fix: Drop copied parent refinements before generating bytecode

compiler/src/dotty/tools/dotc/Compiler.scala

@@ -132,6 +132,7 @@ class Compiler {
          new ElimStaticThis,         // Replace `this` references to static objects by global identifiers
          new CountOuterAccesses) ::  // Identify outer accessors that can be dropped
     List(new DropOuterAccessors,     // Drop unused outer accessors
+         new DropParentRefinements,  // Drop parent refinements from a template
          new CheckNoSuperThis,       // Check that supercalls don't contain references to `this`
          new Flatten,                // Lift all inner classes to package scope
          new TransformWildcards,     // Replace wildcards with default values

compiler/src/dotty/tools/dotc/transform/DropParentRefinements.scala

@@ -0,0 +1,35 @@
+package dotty.tools.dotc.transform
+
+import dotty.tools.dotc.transform.MegaPhase.MiniPhase
+import dotty.tools.dotc.ast.tpd
+import dotty.tools.dotc.core.Contexts.Context
+import dotty.tools.dotc.core.DenotTransformers.IdentityDenotTransformer
+import dotty.tools.dotc.typer.Typer
+
+object DropParentRefinements:
+  val name: String = "dropParentRefinements"
+  val description: String = "drop parent refinements from a template"
+
+/** Drop parent refinements from a template. because they are generated without
+  * an implementation. These refinements are unusally required for tracked
+  * members with more specific types.
+  */
+class DropParentRefinements extends MiniPhase with IdentityDenotTransformer:
+  thisPhase =>
+  import tpd.*
+
+  override def phaseName: String = DropParentRefinements.name
+
+  override def description: String = DropParentRefinements.description
+
+  override def runsAfterGroupsOf: Set[String] = Set(CountOuterAccesses.name)
+
+  override def changesMembers: Boolean = true // the phase drops parent refinements
+
+  override def transformTemplate(tree: tpd.Template)(using Context): tpd.Tree =
+    val newBody = tree.body.filter(!_.hasAttachment(Typer.RefinementFromParent))
+    tree.body.foreach { member =>
+      if member.hasAttachment(Typer.RefinementFromParent) then
+        member.symbol.dropAfter(thisPhase)
+    }
+    cpy.Template(tree)(body = newBody)

compiler/src/dotty/tools/dotc/transform/Getters.scala

@@ -103,7 +103,7 @@ class Getters extends MiniPhase with SymTransformer { thisPhase =>
   override def transformValDef(tree: ValDef)(using Context): Tree =
     val sym = tree.symbol
     if !sym.is(Method) then return tree
-    val getterDef = DefDef(sym.asTerm, tree.rhs).withSpan(tree.span)
+    val getterDef = DefDef(sym.asTerm, tree.rhs).withSpan(tree.span).withAttachmentsFrom(tree)
     if !sym.is(Mutable) then return getterDef
     ensureSetter(sym.asTerm)
     if !newSetters.contains(sym.setter) then return getterDef

compiler/src/dotty/tools/dotc/typer/Namer.scala

@@ -877,16 +877,16 @@ class Namer { typer: Typer =>
     protected def addAnnotations(sym: Symbol): Unit = original match {
       case original: untpd.MemberDef =>
         lazy val annotCtx = annotContext(original, sym)
-        original.setMods: 
+        original.setMods:
           original.mods.withAnnotations :
-            original.mods.annotations.mapConserve: annotTree =>  
+            original.mods.annotations.mapConserve: annotTree =>
               val cls = typedAheadAnnotationClass(annotTree)(using annotCtx)
               if (cls eq sym)
                 report.error(em"An annotation class cannot be annotated with iself", annotTree.srcPos)
                 annotTree
               else
-                val ann = 
-                  if cls.is(JavaDefined) then Checking.checkNamedArgumentForJavaAnnotation(annotTree, cls.asClass) 
+                val ann =
+                  if cls.is(JavaDefined) then Checking.checkNamedArgumentForJavaAnnotation(annotTree, cls.asClass)
                   else annotTree
                 val ann1 = Annotation.deferred(cls)(typedAheadExpr(ann)(using annotCtx))
                 sym.addAnnotation(ann1)

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -78,6 +78,9 @@ object Typer {
   /** An attachment for GADT constraints that were inferred for a pattern. */
   val InferredGadtConstraints = new Property.StickyKey[core.GadtConstraint]
 
+  /** Inducates that a definition was copied over from the parent refinements */
+  val RefinementFromParent = new Property.StickyKey[Unit]
+
   /** An attachment on a Select node with an `apply` field indicating that the `apply`
    *  was inserted by the Typer.
    */
@@ -3081,7 +3084,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
             ( if sym.isType then TypeDef(sym.asType)
               else if sym.is(Method) then DefDef(sym.asTerm)
               else ValDef(sym.asTerm)
-            ).withSpan(impl.span.startPos)
+            ).withSpan(impl.span.startPos).withAttachment(RefinementFromParent, ())
           body ++ refinements
         case None =>
           body

tests/run/i21213-min.check

@@ -0,0 +1 @@
+bar

tests/run/i21213-min.scala

@@ -0,0 +1,9 @@
+import scala.language.experimental.modularity
+import scala.language.future
+
+sealed abstract class Foo(tracked val discriminator: String)
+class Bar extends Foo("bar")
+
+val bar: Foo = Bar()
+object Test extends App:
+  println(bar.discriminator)

tests/run/i21213.check

@@ -0,0 +1 @@
+bar

tests/run/i21213.scala

@@ -0,0 +1,10 @@
+import scala.language.experimental.modularity
+import scala.language.future
+
+enum Foo(tracked val discriminator: String):
+  case Bar() extends Foo("bar")
+  case Baz() extends Foo("baz")
+
+val bar: Foo = Foo.Bar()
+object Test extends App:
+  println(bar.discriminator)