From f9a68fb01de1edd3fa620912bbe75897133cc81b Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Fri, 4 Apr 2008 18:00:26 +0000
Subject: (1) more changes for dynamic cycle detection of...

(1) more changes for dynamic cycle detection of implicits 2) change
(to wildcard scoping in types 3) suppress $tag generation for purely
(abstract traits 4) increase stacksize for sabbus to 32m (otherwise
(problems on Windows)
---
 sabbus.xml                                         |  2 +-
 .../scala/tools/nsc/ast/parser/Parsers.scala       | 68 ++++++++++++----------
 .../scala/tools/nsc/typechecker/Contexts.scala     | 28 +++++----
 .../tools/nsc/typechecker/SyntheticMethods.scala   |  2 +-
 .../scala/tools/nsc/typechecker/Typers.scala       | 47 +++++++++------
 src/library/jvm/scala/Predef.scala                 |  2 +-
 test/files/neg/bug696.check                        |  3 +-
 test/files/neg/divergent-implicit.check            | 17 ++++++
 test/files/neg/divergent-implicit.scala            | 16 +++++
 test/files/run/existentials.scala                  |  2 +-
 10 files changed, 122 insertions(+), 65 deletions(-)
 create mode 100644 test/files/neg/divergent-implicit.check
 create mode 100644 test/files/neg/divergent-implicit.scala

diff --git a/sabbus.xml b/sabbus.xml
index ae4a142189..b2d7ec2b2a 100644
--- a/sabbus.xml
+++ b/sabbus.xml
@@ -92,7 +92,7 @@ PROPERTIES
   
   <property name="copyright.string" value="Copyright 2002-2008, LAMP/EPFL"/>
   
-  <property name="java.flags" value="-Xmx256M -Xms16M"/>
+  <property name="java.flags" value="-Xmx256M -Xms32M"/>
 
 <!-- ===========================================================================
 INITIALISATION
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index 04334951ec..fd1db30e74 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -191,8 +191,11 @@ trait Parsers extends NewScanners with MarkupParsers {
       val savedPlaceholderTypes = placeholderTypes
       placeholderTypes = List()
       var t = op
-      if (!placeholderTypes.isEmpty) t = ExistentialTypeTree(t, placeholderTypes.reverse)
-      placeholderTypes = savedPlaceholderTypes
+      if (!placeholderTypes.isEmpty && t.isInstanceOf[AppliedTypeTree]) {
+        t = ExistentialTypeTree(t, placeholderTypes.reverse)
+        placeholderTypes = List()
+      }
+      placeholderTypes = placeholderTypes ::: savedPlaceholderTypes
       t
     }
 
@@ -646,7 +649,7 @@ trait Parsers extends NewScanners with MarkupParsers {
     /** TypedOpt ::= [`:' Type]
     */
     def typedOpt(): Tree =
-      if (inToken == COLON) { inNextToken; placeholderTypeBoundary(typ()) }
+      if (inToken == COLON) { inNextToken; typ() }
       else TypeTree()
 
     /** RequiresTypedOpt ::= [requires AnnotType]
@@ -654,7 +657,7 @@ trait Parsers extends NewScanners with MarkupParsers {
     def requiresTypeOpt(): Tree =
       if (inToken == REQUIRES) {
         deprecationWarning(in.currentPos, "`requires T' has been deprecated; use `{ self: T => ...'  instead")
-        inNextToken; placeholderTypeBoundary(annotType(false))
+        inNextToken; annotType(false)
       } else TypeTree()
 
