Make printFresh a -Y option

Author: odersky

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -449,6 +449,7 @@ private sealed trait YSettings:
   val YccDebug: Setting[Boolean] = BooleanSetting(ForkSetting, "Ycc-debug", "Used in conjunction with captureChecking language import, debug info for captured references.")
   val YccNew: Setting[Boolean] = BooleanSetting(ForkSetting, "Ycc-new", "Used in conjunction with captureChecking language import, try out new variants (debug option)")
   val YccLog: Setting[Boolean] = BooleanSetting(ForkSetting, "Ycc-log", "Used in conjunction with captureChecking language import, print tracing and debug info")
+  val YccPrintFresh: Setting[Boolean] = BooleanSetting(ForkSetting, "Ycc-print-fresh", "Print hidden sets of fresh `cap` instances")
   val YccPrintSetup: Setting[Boolean] = BooleanSetting(ForkSetting, "Ycc-print-setup", "Used in conjunction with captureChecking language import, print trees after cc.Setup phase")
 
   /** Area-specific debug output */

compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -28,7 +28,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
   protected def printDebug = ctx.settings.YprintDebug.value
 
   /** Print Fresh.Cap instances as <cap hiding ...> */
-  protected def printFreshDetailed = printDebug
+  protected def printFreshDetailed = ctx.settings.YccPrintFresh.value
 
   /** Print Fresh.Cap instances as "fresh" */
   protected def printFresh = printFreshDetailed || ctx.property(PrintFresh).isDefined