Make compiler.properties fall back to prefixed

Previously, if we wanted to override the shell.prompt property, we had
to modify compiler.properties in the jar. This change lets us do the
following, instead:

    scala -Dscala.shell.prompt="$(echo -e "\npuffnfresh> ")"

All properties previously loaded from compiler.properties now fall back
to "scala." in the system properties when not found.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/library/scala/util/Properties.scala b/src/library/scala/util/Properties.scala
index 8835730d95..367488f116 100644
--- a/src/library/scala/util/Properties.scala
+++ b/src/library/scala/util/Properties.scala
@@ -62,10 +62,10 @@ private[scala] trait PropertiesTrait {
 
   def envOrSome(name: String, alt: Option[String])       = envOrNone(name) orElse alt
 
-  // for values based on propFilename
-  def scalaPropOrElse(name: String, alt: String): String = scalaProps.getProperty(name, alt)
+  // for values based on propFilename, falling back to System properties
+  def scalaPropOrElse(name: String, alt: String): String = scalaPropOrNone(name).getOrElse(alt)
   def scalaPropOrEmpty(name: String): String             = scalaPropOrElse(name, "")
-  def scalaPropOrNone(name: String): Option[String]      = Option(scalaProps.getProperty(name))
+  def scalaPropOrNone(name: String): Option[String]      = Option(scalaProps.getProperty(name)).orElse(propOrNone("scala." + name))
 
   /** The numeric portion of the runtime Scala version, if this is a final
    *  release.  If for instance the versionString says "version 2.9.0.final",