Added a system property which disables stack tr...

Added a system property which disables stack trace suppression. (At
present it is the very terse -Dscala.control.no-trace-suppression.)
This makes zero-output crashes involving things like MissingType
significantly less maddening. It would behoove us to have a central
naming scheme for such properties. Review by community.

1 files changed, 12 insertions, 4 deletions

diff --git a/src/library/scala/util/control/NoStackTrace.scala b/src/library/scala/util/control/NoStackTrace.scala
index a1cb8e0236..d8cd36aa02 100644
--- a/src/library/scala/util/control/NoStackTrace.scala
+++ b/src/library/scala/util/control/NoStackTrace.scala
@@ -9,12 +9,20 @@
 package scala.util.control
 
 /** A trait for exceptions which, for efficiency reasons, do not
- *  fill in the stack trace.
+ *  fill in the stack trace.  Stack trace suppression can be disabled
+ *  on a global basis by setting the system property named at
+ *  NoStackTrace.DisableProperty.
  *
  *  @author   Paul Phillips
  *  @since    2.8
  */
-trait NoStackTrace extends Throwable
-{
-  override def fillInStackTrace(): Throwable = this
+trait NoStackTrace extends Throwable {
+  override def fillInStackTrace(): Throwable =
+    if (sys.props contains NoStackTrace.DisableProperty) super.fillInStackTrace()
+    else this
+}
+
+object NoStackTrace {
+  // TODO: systematic naming scheme.
+  final val DisableProperty = "scala.control.no-trace-suppression"
 }