Fix #3932: ANSI color leak in repl

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

@@ -169,7 +169,9 @@ class PlainPrinter(_ctx: Context) extends Printer {
         "<noprefix>"
       case tp: MethodType =>
         changePrec(GlobalPrec) {
-          (if (tp.isImplicitMethod) "(implicit " else "(") ~ paramsText(tp) ~
+          ("(" + (if (tp.isErasedMethod)   "erased "   else "")
+               + (if (tp.isImplicitMethod) "implicit " else "")
+          ) ~ paramsText(tp) ~
           (if (tp.resultType.isInstanceOf[MethodType]) ")" else "): ") ~
           toText(tp.resultType)
         }
@@ -536,9 +538,9 @@ class PlainPrinter(_ctx: Context) extends Printer {
   protected def literalText(text: Text): Text = coloredText(text, SyntaxHighlighting.LiteralColor)
   protected def stringText(text: Text): Text = coloredText(text, SyntaxHighlighting.StringColor)
 
-  private def coloredStr(text: String, color: String): String =
+  protected def coloredStr(text: String, color: String): String =
     if (ctx.useColors) color + text + SyntaxHighlighting.NoColor else text
-  private def coloredText(text: Text, color: String): Text =
+  protected def coloredText(text: Text, color: String): Text =
     if (ctx.useColors) color ~ text ~ SyntaxHighlighting.NoColor else text
 }
 

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

@@ -37,4 +37,9 @@ class ReplPrinter(_ctx: Context) extends DecompilerPrinter(_ctx) {
       else ":" ~~ toText(sym.info)
     }
   }
+
+  // We don't want the colors coming from RefinedPrinter as the REPL uses its
+  // own syntax coloring mechanism.
+  override def coloredStr(text: String, color: String): String = text
+  override def coloredText(text: Text, color: String): Text = text
 }

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

@@ -31,7 +31,7 @@ object SyntaxHighlighting {
   private val tripleQs = Console.RED_B + "???" + NoColor
 
   private val keywords: Seq[String] = for {
-    index <- IF to ENUM // All alpha keywords
+    index <- IF to ERASED // All alpha keywords
   } yield tokenString(index)
 
   private val interpolationPrefixes =

compiler/test-resources/repl/3932

@@ -0,0 +1,2 @@
+scala> def fun[T](x: T): implicit List[T] => Int = ???
+def fun[T](x: T): implicit List[T] => Int

compiler/test-resources/repl/erased

@@ -0,0 +1,2 @@
+scala> def f(erased a: Int): Int = ???
+def f(erased a: Int): Int

compiler/test-resources/repl/erased-implicit

@@ -0,0 +1,2 @@
+scala> def f(erased implicit a: Int): Int = ???
+def f(erased implicit a: Int): Int