Tweak to symbol tracer.

Stop recording symbols once the shutdown hook is triggered
so that the symbols created in the act of dumping the symbols
do not pollute the view of what symbols were created naturally.

1 files changed, 17 insertions, 12 deletions

diff --git a/src/reflect/scala/reflect/internal/util/TraceSymbolActivity.scala b/src/reflect/scala/reflect/internal/util/TraceSymbolActivity.scala
index 5fbeb5f576..cecf8e4658 100644
--- a/src/reflect/scala/reflect/internal/util/TraceSymbolActivity.scala
+++ b/src/reflect/scala/reflect/internal/util/TraceSymbolActivity.scala
@@ -8,7 +8,8 @@ trait TraceSymbolActivity {
   val global: SymbolTable
   import global._
 
-  if (traceSymbolActivity && global.isCompilerUniverse)
+  private[this] var enabled = traceSymbolActivity
+  if (enabled && global.isCompilerUniverse)
     scala.sys addShutdownHook showAllSymbols()
 
   private type Set[T] = scala.collection.immutable.Set[T]
@@ -21,23 +22,26 @@ trait TraceSymbolActivity {
   val allTrees    = mutable.Set[Tree]()
 
   def recordSymbolsInTree(tree: Tree) {
-    allTrees += tree
+    if (enabled)
+      allTrees += tree
   }
 
   def recordNewSymbol(sym: Symbol) {
-    if (sym.id > 1) {
+    if (enabled && sym.id > 1) {
       allSymbols(sym.id) = sym
       allChildren(sym.owner.id) ::= sym.id
     }
   }
   def recordNewSymbolOwner(sym: Symbol, newOwner: Symbol) {
-    val sid = sym.id
-    val oid = sym.owner.id
-    val nid = newOwner.id
-
-    prevOwners(sid) ::= (oid -> phase)
-    allChildren(oid) = allChildren(oid) filterNot (_ == sid)
-    allChildren(nid) ::= sid
+    if (enabled) {
+      val sid = sym.id
+      val oid = sym.owner.id
+      val nid = newOwner.id
+
+      prevOwners(sid) ::= (oid -> phase)
+      allChildren(oid) = allChildren(oid) filterNot (_ == sid)
+      allChildren(nid) ::= sid
+    }
   }
 
   /** TODO.
@@ -86,7 +90,7 @@ trait TraceSymbolActivity {
     def prefix = ("  " * (sym.ownerChain.length - 1)) + sym.id
     try println("%s#%s %s".format(prefix, sym.accurateKindString, sym.name.decode))
     catch {
-      case x => println(prefix + " failed: " + x)
+      case x: Throwable => println(prefix + " failed: " + x)
     }
     allChildren(sym.id).sorted foreach showIdAndRemove
   }
@@ -128,7 +132,8 @@ trait TraceSymbolActivity {
   private def runBeforeErasure[T](body: => T): T = atPhase(findErasurePhase)(body)
 
   def showAllSymbols() {
-    if (!traceSymbolActivity) return
+    if (!enabled) return
+    enabled = false
     allSymbols(1) = NoSymbol
 
     println("" + allSymbols.size + " symbols created.")