1 files changed, 25 insertions, 12 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 0cdece59e1..f15bd3c31c 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -22,13 +22,9 @@ trait ScalaSettings extends AbsScalaSettings
   /** Set of settings */
   protected[scala] lazy val allSettings = mutable.HashSet[Setting]()
 
-  /** Against my better judgment, giving in to martin here and allowing
-   *  CLASSPATH to be used automatically.  So for the user-specified part
-   *  of the classpath:
-   *
-   *  - If -classpath or -cp is given, it is that
-   *  - Otherwise, if CLASSPATH is set, it is that
-   *  - If neither of those, then "." is used.
+  /** The user class path, specified by `-classpath` or `-cp`,
+   *  defaults to the value of CLASSPATH env var if it is set, as in Java,
+   *  or else to `"."` for the current user directory.
    */
   protected def defaultClasspath = sys.env.getOrElse("CLASSPATH", ".")
 
@@ -134,8 +130,9 @@ trait ScalaSettings extends AbsScalaSettings
   val Xshowobj           = StringSetting       ("-Xshow-object", "object", "Show internal representation of object.", "")
   val showPhases         = BooleanSetting      ("-Xshow-phases", "Print a synopsis of compiler phases.")
   val sourceReader       = StringSetting       ("-Xsource-reader", "classname", "Specify a custom method for reading source files.", "")
+  val reporter           = StringSetting       ("-Xreporter", "classname", "Specify a custom reporter for compiler messages.", "scala.tools.nsc.reporters.ConsoleReporter")
   val strictInference    = BooleanSetting      ("-Xstrict-inference", "Don't infer known-unsound types")
-  val source             = ScalaVersionSetting ("-Xsource", "version", "Treat compiler input as Scala source for the specified version, see SI-8126.", initial = ScalaVersion("2.11"))
+  val source             = ScalaVersionSetting ("-Xsource", "version", "Treat compiler input as Scala source for the specified version, see SI-8126.", initial = ScalaVersion("2.12"))
 
   val XnoPatmatAnalysis = BooleanSetting ("-Xno-patmat-analysis", "Don't perform exhaustivity/unreachability analysis. Also, ignore @switch annotation.")
   val XfullLubs         = BooleanSetting ("-Xfull-lubs", "Retains pre 2.10 behavior of less aggressive truncation of least upper bounds.")
@@ -222,9 +219,8 @@ trait ScalaSettings extends AbsScalaSettings
   val YdisableUnreachablePrevention = BooleanSetting("-Ydisable-unreachable-prevention", "Disable the prevention of unreachable blocks in code generation.")
   val YnoLoadImplClass = BooleanSetting   ("-Yno-load-impl-class", "Do not load $class.class files.")
 
-  val exposeEmptyPackage = BooleanSetting("-Yexpose-empty-package", "Internal only: expose the empty package.").internalOnly()
-  // the current standard is "inline" but we are moving towards "method"
-  val Ydelambdafy        = ChoiceSetting     ("-Ydelambdafy", "strategy", "Strategy used for translating lambdas into JVM code.", List("inline", "method"), "inline")
+  val exposeEmptyPackage = BooleanSetting ("-Yexpose-empty-package", "Internal only: expose the empty package.").internalOnly()
+  val Ydelambdafy        = ChoiceSetting  ("-Ydelambdafy", "strategy", "Strategy used for translating lambdas into JVM code.", List("inline", "method"), "method")
 
   val YskipInlineInfoAttribute = BooleanSetting("-Yskip-inline-info-attribute", "Do not add the ScalaInlineInfo attribute to classfiles generated by -Ybackend:GenASM")
 
@@ -357,7 +353,7 @@ trait ScalaSettings extends AbsScalaSettings
    */
   val Ybackend = ChoiceSetting ("-Ybackend", "choice of bytecode emitter", "Choice of bytecode emitter.",
                                 List("GenASM", "GenBCode"),
-                                "GenASM")
+                                "GenBCode")
   // Feature extensions
   val XmacroSettings          = MultiStringSetting("-Xmacro-settings", "option", "Custom settings for macros.")
 
@@ -388,6 +384,23 @@ trait ScalaSettings extends AbsScalaSettings
     val Normal = "normal"
     val Discard = "discard"
   }
+
+  def conflictWarning: Option[String] = {
+    def oldOptimiseFlagsInGenBCode: Option[String] = {
+      val optFlags: List[Setting] = if (optimise.value) List(optimise) else optimiseSettings.filter(_.value)
+      if (isBCodeActive && optFlags.nonEmpty) {
+        val msg = s"""Compiler settings for the 2.11 optimizer (${optFlags.map(_.name).mkString(", ")}) are incompatible with -Ybackend:GenBCode (which is the default in 2.12).
+                     |The optimizer settings are ignored. See -Yopt:help for enabling the new optimizer in 2.12.""".stripMargin
+        Some(msg)
+      } else
+        None
+    }
+
+    List(oldOptimiseFlagsInGenBCode /*, moreToCome */).flatten match {
+      case Nil => None
+      case warnings => Some("Conflicting compiler settings were detected. Some settings will be ignored.\n" + warnings.mkString("\n"))
+    }
+  }
 }
 
 object ClassPathRepresentationType {