Allow per-choice help in ChoiceSetting

3 files changed, 28 insertions, 13 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala
index 8386722b63..9d643825f6 100644
--- a/src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala
@@ -30,8 +30,8 @@ trait AbsScalaSettings {
   type OutputSetting <: Setting
 
   def BooleanSetting(name: String, descr: String): BooleanSetting
-  def ChoiceSetting(name: String, helpArg: String, descr: String, choices: List[String], default: String): ChoiceSetting
-  def ChoiceSettingForcedDefault(name: String, helpArg: String, descr: String, choices: List[String], default: String): ChoiceSetting
+  def ChoiceSetting(name: String, helpArg: String, descr: String, choices: List[String], default: String, choicesHelp: List[String] = Nil): ChoiceSetting
+  def ChoiceSettingForcedDefault(name: String, helpArg: String, descr: String, choices: List[String], default: String, choicesHelp: List[String] = Nil): 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[E <: MultiChoiceEnumeration](name: String, helpArg: String, descr: String, domain: E, default: Option[List[String]]): MultiChoiceSetting[E]
diff --git a/src/compiler/scala/tools/nsc/settings/MutableSettings.scala b/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
index 45b21f6126..7b4c55c2af 100644
--- a/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
@@ -219,10 +219,10 @@ class MutableSettings(val errorFn: String => Unit)
   }
 
   def BooleanSetting(name: String, descr: String) = add(new BooleanSetting(name, descr))
-  def ChoiceSetting(name: String, helpArg: String, descr: String, choices: List[String], default: String) =
-    add(new ChoiceSetting(name, helpArg, descr, choices, default))
-  def ChoiceSettingForcedDefault(name: String, helpArg: String, descr: String, choices: List[String], default: String) =
-    ChoiceSetting(name, helpArg, descr, choices, default).withPostSetHook(sett =>
+  def ChoiceSetting(name: String, helpArg: String, descr: String, choices: List[String], default: String, choicesHelp: List[String]) =
+    add(new ChoiceSetting(name, helpArg, descr, choices, default, choicesHelp))
+  def ChoiceSettingForcedDefault(name: String, helpArg: String, descr: String, choices: List[String], default: String, choicesHelp: List[String]) =
+    ChoiceSetting(name, helpArg, descr, choices, default, choicesHelp).withPostSetHook(sett =>
       if (sett.value != default) {
         sett.withDeprecationMessage(s"${name}:${sett.value} is deprecated, forcing use of $default")
         sett.value = default
@@ -627,7 +627,7 @@ class MutableSettings(val errorFn: String => Unit)
     descr: String,
     val domain: E,
     val default: Option[List[String]]
-  ) extends Setting(name, s"$descr: `_' for all, `$name:help' to list") with Clearable {
+  ) extends Setting(name, s"$descr: `_' for all, `$name:help' to list choices.") with Clearable {
 
     withHelpSyntax(s"$name:<_,$helpArg,-$helpArg>")
 
@@ -808,18 +808,33 @@ class MutableSettings(val errorFn: String => Unit)
     helpArg: String,
     descr: String,
     override val choices: List[String],
-    val default: String)
-  extends Setting(name, descr + choices.mkString(" (", ",", ") default:" + default)) {
+    val default: String,
+    val choicesHelp: List[String])
+  extends Setting(name,
+    if (choicesHelp.isEmpty) s"$descr Choices: ${choices.mkString("(", ",", ")")}, default: $default."
+    else s"$descr Default: `$default', `help' to list choices.") {
     type T = String
     protected var v: T = default
     def indexOfChoice: Int = choices indexOf value
 
