Fixed an ambiguity problem with implcits, and a...

Fixed an ambiguity problem with implcits, and a spurious cyclic
reference error mentioned by Jorge. Tightened overriding checks (test
case is new collection libraries).

4 files changed, 39 insertions, 12 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/OverridingPairs.scala b/src/compiler/scala/tools/nsc/transform/OverridingPairs.scala
index 9266515057..8f8d6a5bea 100644
--- a/src/compiler/scala/tools/nsc/transform/OverridingPairs.scala
+++ b/src/compiler/scala/tools/nsc/transform/OverridingPairs.scala
@@ -117,6 +117,7 @@ abstract class OverridingPairs {
      *     i = index(p)
      *     j = index(b)
      *     p isSubClass b
+     *     p.baseType(b) == self.baseType(b)
      */
     private val subParents = new Array[BitSet](size)
 
@@ -124,7 +125,11 @@ abstract class OverridingPairs {
         subParents(i) = new BitSet(size);
       for (p <- parents) {
         val pIndex = index(p.typeSymbol)
-        for (bc <- p.baseClasses) include(subParents(index(bc)), pIndex)
+        for (bc <- p.baseClasses)
+          if (p.baseType(bc) =:= self.baseType(bc))
+            include(subParents(index(bc)), pIndex)
+          else if (settings.debug.value)
+            log("SKIPPING "+p+" -> "+p.baseType(bc)+" / "+self.baseType(bc)+" from "+base)
       }
     }
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 18f221fab9..213bbf173a 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -630,6 +630,18 @@ trait Contexts { self: Analyzer =>
       if (tpeCache eq null) tpeCache = pre.memberType(sym)
       tpeCache
     }
+    override def equals(other: Any) = other match {
+      case that: ImplicitInfo =>
+        if (this eq NoImplicitInfo) that eq this
+        else
+          this.name == that.name &&
+          this.pre =:= that.pre &&
+          this.sym == that.sym
+      case _ =>
+        false
+    }
+    override def hashCode =
+      name.hashCode + pre.hashCode + sym.hashCode
     override def toString = "ImplicitInfo(" + name + "," + pre + "," + sym + ")"
   }
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index f3fe615e80..6e648371ea 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -27,17 +27,20 @@ trait Namers { self: Analyzer =>
    *  2. The skolem is a method parameter which appears in parameter `tparams'
    */
   class DeSkolemizeMap(tparams: List[Symbol]) extends TypeMap {
-    def apply(tp: Type): Type = tp match {
-      case TypeRef(pre, sym, args)
-      if (sym.isTypeSkolem && (tparams contains sym.deSkolemize)) =>
-        mapOver(rawTypeRef(NoPrefix, sym.deSkolemize, args))
-      case PolyType(tparams1, restpe) =>
-        new DeSkolemizeMap(tparams1 ::: tparams).mapOver(tp)
-      case ClassInfoType(parents, decls, clazz) =>
-        val parents1 = List.mapConserve(parents)(this)
+    def apply(tp: Type): Type = if (tparams.isEmpty) tp
+    else {
+      tp match {
+        case TypeRef(pre, sym, args)
+        if (sym.isTypeSkolem && (tparams contains sym.deSkolemize)) =>
+          mapOver(rawTypeRef(NoPrefix, sym.deSkolemize, args))
+        case PolyType(tparams1, restpe) =>
+          new DeSkolemizeMap(tparams1 ::: tparams).mapOver(tp)
+        case ClassInfoType(parents, decls, clazz) =>
+          val parents1 = List.mapConserve(parents)(this)
         if (parents1 eq parents) tp else ClassInfoType(parents1, decls, clazz)
-      case _ =>
-        mapOver(tp)
+        case _ =>
+          mapOver(tp)
+      }
     }
   }
   private class NormalNamer(context : Context) extends Namer(context)
@@ -415,7 +418,7 @@ trait Namers { self: Analyzer =>
 // --- Lazy Type Assignment --------------------------------------------------
 
     def typeCompleter(tree: Tree) = mkTypeCompleter(tree) { sym =>
-      if (settings.debug.value) log("defining " + sym + Flags.flagsToString(sym.flags));
+      if (settings.debug.value) log("defining " + sym + Flags.flagsToString(sym.flags)+sym.locationString)
       val tp = typeSig(tree)
       tp match {
         case TypeBounds(lo, hi) =>
diff --git a/test/files/pos/cyclics.scala b/test/files/pos/cyclics.scala
new file mode 100644
index 0000000000..69092ce7ab
--- /dev/null
+++ b/test/files/pos/cyclics.scala
@@ -0,0 +1,7 @@
+trait Param[T]
+trait Abs { type T }
+trait Cyclic1[A <: Param[A]]    // works
+trait Cyclic2[A <: Abs { type T <: A }]    // fails
+trait Cyclic3 { type A <: Abs { type T = A } }    // fails
+trait Cyclic4 { type A <: Param[A] }   // works
+