Existential printing, plus more compiler testing infrastructure.

Direct compiler internals testing. It's really easy, you should probably
use it about 1000 times each. Look at the test:

  run/existentials-in-compiler.scala

The checkfile contains the (string representations of the) actual
existentials from the compiler to make sure they correspond properly to
the ones in the source.

Existentials were being printed with wildcards too freely; this has been
tightened up.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index 18735cafe2..4493188b31 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -807,6 +807,10 @@ class Global(var currentSettings: Settings, var reporter: Reporter) extends Symb
   def currentRun: Run              = curRun
   def currentUnit: CompilationUnit = if (currentRun eq null) NoCompilationUnit else currentRun.currentUnit
   def currentSource: SourceFile    = if (currentUnit.exists) currentUnit.source else lastSeenSourceFile
+  
+  @inline final def afterTyper[T](op: => T): T = afterPhase(currentRun.typerPhase)(op)
+  @inline final def beforeErasure[T](op: => T): T = beforePhase(currentRun.erasurePhase)(op)
+  @inline final def afterErasure[T](op: => T): T = afterPhase(currentRun.erasurePhase)(op)
 
   /** Don't want to introduce new errors trying to report errors,
    *  so swallow exceptions.
@@ -1114,7 +1118,7 @@ class Global(var currentSettings: Settings, var reporter: Reporter) extends Symb
       lazy val trackers = currentRun.units.toList map (x => SymbolTracker(x))
       def snapshot() = {
         inform("\n[[symbol layout at end of " + phase + "]]")
-        atPhase(phase.next) {
+        afterPhase(phase) {
           trackers foreach { t =>
             t.snapshot()
             inform(t.show("Heading from " + phase.prev.name + " to " + phase.name))
@@ -1389,7 +1393,7 @@ class Global(var currentSettings: Settings, var reporter: Reporter) extends Symb
 
   def printAllUnits() {
     print("[[syntax trees at end of " + phase + "]]")
-    atPhase(phase.next) { currentRun.units foreach (treePrinter.print(_)) }
+    afterPhase(phase) { currentRun.units foreach (treePrinter.print(_)) }
   }
 
   private def findMemberFromRoot(fullName: Name): Symbol = {