Emit unicode instead of octal literals

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

@@ -12,7 +12,6 @@ import typer.Implicits._
 import typer.ImportInfo
 import Variances.varianceSign
 import util.SourcePosition
-import java.lang.Integer.toOctalString
 import scala.util.control.NonFatal
 import scala.annotation.switch
 
@@ -525,7 +524,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
     case '"' => "\\\""
     case '\'' => "\\\'"
     case '\\' => "\\\\"
-    case _ => if (ch.isControl) "\\0" + toOctalString(ch) else String.valueOf(ch)
+    case _ => if (ch.isControl) f"\u${ch.toInt}%04x" else String.valueOf(ch)
   }
 
   def toText(const: Constant): Text = const.tag match {

compiler/src/scala/quoted/runtime/impl/printers/SourceCode.scala

@@ -1413,7 +1413,7 @@ object SourceCode {
       case '"' => "\\\""
       case '\'' => "\\\'"
       case '\\' => "\\\\"
-      case _ => if (ch.isControl) "\\0" + Integer.toOctalString(ch) else String.valueOf(ch)
+      case _ => if (ch.isControl) f"\u${ch.toInt}%04x" else String.valueOf(ch)
     }
 
     private def escapedString(str: String): String = str flatMap escapedChar

tests/run-macros/i13183.check

@@ -0,0 +1,5 @@
+"\u001b"
+"\u0000\u0001\u0003"
+"ABC"
+"\u0080\u0081翿"
+"\t\n\r👋👌🥳"

tests/run-macros/i13183/Macro_1.scala

@@ -0,0 +1,5 @@
+import scala.quoted.*
+
+object Macro_1:
+  inline def stringLiteral(inline s: String): String = ${showExpr('s)}
+  def showExpr(s: Expr[?])(using Quotes): Expr[String] = Expr(s.show.toString)

tests/run-macros/i13183/Test_2.scala

@@ -0,0 +1,6 @@
+@main def Test =
+  println(Macro_1.stringLiteral("\u001b")) // "\u001b"
+  println(Macro_1.stringLiteral("\u0000\u0001\u0003")) // "\u0000\u0001\u0003"
+  println(Macro_1.stringLiteral("A\u0042C")) // "ABC"
+  println(Macro_1.stringLiteral("\u0080\u0081\u7fff")) // "\u0080\u0081翿"
+  println(Macro_1.stringLiteral("\t\n\r👋👌🥳")) // "\t\n\r👋👌🥳"

tests/run/i13183.check

@@ -0,0 +1 @@
+"\u001b"

tests/run/i13183.scala

@@ -0,0 +1,2 @@
+@main def Test(): Unit =
+  println(scala.compiletime.codeOf("\u001b"))