Use Enumeration for MultiChoiceSetting

This is pretty easy, since a ValueSet is a BitSet.

When the setting is updated, recompute the current
set of values, which is cheap and succinct.

Checking a flag is also easy and fast.

Choices in MultiChoiceSettings may enable other choices.

1 files changed, 14 insertions, 10 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala
index cd2cb183b3..6b339b2a6d 100644
--- a/src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala
@@ -7,20 +7,24 @@ package scala
 package tools.nsc
 package settings
 
+import scala.language.higherKinds
+
 trait AbsScalaSettings {
   self: AbsSettings =>
 
+  type MultiChoiceEnumeration <: Enumeration
+
   type Setting <: AbsSetting
 
-  type BooleanSetting     <: Setting { type T = Boolean }
-  type ChoiceSetting      <: Setting { type T = String }
-  type IntSetting         <: Setting { type T = Int }
-  type MultiStringSetting <: Setting { type T = List[String] }
-  type MultiChoiceSetting <: Setting { type T = List[String] }
-  type PathSetting        <: Setting { type T = String }
-  type PhasesSetting      <: Setting { type T = List[String] }
-  type StringSetting      <: Setting { type T = String }
-  type PrefixSetting      <: Setting { type T = List[String] }
+  type BooleanSetting                                  <: Setting { type T = Boolean }
+  type ChoiceSetting                                   <: Setting { type T = String }
+  type IntSetting                                      <: Setting { type T = Int }
+  type MultiStringSetting                              <: Setting { type T = List[String] }
+  type MultiChoiceSetting[E <: MultiChoiceEnumeration] <: Setting { type T <: E#ValueSet }
+  type PathSetting                                     <: Setting { type T = String }
+  type PhasesSetting                                   <: Setting { type T = List[String] }
+  type StringSetting                                   <: Setting { type T = String }
+  type PrefixSetting                                   <: Setting { type T = List[String] }
 
   type OutputDirs
   type OutputSetting <: Setting
@@ -29,7 +33,7 @@ trait AbsScalaSettings {
   def ChoiceSetting(name: String, helpArg: String, descr: String, choices: List[String], default: String): ChoiceSetting
   def IntSetting(name: String, descr: String, default: Int, range: Option[(Int, Int)], parser: String => Option[Int]): IntSetting
   def MultiStringSetting(name: String, helpArg: String, descr: String): MultiStringSetting
-  def MultiChoiceSetting(name: String, helpArg: String, descr: String, choices: List[String], descriptions: List[String], default: Option[List[String]]): MultiChoiceSetting
+  def MultiChoiceSetting[E <: MultiChoiceEnumeration](name: String, helpArg: String, descr: String, domain: E, default: Option[List[String]]): MultiChoiceSetting[E]
   def OutputSetting(outputDirs: OutputDirs, default: String): OutputSetting
   def PathSetting(name: String, descr: String, default: String): PathSetting
   def PhasesSetting(name: String, descr: String, default: String): PhasesSetting