Add scala.Symbol constants to Tasty reflect

compiler/src/dotty/tools/dotc/tastyreflect/TastyImpl.scala

@@ -1072,6 +1072,12 @@ class TastyImpl(val rootContext: Contexts.Context) extends scala.tasty.Tasty { s
       }
     }
 
+    object Symbol extends SymbolExtractor {
+      def unapply(x: Constant): Option[scala.Symbol] = x match {
+        case x: Constants.Constant if x.tag == Constants.ScalaSymbolTag => Some(x.scalaSymbolValue)
+        case _ => None
+      }
+    }
   }
 
   // ===== Signature ================================================

compiler/test/dotc/pos-decompilation.blacklist

@@ -1,10 +1,3 @@
-# Constant(Symbol)
-desugar.scala
-sip23-symbols.scala
-t389.scala
-t4812.scala
-t4579.scala
-
 # assertion failed: asTerm called on not-a-Term val <none>
 cls.scala
 escapes2.scala

compiler/test/dotc/run-decompilation.blacklist

@@ -32,14 +32,6 @@ t3651.scala
 protectedacc.scala
 t7436.scala
 
-# Constant(Symbol)
-fors.scala
-t6634.scala
-t6632.scala
-t4601.scala
-t6633.scala
-arrays.scala
-
 # scala.MatchError: SeqLiteral in pattern
 i3248.scala
 t6541.scala

library/src/scala/tasty/Tasty.scala

@@ -825,6 +825,13 @@ abstract class Tasty { tasty =>
     abstract class ClassTagExtractor {
       def unapply(x: Constant): Option[Type]
     }
+
+    /** Extractor for scala.Symbol literals */
+    val Symbol: SymbolExtractor
+    /** Extractor for scala.Symbol literals */
+    abstract class SymbolExtractor {
+      def unapply(x: Constant): Option[scala.Symbol]
+    }
   }
 
   // ===== Signature ================================================

library/src/scala/tasty/util/ShowExtractors.scala

@@ -153,6 +153,7 @@ class ShowExtractors[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
       case Constant.Double(value) => this += "Constant.Double(" += value += ")"
       case Constant.String(value) => this += "Constant.String(\"" += value += "\")"
       case Constant.ClassTag(value) => this += "Constant.ClassTag(" += value += ")"
+      case Constant.Symbol(value) => this += "Constant.Symbol('" += value.name += ")"
     }
 
     def visitType(x: TypeOrBounds): Buffer = x match {

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

@@ -722,6 +722,8 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
       case Constant.ClassTag(v) =>
         this += "classOf"
         inSquare(printType(v))
+      case Constant.Symbol(v) =>
+        this += "'" += v.name
     }
 
     def printTypeOrBoundsTree(tpt: TypeOrBoundsTree): Buffer = tpt match {