From 148736c3df1fa6463b4b2658c01bcf452a52c224 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Fri, 7 Jan 2011 14:44:18 +0000
Subject: Made NamesDefault more robust to support idempo...

Made NamesDefault more robust to support idempotent compilation.
---
 src/compiler/scala/tools/nsc/typechecker/Namers.scala      |  7 +++++++
 .../scala/tools/nsc/typechecker/NamesDefaults.scala        |  8 ++++++--
 src/compiler/scala/tools/nsc/typechecker/Typers.scala      | 14 ++++++++++----
 3 files changed, 23 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 5aabe7a72e..4bebc0fddc 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -1036,6 +1036,13 @@ trait Namers { self: Analyzer =>
             if (!isConstr)
               meth.owner.resetFlag(INTERFACE) // there's a concrete member now
             val default = parentNamer.enterSyntheticSym(defaultTree)
+            if (forInteractive && default.owner.isTerm) {
+              // enter into map from method symbols to default arguments.
+              // if compiling the same local block several times (which can happen in interactive mode)
+              // we might otherwise not find the default symbol, because the second time it the
+              // method symbol will be re-entered in the scope but the default parameter will not.
+              defaultParametersOfMethod(meth) += default
+            }
           } else if (baseHasDefault) {
             // the parameter does not have a default itself, but the corresponding parameter
             // in the base class does.
diff --git a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
index 7982617fee..0c9bebd510 100644
--- a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
@@ -8,7 +8,8 @@ package typechecker
 
 import symtab.Flags._
 
-import scala.collection.mutable.ListBuffer
+import scala.collection.mutable.{ListBuffer, WeakHashMap}
+import scala.collection.immutable.Set
 
 /**
  *  @author Lukas Rytz
@@ -19,6 +20,10 @@ trait NamesDefaults { self: Analyzer =>
   import global._
   import definitions._
 
+  val defaultParametersOfMethod = new WeakHashMap[Symbol, Set[Symbol]] {
+    override def default(key: Symbol) = Set()
+  }
+
   case class NamedApplyInfo(qual: Option[Tree], targs: List[Tree],
                             vargss: List[List[Tree]], blockTyper: Typer)
   val noApplyInfo = NamedApplyInfo(None, Nil, Nil, null)
@@ -29,7 +34,6 @@ trait NamesDefaults { self: Analyzer =>
   }
   def isNamed(arg: Tree) = nameOf(arg).isDefined
 
-
   /** @param pos maps indicies from old to new */
   def reorderArgs[T: ClassManifest](args: List[T], pos: Int => Int): List[T] = {
     val res = new Array[T](args.length)
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 7ef219bb23..2099278fe3 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1797,14 +1797,20 @@ trait Typers extends Modes {
      */
     def typedBlock(block: Block, mode: Int, pt: Type): Block = {
       val syntheticPrivates = new ListBuffer[Symbol]
+      def enterIfNotThere(sym: Symbol) {
+        var e = context.scope.lookupEntry(sym.name)
+        while ((e ne null) && (e.sym ne sym)) e = e.tail
+        if (e eq null) context.scope.enter(sym)
+      }
       try {
         namer.enterSyms(block.stats)
         for (stat <- block.stats) {
           if (forInteractive && stat.isDef) {
-            // this might be redundant now
-            var e = context.scope.lookupEntry(stat.symbol.name)
-            while ((e ne null) && (e.sym ne stat.symbol)) e = e.tail
-            if (e eq null) context.scope.enter(stat.symbol)
+            // this logic is needed in case typer was interrupted half way through a block and then comes
+            // back to do the block again. In that case the definitions that were already attributed as well as any
+            // default parameters of such methods need to be re-entered in the current scope.
+            enterIfNotThere(stat.symbol)
+            defaultParametersOfMethod(stat.symbol) foreach enterIfNotThere
           }
           enterLabelDef(stat)
         }
-- 
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