Group settings should honor user-set individual options

In the last commit, we added the ability to explicitly disable
boolean settings form the command line.

This commit changes group settings (like -optimize), to leave
them alone if set explicitly.

Examples:

   `scalac -Xlint -Ywarn-unused:false -optimize -Yinline:false`

The mechanism for such settings has also been refactored to
`MutableSettings`, to let use reuse this for `-Xlint`.

3 files changed, 18 insertions, 24 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/MutableSettings.scala b/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
index a8421c8b15..3590254128 100644
--- a/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
@@ -679,4 +679,14 @@ class MutableSettings(val errorFn: String => Unit)
       else name + "[:phases]"
     )
   }
+
+  /** Internal use - syntax enhancements. */
+  protected class EnableSettings[T <: BooleanSetting](val s: T) {
+    def enablingIfNotSetByUser(toEnable: List[BooleanSetting]): s.type = s withPostSetHook (_ => toEnable foreach (sett => if (!sett.isSetByUser) sett.value = s.value))
+    def enabling(toEnable: List[BooleanSetting]): s.type = s withPostSetHook (_ => toEnable foreach (_.value = s.value))
+    def disabling(toDisable: List[BooleanSetting]): s.type = s withPostSetHook (_ => toDisable foreach (_.value = !s.value))
+    def andThen(f: s.T => Unit): s.type = s withPostSetHook (setting => f(setting.value))
+  }
+  import scala.language.implicitConversions
+  protected implicit def installEnableSettings[T <: BooleanSetting](s: T): EnableSettings[T] = new EnableSettings(s)
 }
diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 57aa8243b6..a643a08614 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -47,14 +47,6 @@ trait ScalaSettings extends AbsScalaSettings
   /** Is an info setting set? */
   def isInfo = infoSettings exists (_.isSetByUser)
 
-  /** Internal use - syntax enhancements. */
-  private class EnableSettings[T <: BooleanSetting](val s: T) {
-    def enabling(toEnable: List[BooleanSetting]): s.type = s withPostSetHook (_ => toEnable foreach (_.value = s.value))
-    def disabling(toDisable: List[BooleanSetting]): s.type = s withPostSetHook (_ => toDisable foreach (_.value = !s.value))
-    def andThen(f: s.T => Unit): s.type                  = s withPostSetHook (setting => f(setting.value))
-  }
-  private implicit def installEnableSettings[T <: BooleanSetting](s: T) = new EnableSettings(s)
-
   /** Disable a setting */
   def disable(s: Setting) = allSettings -= s
 
@@ -216,10 +208,10 @@ trait ScalaSettings extends AbsScalaSettings
 
   /** Groups of Settings.
    */
-  val future        = BooleanSetting("-Xfuture", "Turn on future language features.") enabling futureSettings
-  val optimise      = BooleanSetting("-optimise", "Generates faster bytecode by applying optimisations to the program") withAbbreviation "-optimize" enabling optimiseSettings
+  val future        = BooleanSetting("-Xfuture", "Turn on future language features.") enablingIfNotSetByUser futureSettings
+  val optimise      = BooleanSetting("-optimise", "Generates faster bytecode by applying optimisations to the program") withAbbreviation "-optimize" enablingIfNotSetByUser optimiseSettings
   val nooptimise    = BooleanSetting("-Ynooptimise", "Clears all the flags set by -optimise. Useful for testing optimizations in isolation.") withAbbreviation "-Ynooptimize" disabling optimise::optimiseSettings
-  val Xexperimental = BooleanSetting("-Xexperimental", "Enable experimental extensions.") enabling experimentalSettings
+  val Xexperimental = BooleanSetting("-Xexperimental", "Enable experimental extensions.") enablingIfNotSetByUser experimentalSettings
 
   /**
    * Settings motivated by GenBCode
diff --git a/src/compiler/scala/tools/nsc/settings/Warnings.scala b/src/compiler/scala/tools/nsc/settings/Warnings.scala
index 5214f6485f..1509ad13b8 100644
--- a/src/compiler/scala/tools/nsc/settings/Warnings.scala
+++ b/src/compiler/scala/tools/nsc/settings/Warnings.scala
@@ -7,6 +7,8 @@ package scala.tools
 package nsc
 package settings
 
+import language.existentials
+
 /** Settings influencing the printing of warnings.
  */
 trait Warnings {
@@ -34,19 +36,6 @@ trait Warnings {
     // warnUnusedImport currently considered too noisy for general use
   )
 
-  // Warning groups.
-  val lint = (
-    BooleanSetting("-Xlint", "Enable recommended additional warnings.")
-    withPostSetHook (_ => lintWarnings foreach (_.value = true))
-  )
-
-  /*val warnEverything = */ (
-    BooleanSetting("-Ywarn-all", "Enable all -Y warnings.")
-    withPostSetHook { _ =>
-      lint.value = true
-      allWarnings foreach (_.value = true)
-    }
-  )
   private lazy val warnSelectNullable = BooleanSetting("-Xcheck-null", "This option is obsolete and does nothing.")
 
   // Individual warnings.
@@ -61,6 +50,9 @@ trait Warnings {
   val warnUnused           = BooleanSetting   ("-Ywarn-unused", "Warn when local and private vals, vars, defs, and types are are unused")
   val warnUnusedImport     = BooleanSetting   ("-Ywarn-unused-import", "Warn when imports are unused")
 
+   // Warning groups.
+  val lint = BooleanSetting("-Xlint", "Enable recommended additional warnings.") enablingIfNotSetByUser lintWarnings
+
   // Backward compatibility.
   @deprecated("Use fatalWarnings", "2.11.0") def Xwarnfatal            = fatalWarnings      // used by sbt
   @deprecated("This option is being removed", "2.11.0") def Xchecknull = warnSelectNullable // used by ide