Make superId management depend on TypeRefs instead of ClassSymbols.

Reason: Symbols may change on each run; TypeRefs do not.

Author: odersky

src/dotty/tools/dotc/core/Contexts.scala

@@ -149,11 +149,11 @@ object Contexts {
 
     def nextId = { _nextId += 1; _nextId }
 
-    /** A map from a superclass id to the class that has it */
-    private[core] var classOfId = new Array[ClassSymbol](InitialSuperIdsSize)
+    /** A map from a superclass id to the type-ref of the class that has it */
+    private[core] var classOfId = new Array[TypeRef](InitialSuperIdsSize)
 
-    /** A map from a superclass to its superclass id */
-    private[core] val superIdOfClass = new mutable.HashMap[ClassSymbol, Int]
+    /** A map from a the type-ref of a superclass to its superclass id */
+    private[core] val superIdOfClass = new mutable.HashMap[TypeRef, Int]
 
     /** The last allocate superclass id */
     private[core] var lastSuperId = -1
@@ -162,7 +162,7 @@ object Contexts {
     private[core] def nextSuperId: Int = {
       lastSuperId += 1;
       if (lastSuperId >= classOfId.length) {
-        val tmp = new Array[ClassSymbol](classOfId.length * 2)
+        val tmp = new Array[TypeRef](classOfId.length * 2)
         classOfId.copyToArray(tmp)
         classOfId = tmp
       }

src/dotty/tools/dotc/core/Symbols.scala

@@ -185,15 +185,16 @@ object Symbols {
 
     def superId(implicit ctx: Context): Int = {
       val hint = superIdHint
-      if (hint >= 0 && hint <= ctx.lastSuperId && (ctx.classOfId(hint) eq this)) hint
+      val key = this.typeConstructor
+      if (hint >= 0 && hint <= ctx.lastSuperId && (ctx.classOfId(hint) eq key)) hint
       else {
-        val id = ctx.superIdOfClass get this match {
+        val id = ctx.superIdOfClass get key match {
           case Some(id) =>
             id
           case None =>
             val id = ctx.nextSuperId
-            ctx.superIdOfClass(this) = id
-            ctx.classOfId(id) = this
+            ctx.superIdOfClass(key) = id
+            ctx.classOfId(id) = key
             id
         }
         superIdHint = id