New scheme for incremental invalidation of parents.

1 files changed, 16 insertions, 8 deletions

diff --git a/src/dotty/tools/dotc/core/Denotations.scala b/src/dotty/tools/dotc/core/Denotations.scala
index 0d35f3cf9..6cbcd982f 100644
--- a/src/dotty/tools/dotc/core/Denotations.scala
+++ b/src/dotty/tools/dotc/core/Denotations.scala
@@ -17,8 +17,6 @@ import config.Config
 import util.common._
 import Decorators.SymbolIteratorDecorator
 
-
-
 /** Denotations represent the meaning of symbols and named types.
  *  The following diagram shows how the principal types of denotations
  *  and their denoting entities relate to each other. Lines ending in
@@ -463,12 +461,13 @@ object Denotations {
 
     protected def bringForward()(implicit ctx: Context): SingleDenotation = this match {
       case denot: SymDenotation if ctx.stillValid(denot) =>
+        if (denot.exists) assert(ctx.runId > validFor.runId)
         var d: SingleDenotation = denot
         do {
           d.validFor = Period(ctx.period.runId, d.validFor.firstPhaseId, d.validFor.lastPhaseId)
           d = d.nextInRun
         } while (d ne denot)
-        initial.copyIfParentInvalid
+        initial.syncWithParents
       case _ =>
         staleSymbolError
     }
@@ -506,7 +505,7 @@ object Denotations {
             var startPid = cur.validFor.lastPhaseId + 1
             val transformers = ctx.transformersFor(cur)
             val transformer = transformers.nextTransformer(startPid)
-            next = transformer.transform(cur).copyIfParentInvalid
+            next = transformer.transform(cur).syncWithParents
             if (next eq cur)
               startPid = cur.validFor.firstPhaseId
             else {
@@ -530,14 +529,20 @@ object Denotations {
       }
     }
 
-    def staleSymbolError(implicit ctx: Context) =
-      throw new StaleSymbol(s"stale symbol; $this in ${this.asSymDenotation.owner}, defined in run ${myValidFor.runId}, is referred to in run ${ctx.period.runId}")
+    def staleSymbolError(implicit ctx: Context) = {
+      def ownerMsg = this match {
+        case denot: SymDenotation => s"in ${denot.owner}"
+        case _ => ""
+      }
+      def msg = s"stale symbol; $this#${symbol.id}$ownerMsg, defined in run ${myValidFor.runId}, is referred to in run ${ctx.period.runId}"
+      throw new StaleSymbol(msg)
+    }
 
     /** For ClassDenotations only:
      *  If caches influenced by parent classes are still valid, the denotation
      *  itself, otherwise a freshly initialized copy.
      */
-    def copyIfParentInvalid(implicit ctx: Context): SingleDenotation = this
+    def syncWithParents(implicit ctx: Context): SingleDenotation = this
 
     override def toString =
       if (symbol == NoSymbol) symbol.toString
@@ -759,6 +764,9 @@ object Denotations {
         NoSymbol
   }
 
-  class StaleSymbol(msg: String) extends Exception(msg)
+  /** An exception for accessing symbols that are no longer valid in current run */
+  class StaleSymbol(msg: => String) extends Exception {
+    override def getMessage() = msg
+  }
 }