Created -Yfatal-warnings, as otherwise I can't ...

Created -Yfatal-warnings, as otherwise I can't see how to make partest
fail on the presence of an unchecked warning. It'll come in handy
anyway. Now we have a real tough guy's command line for those who want
it:

% scalac -unchecked -deprecation -Yfatal-warnings `find . -name
'*.scala'`

Not for the timid.  Review by community.

3 files changed, 9 insertions, 4 deletions

diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index 4e14ec6fb1..92c72b1549 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -136,7 +136,9 @@ class Global(var settings: Settings, var reporter: Reporter) extends SymbolTable
 // ------------------ Reporting -------------------------------------
 
   def error(msg: String) = reporter.error(NoPosition, msg)
-  def warning(msg: String) = reporter.warning(NoPosition, msg)
+  def warning(msg: String) =
+    if (settings.Ywarnfatal.value) reporter.error(NoPosition, msg)
+    else reporter.warning(NoPosition, msg)
   def inform(msg: String) = reporter.info(NoPosition, msg, true)
   def inform[T](msg: String, value: T): T = { inform(msg+value); value }
 
diff --git a/src/compiler/scala/tools/nsc/Settings.scala b/src/compiler/scala/tools/nsc/Settings.scala
index 7cb411ffca..2d88b38777 100644
--- a/src/compiler/scala/tools/nsc/Settings.scala
+++ b/src/compiler/scala/tools/nsc/Settings.scala
@@ -943,6 +943,7 @@ trait ScalacSettings {
   val Yjenkins      = BooleanSetting    ("-Yjenkins-hashCodes", "Use jenkins hash algorithm for case class generated hashCodes.")
 
   // Warnings
+  val Ywarnfatal    = BooleanSetting    ("-Yfatal-warnings", "Fail the compilation if there are any warnings.")
   val Xwarninit     = BooleanSetting    ("-Xwarninit", "Warn about possible changes in initialization semantics")
   val Xchecknull    = BooleanSetting    ("-Xcheck-null", "Emit warning on selection of nullable reference")
   val Xwarndeadcode = BooleanSetting    ("-Ywarn-dead-code", "Emit warnings for dead code")
diff --git a/src/compiler/scala/tools/nsc/reporters/AbstractReporter.scala b/src/compiler/scala/tools/nsc/reporters/AbstractReporter.scala
index a2f6b1f247..76daa0d2fe 100644
--- a/src/compiler/scala/tools/nsc/reporters/AbstractReporter.scala
+++ b/src/compiler/scala/tools/nsc/reporters/AbstractReporter.scala
@@ -27,15 +27,17 @@ abstract class AbstractReporter extends Reporter {
   def display(pos: Position, msg: String, severity: Severity): Unit
   def displayPrompt: Unit
 
-  protected def info0(pos: Position, msg: String, severity: Severity, force: Boolean) {
+  protected def info0(pos: Position, msg: String, _severity: Severity, force: Boolean) {
+    val severity = if (settings.Ywarnfatal.value) ERROR else WARNING
+
     severity match {
       case INFO =>
         if (force || settings.verbose.value) display(pos, msg, severity)
       case WARNING =>
         val hidden = testAndLog(pos, severity)
         if (!settings.nowarnings.value) {
-	  if (!hidden || settings.prompt.value) display(pos, msg, severity)
-	  if (settings.prompt.value) displayPrompt
+          if (!hidden || settings.prompt.value) display(pos, msg, severity)
+          if (settings.prompt.value) displayPrompt
         }
       case ERROR =>
         val hidden = testAndLog(pos, severity)