SI-8525 MultiChoice takes a helper function

Clean-up code review comments.

MultiChoice takes a helper function for outputting help text.

1 files changed, 21 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 6675ad96e6..5c3eadbd60 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -70,8 +70,27 @@ trait ScalaSettings extends AbsScalaSettings
   // Would be nice to build this dynamically from scala.languageFeature.
   // The two requirements: delay error checking until you have symbols, and let compiler command build option-specific help.
   val language      = {
-    val features = List("dynamics", "postfixOps", "reflectiveCalls", "implicitConversions", "higherKinds", "existentials", "experimental.macros")
-    MultiChoiceSetting("-language", "feature", "Enable or disable language features", features)
+    val features = List(
+      "dynamics"            -> "Allow direct or indirect subclasses of scala.Dynamic",
+      "postfixOps"          -> "Allow postfix operator notation, such as `1 to 10 toList'",
+      "reflectiveCalls"     -> "Allow reflective access to members of structural types",
+      "implicitConversions" -> "Allow definition of implicit functions called views",
+      "higherKinds"         -> "Allow higher-kinded types",  // "Ask Adriaan, but if you have to ask..."
+      "existentials"        -> "Existential types (besides wildcard types) can be written and inferred",
+      "experimental.macros" -> "Allow macro defintion (besides implementation and application)"
+    )
+    val description = "Enable or disable language features"
+    MultiChoiceSetting(
+      name    = "-language",
+      helpArg = "feature",
+      descr   = description,
+      choices = features map (_._1)
+    ) { s =>
+      val helpline: ((String, String)) => String = {
+        case (name, text) => f"  $name%-25s $text%n"
+      }
+      features map helpline mkString (f"$description:%n", "", f"%n")
+    }
   }
 
   /*