Fix printing of value classes

Author: nicolasstucki

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

@@ -459,6 +459,14 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
 
     def printArgDef(arg: ValDef): Unit = {
       val ValDef(name, tpt, rhs) = arg
+      arg.owner.owner match {
+        case ClassDef(_, _, _, _, body) =>
+          body.collectFirst {
+            case vdef @ ValDef(name1, _, _) if name == name1 && vdef.flags.isParamAccessor && !vdef.flags.isLocal =>
+              this += "val "
+          }
+        case _ =>
+      }
       this += name += ": "
       printTypeTree(tpt)
     }
@@ -604,6 +612,8 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
           case prefix@Type.SymRef(ClassDef(_, _, _, _, _), _) =>
             printType(prefix)
             this += "#"
+          case Type.ThisType(Type.SymRef(ClassDef(_, _, _, _, _), _)) =>
+            this += "this."
           case prefix@Type() =>
             printType(prefix)
             this += "."
@@ -625,6 +635,7 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
       case Type.TypeRef(name, prefix) =>
         prefix match {
           case NoPrefix() =>
+          case EmptyPackage() =>
           case prefix@Type() =>
             printType(prefix)
             this += "."

tests/pos/i518.decompiled

@@ -0,0 +1,14 @@
+/** Decompiled from out/posTestFromTasty/pos/i518/Meter.class */
+final class Meter(val underlying: scala.Int) extends scala.AnyVal {
+  override def hashCode(): scala.Int = this.underlying.hashCode()
+  override def equals(x$0: scala.Any): scala.Boolean = x$0 match {
+    case x$0: Meter =>
+      this.underlying.==(x$0.underlying)
+    case _ =>
+      false
+  }
+}
+object Meter extends scala.AnyRef/** Decompiled from out/posTestFromTasty/pos/i518/Test.class */
+class Test() {
+  val x: scala.Int = new Meter(3).hashCode()
+}