     /** Types ::= Type {`,' Type}
@@ -686,24 +689,26 @@ trait Parsers extends NewScanners with MarkupParsers {
      *  ExistentialClause ::= forSome `{' ExistentialDcl {semi ExistentialDcl}} `}'
      *  ExistentialDcl    ::= type TypeDcl | val ValDcl
      */
-    def typ(): Tree = {
+    def typ(): Tree = typ(false)
+
+    def typ(isPattern: Boolean): Tree = placeholderTypeBoundary {
       val t =
         if (inToken == LPAREN) {
           val pos = inSkipToken
           if (inToken == RPAREN) {
             inNextToken
-            atPos(accept(ARROW)) { makeFunctionTypeTree(List(), typ()) }
+            atPos(accept(ARROW)) { makeFunctionTypeTree(List(), typ(isPattern)) }
           /* Not more used
           } else if (inToken == ARROW) {
             inNextToken
-            val t0 = typ()
+            val t0 = typ(isPattern)
             accept(RPAREN)
-            atPos(accept(ARROW)) { makeByNameFunctionTypeTree(t0, typ()) }
+            atPos(accept(ARROW)) { makeByNameFunctionTypeTree(t0, typ(isPattern)) }
           */
           } else {
-            val ts = types(false, false, true)
+            val ts = types(isPattern, false, true)
             accept(RPAREN)
-            if (inToken == ARROW) atPos(inSkipToken) { makeFunctionTypeTree(ts, typ()) }
+            if (inToken == ARROW) atPos(inSkipToken) { makeFunctionTypeTree(ts, typ(isPattern)) }
             else {
               for (t <- ts) t match {
                 case AppliedTypeTree(Select(_, n), _)
@@ -711,15 +716,15 @@ trait Parsers extends NewScanners with MarkupParsers {
                   syntaxError(t.pos, "no by-name parameter type allowed here", false)
                 case _ =>
               }
-              infixTypeRest(pos, annotTypeRest(pos, false, makeTupleType(ts, true)), false, InfixMode.FirstOp)
+              infixTypeRest(pos, annotTypeRest(pos, isPattern, makeTupleType(ts, true)), false, InfixMode.FirstOp)
             }
           }
         } else {
-          infixType(false, InfixMode.FirstOp)
+          infixType(isPattern, InfixMode.FirstOp)
         }
       if (inToken == ARROW)
         atPos(inSkipToken) {
-          makeFunctionTypeTree(List(t), typ())
+          makeFunctionTypeTree(List(t), typ(isPattern))
         }
       else if (inToken == FORSOME)
         atPos(inSkipToken) {
@@ -739,8 +744,9 @@ trait Parsers extends NewScanners with MarkupParsers {
 
     /** InfixType ::= CompoundType {id [nl] CompoundType}
      */
-    def infixType(isPattern: Boolean, mode: InfixMode.Value): Tree =
+    def infixType(isPattern: Boolean, mode: InfixMode.Value): Tree = placeholderTypeBoundary {
       infixTypeRest(inCurrentPos, infixTypeFirst(isPattern), isPattern, mode)
+    }
 
     def infixTypeFirst(isPattern: Boolean) =
       if (inToken == LBRACE) scalaAnyRefConstr else annotType(isPattern)
@@ -790,7 +796,7 @@ trait Parsers extends NewScanners with MarkupParsers {
      *                     |  `(' Types [`,'] `)'
      *                     |  WildcardType
      */
-    def annotType(isPattern: Boolean): Tree = {
+    def annotType(isPattern: Boolean): Tree = placeholderTypeBoundary {
       val annots1 = annotations()
       if (!annots1.isEmpty)
 	deprecationWarning(
@@ -864,7 +870,7 @@ trait Parsers extends NewScanners with MarkupParsers {
             Bind(ident().toTypeName, EmptyTree)
           }
         else {
-          typ()
+          typ(true)
         }
       } else if (isFuncArg) {
         // copy-paste (with change) from def paramType
@@ -884,7 +890,7 @@ trait Parsers extends NewScanners with MarkupParsers {
           } else t
         }
       } else if (isTypeApply) {
-        placeholderTypeBoundary(typ())
+        typ()
       } else {
         typ()
       }
@@ -1045,8 +1051,7 @@ trait Parsers extends NewScanners with MarkupParsers {
               }
             } else if (annots.isEmpty || isTypeIntro) {
               t = atPos(pos) {
-                val tpt = placeholderTypeBoundary(
-                  if (location != Local) compoundType(false) else typ())
+                val tpt = if (location != Local) compoundType(false) else typ()
                 if (isWildcard(t))
                   (placeholderParams: @unchecked) match {
                     case (vd @ ValDef(mods, name, _, _)) :: rest =>
@@ -1072,10 +1077,11 @@ trait Parsers extends NewScanners with MarkupParsers {
           }
           stripParens(t)
       }
-      if (!placeholderParams.isEmpty)
-        if (isWildcard(res)) savedPlaceholderParams = placeholderParams ::: savedPlaceholderParams
-        else res = atPos(res.pos){Function(placeholderParams.reverse, res)}
-      placeholderParams = savedPlaceholderParams
+      if (!placeholderParams.isEmpty && !isWildcard(res)) {
+        res = atPos(res.pos){ Function(placeholderParams.reverse, res) }
+        placeholderParams = List()
+      }
+      placeholderParams = placeholderParams ::: savedPlaceholderParams
       res
     }
 
