Absolutized paths involving the scala package.

Confusing, now-it-happens now-it-doesn't mysteries lurk
in the darkness. When scala packages are declared like this:

  package scala.collection.mutable

Then paths relative to scala can easily be broken via the unlucky
presence of an empty (or nonempty) directory. Example:

  // a.scala
  package scala.foo
  class Bar { new util.Random }

  % scalac ./a.scala
  % mkdir util
  % scalac ./a.scala
  ./a.scala:4: error: type Random is not a member of package util
    new util.Random
             ^
  one error found

There are two ways to play defense against this:

 - don't use relative paths; okay sometimes, less so others
 - don't "opt out" of the scala package

This commit mostly pursues the latter, with occasional doses
of the former.

I created a scratch directory containing these empty directories:

  actors annotation ant api asm beans cmd collection compat
  concurrent control convert docutil dtd duration event factory
  forkjoin generic hashing immutable impl include internal io
  logging macros man1 matching math meta model mutable nsc parallel
  parsing partest persistent process pull ref reflect reify remote
  runtime scalap scheduler script swing sys text threadpool tools
  transform unchecked util xml

I stopped when I could compile the main src directories
even with all those empties on my classpath.

1 files changed, 26 insertions, 25 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaVersion.scala b/src/compiler/scala/tools/nsc/settings/ScalaVersion.scala
index d6a0149411..da1cc0c4cf 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaVersion.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaVersion.scala
@@ -4,7 +4,8 @@
  */
 // $Id$
 
-package scala.tools.nsc.settings
+package scala
+package tools.nsc.settings
 
 /**
  * Represents a single Scala version in a manner that
@@ -19,7 +20,7 @@ abstract class ScalaVersion extends Ordered[ScalaVersion] {
  */
 case object NoScalaVersion extends ScalaVersion {
   def unparse = "none"
-      
+
   def compare(that: ScalaVersion): Int = that match {
     case NoScalaVersion => 0
     case _ => 1
@@ -33,7 +34,7 @@ case object NoScalaVersion extends ScalaVersion {
  * to segregate builds
  */
 case class SpecificScalaVersion(major: Int, minor: Int, rev: Int, build: ScalaBuild) extends ScalaVersion {
-  def unparse = s"${major}.${minor}.${rev}.${build.unparse}"  
+  def unparse = s"${major}.${minor}.${rev}.${build.unparse}"
 
   def compare(that: ScalaVersion): Int =  that match {
     case SpecificScalaVersion(thatMajor, thatMinor, thatRev, thatBuild) =>
@@ -48,7 +49,7 @@ case class SpecificScalaVersion(major: Int, minor: Int, rev: Int, build: ScalaBu
       else build compare thatBuild
     case AnyScalaVersion => 1
     case NoScalaVersion => -1
-  }  
+  }
 }
 
 /**
@@ -56,7 +57,7 @@ case class SpecificScalaVersion(major: Int, minor: Int, rev: Int, build: ScalaBu
  */
 case object AnyScalaVersion extends ScalaVersion {
   def unparse = "any"
-      
+
   def compare(that: ScalaVersion): Int = that match {
     case AnyScalaVersion => 0
     case _ => -1
@@ -70,7 +71,7 @@ object ScalaVersion {
   private val dot = "\\."
   private val dash = "\\-"
   private def not(s:String) = s"[^${s}]"
-  private val R = s"((${not(dot)}*)(${dot}(${not(dot)}*)(${dot}(${not(dash)}*)(${dash}(.*))?)?)?)".r  
+  private val R = s"((${not(dot)}*)(${dot}(${not(dot)}*)(${dot}(${not(dash)}*)(${dash}(.*))?)?)?)".r
 
   def apply(versionString : String, errorHandler: String => Unit): ScalaVersion = {
     def errorAndValue() = {
@@ -82,41 +83,41 @@ object ScalaVersion {
         )
         AnyScalaVersion
     }
-    
+
     def toInt(s: String) = s match {
       case null | "" => 0
       case _ => s.toInt
     }
-    
+
     def isInt(s: String) = util.Try(toInt(s)).isSuccess
-    
+
     def toBuild(s: String) = s match {
       case null | "FINAL" => Final
       case s if (s.toUpperCase.startsWith("RC") && isInt(s.substring(2))) => RC(toInt(s.substring(2)))
       case s if (s.toUpperCase.startsWith("M") && isInt(s.substring(1))) => Milestone(toInt(s.substring(1)))
       case _ => Development(s)
     }
-    
+
     try versionString match {
       case "none" => NoScalaVersion
       case "any" => AnyScalaVersion
-      case R(_, majorS, _, minorS, _, revS, _, buildS) => 
+      case R(_, majorS, _, minorS, _, revS, _, buildS) =>
         SpecificScalaVersion(toInt(majorS), toInt(minorS), toInt(revS), toBuild(buildS))
-      case _ => 
+      case _ =>
         errorAndValue()
     } catch {
       case e: NumberFormatException => errorAndValue()
     }
   }
-  
-  def apply(versionString: String): ScalaVersion = 
+
+  def apply(versionString: String): ScalaVersion =
       apply(versionString, msg => throw new NumberFormatException(msg))
-  
+
   /**
    * The version of the compiler running now
    */
   val current = apply(util.Properties.versionNumberString)
-  
+
   /**
    * The 2.8.0 version.
    */
@@ -126,7 +127,7 @@ object ScalaVersion {
 /**
  * Represents the data after the dash in major.minor.rev-build
  */
-abstract class ScalaBuild extends Ordered[ScalaBuild] {  
+abstract class ScalaBuild extends Ordered[ScalaBuild] {
   /**
    * Return a version of this build information that can be parsed back into the
    * same ScalaBuild
@@ -138,7 +139,7 @@ abstract class ScalaBuild extends Ordered[ScalaBuild] {
  */
 case class Development(id: String) extends ScalaBuild {
   def unparse = s"-${id}"
-      
+
   def compare(that: ScalaBuild) = that match {
     // sorting two development builds based on id is reasonably valid for two versions created with the same schema
     // otherwise it's not correct, but since it's impossible to put a total ordering on development build versions
@@ -154,7 +155,7 @@ case class Development(id: String) extends ScalaBuild {
  */
 case object Final extends ScalaBuild {
   def unparse = ""
-      
+
   def compare(that: ScalaBuild) = that match {
     case Final => 0
     // a final is newer than anything other than a development build or another final
@@ -168,14 +169,14 @@ case object Final extends ScalaBuild {
  */
 case class RC(n: Int) extends ScalaBuild {
   def unparse = s"-RC${n}"
-      
+
   def compare(that: ScalaBuild) = that match {
     // compare two rcs based on their RC numbers
     case RC(thatN) => n - thatN
     // an rc is older than anything other than a milestone or another rc
     case Milestone(_) => 1
-    case _ => -1    
-  }  
+    case _ => -1
+  }
 }
 
 /**
@@ -183,12 +184,12 @@ case class RC(n: Int) extends ScalaBuild {
  */
 case class Milestone(n: Int) extends ScalaBuild {
   def unparse = s"-M${n}"
-      
+
   def compare(that: ScalaBuild) = that match {
     // compare two milestones based on their milestone numbers
     case Milestone(thatN) => n - thatN
     // a milestone is older than anything other than another milestone
     case _ => -1
-    
-  }  
+
+  }
 }