-    private def usageErrorMessage = f"Usage: $name:<$helpArg>%n where <$helpArg> choices are ${choices mkString ", "} (default: $default)%n"
+    private def choicesHelpMessage = if (choicesHelp.isEmpty) "" else {
+      val choiceLength = choices.map(_.length).max + 1
+      val formatStr = s"  %-${choiceLength}s %s%n"
+      choices.zipAll(choicesHelp, "", "").map({
+        case (choice, desc) => formatStr.format(choice, desc)
+      }).mkString("")
+    }
+    private def usageErrorMessage = f"Usage: $name:<$helpArg> where <$helpArg> choices are ${choices mkString ", "} (default: $default).%n$choicesHelpMessage"
+
+    private var sawHelp = false
+    override def isHelping = sawHelp
+    override def help = usageErrorMessage
 
     def tryToSet(args: List[String]) = errorAndValue(usageErrorMessage, None)
 
     override def tryToSetColon(args: List[String]) = args match {
       case Nil                            => errorAndValue(usageErrorMessage, None)
+      case List("help")                   => sawHelp = true; Some(Nil)
       case List(x) if choices contains x  => value = x ; Some(Nil)
       case List(x)                        => errorAndValue("'" + x + "' is not a valid choice for '" + name + "'", None)
       case xs                             => errorAndValue("'" + name + "' does not accept multiple arguments.", None)
diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 6a164f0e1d..bb1d760d86 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -143,7 +143,7 @@ trait ScalaSettings extends AbsScalaSettings
   val Xxml = MultiChoiceSetting(
     name    = "-Xxml",
     helpArg = "property",
-    descr   = "Configure XML parsing",
+    descr   = "Configure XML parsing.",
     domain  = XxmlSettings
   )
 
@@ -169,7 +169,7 @@ trait ScalaSettings extends AbsScalaSettings
   val Ycompacttrees   = BooleanSetting    ("-Ycompact-trees", "Use compact tree printer when displaying trees.")
   val noCompletion    = BooleanSetting    ("-Yno-completion", "Disable tab-completion in the REPL.")
   val debug           = BooleanSetting    ("-Ydebug", "Increase the quantity of debugging output.")
-  val termConflict    = ChoiceSetting     ("-Yresolve-term-conflict", "strategy", "Resolve term conflicts", List("package", "object", "error"), "error")
+  val termConflict    = ChoiceSetting     ("-Yresolve-term-conflict", "strategy", "Resolve term conflicts.", List("package", "object", "error"), "error")
   val log             = PhasesSetting     ("-Ylog", "Log operations during")
   val Ylogcp          = BooleanSetting    ("-Ylog-classpath", "Output information about what classpath is being applied.")
   val Ynogenericsig   = BooleanSetting    ("-Yno-generic-signatures", "Suppress generation of generic signatures for Java.")
@@ -193,7 +193,7 @@ trait ScalaSettings extends AbsScalaSettings
   val Yrangepos       = BooleanSetting    ("-Yrangepos", "Use range positions for syntax trees.")
   val Ymemberpos      = StringSetting     ("-Yshow-member-pos", "output style", "Show start and end positions of members", "") withPostSetHook (_ => Yrangepos.value = true)
   val Yreifycopypaste = BooleanSetting    ("-Yreify-copypaste", "Dump the reified trees in copypasteable representation.")
-  val Ymacroexpand    = ChoiceSetting     ("-Ymacro-expand", "policy", "Control expansion of macros, useful for scaladoc and presentation compiler", List(MacroExpand.Normal, MacroExpand.None, MacroExpand.Discard), MacroExpand.Normal)
+  val Ymacroexpand    = ChoiceSetting     ("-Ymacro-expand", "policy", "Control expansion of macros, useful for scaladoc and presentation compiler.", List(MacroExpand.Normal, MacroExpand.None, MacroExpand.Discard), MacroExpand.Normal)
   val Ymacronoexpand  = BooleanSetting    ("-Ymacro-no-expand", "Don't expand macros. Might be useful for scaladoc and presentation compiler, but will crash anything which uses macros and gets past typer.") withDeprecationMessage(s"Use ${Ymacroexpand.name}:${MacroExpand.None}") withPostSetHook(_ => Ymacroexpand.value = MacroExpand.None)
   val Yreplsync       = BooleanSetting    ("-Yrepl-sync", "Do not use asynchronous code for repl startup")
   val Yreplclassbased = BooleanSetting    ("-Yrepl-class-based", "Use classes to wrap REPL snippets instead of objects")