@@ -1356,7 +1362,7 @@ trait Parsers extends NewScanners with MarkupParsers {
         val p = pattern2(seqOK)
         p match {
           case Ident(name) if (treeInfo.isVarPattern(p) && inToken == COLON) =>
-            atPos(inSkipToken) { Typed(p, placeholderTypeBoundary(compoundType(true))) }
+            atPos(inSkipToken) { Typed(p, compoundType(true)) }
           case _ =>
             p
         }
@@ -1746,10 +1752,10 @@ trait Parsers extends NewScanners with MarkupParsers {
       if (inToken == ARROW)
         atPos(inSkipToken) {
           AppliedTypeTree(
-              scalaDot(nme.BYNAME_PARAM_CLASS_NAME.toTypeName), List(placeholderTypeBoundary(typ())))
+              scalaDot(nme.BYNAME_PARAM_CLASS_NAME.toTypeName), List(typ()))
         }
       else {
-        val t = placeholderTypeBoundary(typ())
+        val t = typ()
         if (isIdent && inName == STAR) {
           inNextToken
           atPos(t.pos) {
@@ -1789,7 +1795,7 @@ trait Parsers extends NewScanners with MarkupParsers {
         val param = atPos(pos) { TypeDef(mods, pname, tparams, typeBounds()) }
         if (inToken == VIEWBOUND && (implicitViewBuf ne null))
           implicitViewBuf += atPos(inSkipToken) {
-            makeFunctionTypeTree(List(Ident(pname)), placeholderTypeBoundary(typ()))
+            makeFunctionTypeTree(List(Ident(pname)), typ())
           }
         param
       }
@@ -1815,7 +1821,7 @@ trait Parsers extends NewScanners with MarkupParsers {
         bound(SUBTYPE, nme.Any))
 
     def bound(tok: Int, default: Name): Tree =
-      if (inToken == tok) { inNextToken; placeholderTypeBoundary(typ()) }
+      if (inToken == tok) { inNextToken; typ() }
       else scalaDot(default.toTypeName)
 
 //////// DEFS ////////////////////////////////////////////////////////////////
@@ -2125,7 +2131,7 @@ trait Parsers extends NewScanners with MarkupParsers {
         inToken match {
           case EQUALS =>
             inNextToken
-            TypeDef(mods, name, tparams, placeholderTypeBoundary(typ()))
+            TypeDef(mods, name, tparams, typ())
           case SUPERTYPE | SUBTYPE | SEMI | NEWLINE | NEWLINES | COMMA | RBRACE =>
             TypeDef(mods | Flags.DEFERRED, name, tparams, typeBounds())
           case _ =>
@@ -2222,14 +2228,14 @@ trait Parsers extends NewScanners with MarkupParsers {
      *  TraitParents       ::= AnnotType {with AnnotType}
      */
     def templateParents(isTrait: Boolean): (List[Tree], List[List[Tree]]) = {
-      val parents = new ListBuffer[Tree] + placeholderTypeBoundary(annotType(false))
+      val parents = new ListBuffer[Tree] + annotType(false)
       val argss = new ListBuffer[List[Tree]]
       if (inToken == LPAREN && !isTrait)
         do { argss += argumentExprs() } while (inToken == LPAREN)
       else argss += List()
       while (inToken == WITH) {
         inNextToken
-        parents += placeholderTypeBoundary(annotType(false))
+        parents += annotType(false)
       }
       (parents.toList, argss.toList)
     }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 1f0750d580..758a006e0e 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -97,8 +97,9 @@ trait Contexts { self: Analyzer =>
     private var _undetparams: List[Symbol] = List() // Undetermined type parameters,
                                                     // not inherited to child contexts
     var depth: Int = 0
-    var imports: List[ImportInfo] = List()
-
+    var imports: List[ImportInfo] = List()   // currently visible imports
+    var openImplicits: List[Type] = List()   // types for which implicit arguments
+                                             // are currently searched
     var prefix: Type = NoPrefix
     var inConstructorSuffix = false         // are we in a secondary constructor
                                             // after the this constructor call?
@@ -130,6 +131,7 @@ trait Contexts { self: Analyzer =>
       txt._undetparams = _undetparams
       txt.depth = depth
       txt.imports = imports
+      txt.openImplicits = openImplicits
       txt.prefix = prefix
       txt.inConstructorSuffix = inConstructorSuffix
       txt.returnsSeen = returnsSeen
@@ -169,15 +171,16 @@ trait Contexts { self: Analyzer =>
         val a8 = eq(depth, that.depth)
         val a9 = eq(imports, that.imports)
 
