Adding some Sets/Maps to perRunCaches, and elim...

Adding some Sets/Maps to perRunCaches, and eliminating ambiguously named
imports.

Did a tour of the compiler adding a few longer-lived mutable structures
to the per-run cache clearing mechanism. Some of these were not a big
threat, but there is (almost) literally no cost to tracking them and the
fewer mutable structures which are created "lone wolf style" the easier
it is to spot the one playing by his own rules.

While I was at it I followed through on long held ambition to eliminate
the importing of highly ambiguous names like "Map" and "HashSet" from
the mutable and immutable packages. I didn't quite manage elimination
but it's pretty close. Something potentially as pernicious which I
didn't do much about is this import:

  import scala.collection._

Imagine coming across that one on lines 407 and 474 of a 1271 file.
That's not cool. Some poor future programmer will be on line 1100 and
use "Map[A, B]" in some function and only after the product has shipped
will it be discovered that the signature is wrong and the rocket will
now be crashing into the mountainside straightaway. No review.

1 files changed, 6 insertions, 7 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 1ea41ff928..713c5f607a 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -6,9 +6,8 @@
 package scala.tools.nsc
 package typechecker
 
-import scala.collection.mutable.{HashMap, WeakHashMap}
+import scala.collection.mutable
 import scala.ref.WeakReference
-import symtab.Flags
 import symtab.Flags._
 import scala.tools.nsc.io.AbstractFile
 
@@ -52,7 +51,7 @@ trait Namers { self: Analyzer =>
   // is stored in this map. The map is cleared lazily, i.e. when the new symbol
   // is created with the same name, the old one (if present) is wiped out, or the
   // entry is deleted when it is used and no longer needed.
-  private val caseClassOfModuleClass = new WeakHashMap[Symbol, WeakReference[ClassDef]]
+  private val caseClassOfModuleClass = perRunCaches.newWeakMap[Symbol, WeakReference[ClassDef]]()
 
   // Default getters of constructors are added to the companion object in the
   // typeCompleter of the constructor (methodSig). To compute the signature,
@@ -60,7 +59,7 @@ trait Namers { self: Analyzer =>
   // object, we need the templateNamer of that module class.
   // This map is extended during naming of classes, the Namer is added in when
   // it's available, i.e. in the type completer (templateSig) of the module class.
-  private[typechecker] val classAndNamerOfModule = new HashMap[Symbol, (ClassDef, Namer)]
+  private[typechecker] val classAndNamerOfModule = perRunCaches.newMap[Symbol, (ClassDef, Namer)]()
 
   def resetNamer() {
     classAndNamerOfModule.clear
@@ -548,7 +547,7 @@ trait Namers { self: Analyzer =>
 // --- Lazy Type Assignment --------------------------------------------------
 
     def typeCompleter(tree: Tree) = mkTypeCompleter(tree) { sym =>
-      if (settings.debug.value) log("defining " + sym + Flags.flagsToString(sym.flags)+sym.locationString)
+      if (settings.debug.value) log("defining " + sym + flagsToString(sym.flags)+sym.locationString)
       val tp = typeSig(tree)
       tp match {
         case TypeBounds(lo, hi) =>
@@ -1323,10 +1322,10 @@ trait Namers { self: Analyzer =>
         if (sym.hasFlag(flag1) && sym.hasFlag(flag2))
           context.error(sym.pos,
             if (flag1 == DEFERRED)
-              "abstract member may not have " + Flags.flagsToString(flag2) + " modifier";
+              "abstract member may not have " + flagsToString(flag2) + " modifier";
             else
               "illegal combination of modifiers: " +
-              Flags.flagsToString(flag1) + " and " + Flags.flagsToString(flag2) +
+              flagsToString(flag1) + " and " + flagsToString(flag2) +
               " for: " + sym);
       }