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Author: bishabosha

compiler/src/dotty/tools/dotc/ast/DesugarEnums.scala

@@ -172,6 +172,8 @@ object DesugarEnums {
               :+ default(ordinal)))
 
     if !enumClass.exists then
+      // in the case of a double definition of an enum that only defines class cases (see tests/neg/i4470c.scala)
+      // it seems `enumClass` might be `NoSymbol`; in this case we provide no scaffolding.
       Nil
     else
       scaffolding ::: valueCtor ::: fromOrdinal :: Nil

tests/neg/i4470c.scala

@@ -1,9 +1,31 @@
 object DuplicatedEnum {
+
   enum Maybe[+T] { // error
     case Some[T](x: T) extends Maybe[T]
   }
 
   enum Maybe[+T] { // error
     case Some[T](x: T) extends Maybe[T]
   }
+
+  enum Color { // error
+    case Red, Green, Blue
+  }
+
+  enum Color { // error
+    case Red, Green, Blue
+  }
+
+  enum Tag[T] { // error
+    case Int extends Tag[Int]
+    case OfClass[T]()(using val tag: reflect.ClassTag[T]) extends Tag[T] // mix order of class and value
+    case String extends Tag[String]
+  }
+
+  enum Tag[T] { // error
+    case Int extends Tag[Int]
+    case OfClass[T]()(using val tag: reflect.ClassTag[T]) extends Tag[T] // mix order of class and value
+    case String extends Tag[String]
+  }
+
 }