-        val a10 = eq(prefix, that.prefix)
-        val a11 = eq(inConstructorSuffix, that.inConstructorSuffix)
-        val a12 = eq(implicitsEnabled, that.implicitsEnabled)
-        val a13 = eq(checking, that.checking)
-        val a14 = eq(retyping, that.retyping)
-        val a15 = eq(savedTypeBounds, that.savedTypeBounds)
-        val a16 = eq(unit, that.unit)
-        val ret = a0 && a1 && a2 && a3 && a4 && a5 && a6 && a7 && a8 && a9 && a10 && a11 && a12 && a13 && a14 && a15 && a16
-        val a17 = {
+        val a10 = eq(openImplicits, that.openImplicits)
+        val a11 = eq(prefix, that.prefix)
+        val a12 = eq(inConstructorSuffix, that.inConstructorSuffix)
+        val a13 = eq(implicitsEnabled, that.implicitsEnabled)
+        val a14 = eq(checking, that.checking)
+        val a15 = eq(retyping, that.retyping)
+        val a16 = eq(savedTypeBounds, that.savedTypeBounds)
+        val a17 = eq(unit, that.unit)
+        val ret = a0 && a1 && a2 && a3 && a4 && a5 && a6 && a7 && a8 && a9 && a10 && a11 && a12 && a13 && a14 && a15 && a16 && a17
+        val a18 = {
           if (implicitsRunId > that.implicitsRunId) {
             that.implicitsRunId = NoRunId
             that.implicitsCache = null
@@ -189,7 +192,7 @@ trait Contexts { self: Analyzer =>
           implicitsCache == that.implicitsCache
         }
         if (ret) {
-          if (!a17) {
+          if (!a18) {
             //assert(this.implicitsCache == null || that.implicitsCache == null)
           }
         }
@@ -252,6 +255,7 @@ trait Contexts { self: Analyzer =>
       c.implicitsEnabled = this.implicitsEnabled
       c.checking = this.checking
       c.retyping = this.retyping
+      c.openImplicits = this.openImplicits
       c
     }
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
index e3a4ae897d..89b4b85cb0 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
@@ -265,7 +265,7 @@ trait SyntheticMethods { self: Analyzer =>
                 stat.symbol.resetFlag(CASEACCESSOR)
               }
             }
-            if (!inIDE && clazz.info.nonPrivateDecl(nme.tag) == NoSymbol) ts += tagMethod
+            if (!inIDE && !clazz.hasFlag(INTERFACE) && clazz.info.nonPrivateDecl(nme.tag) == NoSymbol) ts += tagMethod
           }
           if (clazz.isModuleClass) {
             if (!hasOverridingImplementation(Object_toString)) ts += moduleToStringMethod
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index c34212cd8d..12e0e63960 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -134,7 +134,7 @@ trait Typers { self: Analyzer =>
   private def argMode(fun: Tree, mode: Int) =
     if (treeInfo.isSelfOrSuperConstrCall(fun)) mode | SCCmode else mode
 
