) => c.x = Double(1.0)
+  }
+
+
+val x:Term[Number] = NumTerm(Int(5))
+
+def main(args: Array[String]): unit = {
+  val cell = Cell[Number](Int(6))
+  Console.println(cell)
+  f[Number](new NumTerm(Int(5)), cell)
+  Console.println(cell)
+}
+}
-- 
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