Escape chars when printing strings in decompiler

compiler/src/dotty/tools/dotc/core/StdNames.scala

@@ -688,7 +688,7 @@ object StdNames {
   class ScalaTermNames extends ScalaNames[TermName] {
     protected implicit def fromString(s: String): TermName = termName(s)
 
-    @switch def syntheticParamName(i: Int): TermName = i match {
+    def syntheticParamName(i: Int): TermName = (i: @switch) match {
       case 0  => x_0
       case 1  => x_1
       case 2  => x_2
@@ -702,7 +702,7 @@ object StdNames {
       case _  => termName("x$" + i)
     }
 
-    @switch def productAccessorName(j: Int): TermName = j match {
+    def productAccessorName(j: Int): TermName = (j: @switch) match {
       case 1  => nme._1
       case 2  => nme._2
       case 3  => nme._3

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

@@ -443,7 +443,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
 
   def toText(denot: Denotation): Text = toText(denot.symbol) ~ "/D"
 
-  @switch private def escapedChar(ch: Char): String = ch match {
+  private def escapedChar(ch: Char): String = (ch: @switch) match {
     case '\b' => "\\b"
     case '\t' => "\\t"
     case '\n' => "\\n"

compiler/src/dotty/tools/dotc/quoted/Toolbox.scala

@@ -1,13 +1,8 @@
 package dotty.tools.dotc.quoted
 
 import dotty.tools.dotc.ast.tpd
-import dotty.tools.dotc.core.Contexts.Context
-import dotty.tools.dotc.core.Constants._
-import dotty.tools.dotc.core.quoted.PickledQuotes
-import dotty.tools.dotc.printing.RefinedPrinter
 
 import scala.quoted.Expr
-import scala.runtime.BoxedUnit
 import scala.quoted.Exprs.{LiftedExpr, TastyTreeExpr}
 import scala.runtime.quoted._
 
@@ -32,20 +27,7 @@ object Toolbox {
         new QuoteDriver().run(expr, runSettings)
     }
 
-    def show(expr: Expr[T]): String = expr match {
-      case expr: LiftedExpr[T] =>
-        expr.value match {
-          case value: Class[_] => s"classOf[${value.getCanonicalName}]"
-          case value if value == BoxedUnit.UNIT => "()"
-          case value =>
-            implicit val ctx = new QuoteDriver().initCtx
-            if (showSettings.compilerArgs.contains("-color:never"))
-              ctx.settings.color.update("never")
-            val printer = new RefinedPrinter(ctx)
-            printer.toText(Literal(Constant(value))).mkString(Int.MaxValue, false)
-        }
-      case _ => new QuoteDriver().show(expr, showSettings)
-    }
+    def show(expr: Expr[T]): String = new QuoteDriver().show(expr, showSettings)
 
   }
 

library/src/scala/tasty/util/ShowSourceCode.scala

@@ -1,6 +1,8 @@
 package scala.tasty
 package util
 
+import scala.annotation.switch
+
 class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty0) {
   import tasty._
 
@@ -591,8 +593,8 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
       case Constant.Long(v) => this += v += "L"
       case Constant.Float(v) => this += v
       case Constant.Double(v) => this += v
-      case Constant.Char(v) => this += '\'' += v.toString += '\'' // TODO escape char
-      case Constant.String(v) => this += '"' += v.toString += '"' // TODO escape string
+      case Constant.Char(v) => this += '\'' += escapedChar(v) += '\''
+      case Constant.String(v) => this += '"' += escapedString(v) += '"'
     }
 
     def printTypeOrBoundsTree(tpt: TypeOrBoundsTree): Buffer = tpt match {
@@ -770,6 +772,19 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
     def +=(x: Char): this.type = { sb.append(x); this }
     def +=(x: String): this.type = { sb.append(x); this }
 
+    private def escapedChar(ch: Char): String = (ch: @switch) match {
+      case '\b' => "\\b"
+      case '\t' => "\\t"
+      case '\n' => "\\n"
+      case '\f' => "\\f"
+      case '\r' => "\\r"
+      case '"' => "\\\""
+      case '\'' => "\\\'"
+      case '\\' => "\\\\"
+      case _ => if (ch.isControl) "\\0" + Integer.toOctalString(ch) else String.valueOf(ch)
+    }
+
+    private def escapedString(str: String): String = str flatMap escapedChar
   }