-  private var pendingImplicits: List[Type] = List()
+  private val DivergentImplicit = new Exception()
 
   abstract class Typer(context0: Context) {
     import context0.unit
@@ -3297,26 +3297,28 @@ trait Typers { self: Analyzer =>
     }
 
     private def dominates(dtor: Type, dted: Type): Boolean = {
-      def simplify(tp: Type): Type = tp match {
-        case RefinedType(parents, defs) => intersectionType(parents, tp.typeSymbol.owner)
-        case AnnotatedType(attribs, tp, selfsym) => tp
+      def core(tp: Type): Type = tp.normalize match {
+        case RefinedType(parents, defs) => intersectionType(parents map core, tp.typeSymbol.owner)
+        case AnnotatedType(attribs, tp, selfsym) => core(tp)
+        case ExistentialType(tparams, result) => core(result).subst(tparams, tparams map (t => core(t.info.bounds.hi)))
+        case PolyType(tparams, result) => core(result).subst(tparams, tparams map (t => core(t.info.bounds.hi)))
         case _ => tp
       }
       def sum(xs: List[Int]) = (0 /: xs)(_ + _)
       def complexity(tp: Type): Int = tp match {
         case SingleType(pre, sym) => complexity(pre) + 1
         case TypeRef(pre, sym, args) => complexity(pre) + sum(args map complexity) + 1
-        case TypeBounds(lo, hi) =>  complexity(lo) + complexity(hi)
-        case ClassInfoType(parents, defs, clazz) => sum(parents map complexity) + 1
-        case MethodType(paramtypes, result) => sum(paramtypes map complexity) + complexity(result) + 1
-        case PolyType(tparams, result) => sum(tparams map (_.info) map complexity) + complexity(result) + 1
-        case ExistentialType(tparams, result) => sum(tparams map (_.info) map complexity) + complexity(result) + 1
+        case RefinedType(parents, _) => sum(parents map complexity) + 1
         case _ => 1
       }
-      val dtor1 = simplify(dtor)
-      val dted1 = simplify(dted)
-      (dtor1.typeSymbol == dted1.typeSymbol) &&
-      (dtor1 =:= dted1 || complexity(dtor1) > complexity(dted1))
+      def overlaps(tp1: Type, tp2: Type): Boolean = (tp1, tp2) match {
+        case (RefinedType(parents, _), _) => parents exists (overlaps(_, tp2))
+        case (_, RefinedType(parents, _)) => parents exists (overlaps(tp1, _))
+        case _ => tp1.typeSymbol == tp2.typeSymbol
+      }
+      val dtor1 = core(dtor)
+      val dted1 = core(dted)
+      overlaps(dtor1, dted1) && (dtor1 =:= dted1 || complexity(dtor1) > complexity(dted1))
     }
 
     /** Try to construct a typed tree from given implicit info with given
@@ -3332,16 +3334,27 @@ trait Typers { self: Analyzer =>
      *  @pre           <code>info.tpe</code> does not contain an error
      */
     private def typedImplicit(pos: Position, info: ImplicitInfo, pt0: Type, pt: Type, isLocal: Boolean): Tree =
-       pendingImplicits find (dominates(pt, _)) match {
+       context.openImplicits find (dominates(pt, _)) match {
          case Some(pending) =>
-           context.error(pos, "diverging implicit expansion for type "+pending)
+           throw DivergentImplicit
            EmptyTree
          case None =>
            try {
-             pendingImplicits = pt :: pendingImplicits
+             context.openImplicits = pt :: context.openImplicits
              typedImplicit0(pos, info, pt0, pt, isLocal)
+           } catch {
+             case DivergentImplicit =>
+               if (context.openImplicits.tail.isEmpty) {
+                 if (!(pt.isErroneous))
+                   context.unit.error(
+                     pos, "diverging implicit expansion for type "+pt+"\nstarting with "+
+                     info.sym+info.sym.locationString)
+                 EmptyTree
+               } else {
+                 throw DivergentImplicit
+               }
            } finally {
-             pendingImplicits = pendingImplicits.tail
+             context.openImplicits = context.openImplicits.tail
            }
        }
 
diff --git a/src/library/jvm/scala/Predef.scala b/src/library/jvm/scala/Predef.scala
index 74409b1e4b..c7a01d6642 100644
--- a/src/library/jvm/scala/Predef.scala
+++ b/src/library/jvm/scala/Predef.scala
@@ -187,7 +187,7 @@ object Predef {
   implicit def booleanWrapper(x: Boolean)  = new runtime.RichBoolean(x)
 
   implicit def stringWrapper(x: String) = new runtime.RichString(x)
-  implicit def stringBuilderWrapper(x : StringBuilder) = new runtime.RichStringBuilder(x)
+  implicit def stringBuilderWrapper(x : StringBuilder): runtime.RichStringBuilder = new runtime.RichStringBuilder(x)
 
   implicit def any2stringadd(x: Any) = new runtime.StringAdd(x)
 
diff --git a/test/files/neg/bug696.check b/test/files/neg/bug696.check
index 7d9d2687b0..623c95f62c 100644
--- a/test/files/neg/bug696.check
+++ b/test/files/neg/bug696.check
@@ -1,4 +1,5 @@
-bug696.scala:4: error: no implicit argument matching parameter type TypeUtil0.Type[Any] was found.
+bug696.scala:4: error: diverging implicit expansion for type TypeUtil0.Type[Any]
+starting with method WithType in object TypeUtil0
   as[Any](null);
   ^
 one error found
diff --git a/test/files/neg/divergent-implicit.check b/test/files/neg/divergent-implicit.check
new file mode 100644
index 0000000000..8d57f92716
--- /dev/null
+++ b/test/files/neg/divergent-implicit.check
@@ -0,0 +1,17 @@
+divergent-implicit.scala:4: error: diverging implicit expansion for type (Int) => B
+starting with method cast in object Test1
+  val x1: String = 1
+                   ^
+divergent-implicit.scala:5: error: diverging implicit expansion for type (Int) => String
+starting with method cast in object Test1
+  val x2: String = cast[Int, String](1)
+                   ^
+divergent-implicit.scala:14: error: diverging implicit expansion for type (Test2.Baz) => Test2.Bar
+starting with method baz2bar in object Test2
+  val x: Bar = new Foo
+               ^
+divergent-implicit.scala:15: error: diverging implicit expansion for type (Test2.Foo) => Test2.Bar
+starting with method foo2bar in object Test2
+  val y: Bar = new Baz
+               ^
+four errors found
diff --git a/test/files/neg/divergent-implicit.scala b/test/files/neg/divergent-implicit.scala
new file mode 100644
index 0000000000..4a356d54f7
--- /dev/null
+++ b/test/files/neg/divergent-implicit.scala
@@ -0,0 +1,16 @@
+object Test1 {
+  implicit def cast[A, B](x: A)(implicit c: A => B): B = c(x)
+
+  val x1: String = 1
+  val x2: String = cast[Int, String](1)
+}
+object Test2 {
+  class Foo
+  class Bar
+  class Baz
+  implicit def foo2bar(x: Foo)(implicit baz2bar: Baz => Bar): Bar = baz2bar(new Baz)
+  implicit def baz2bar(x: Baz)(implicit foo2bar: Foo => Bar): Bar = foo2bar(new Foo)
+
+  val x: Bar = new Foo
+  val y: Bar = new Baz
+}
diff --git a/test/files/run/existentials.scala b/test/files/run/existentials.scala
index 9dc9855a75..42711df5f2 100755
--- a/test/files/run/existentials.scala
+++ b/test/files/run/existentials.scala
@@ -62,7 +62,7 @@ object Test extends Application {
      case _ =>
    }
 
-   def fooW(x : Counter[_] { def name : String }) = x match {
+   def fooW(x : Counter[T] { def name : String } forSome { type T }) = x match {
      case ctr: Counter[t] =>
        val c = ctr.newCounter
        println(ctr.name+" "+ctr.get(ctr.inc(ctr.inc(c))))
-- 
cgit v1.2.3