add enumLabel in terms of productPrefix

Author: bishabosha

docs/docs/reference/enums/enums.md

@@ -110,14 +110,17 @@ For a more in-depth example of using Scala 3 enums from Java, see [this test](ht
 ### Implementation
 
 Enums are represented as `sealed` classes that extend the `scala.Enum` trait.
-This trait defines a single public method, `ordinal`:
+This trait defines a two public methods, `ordinal` and `enumLabel`:
 
 ```scala
 package scala
 
 /** A base trait of all enum classes */
 trait Enum extends Product with Serializable {
 
+  /** A string uniquely identifying a case of an enum */
+  final def enumLabel: String = productPrefix
+
   /** A number uniquely identifying a case of an enum */
   def ordinal: Int
 }

library/src-bootstrapped/scala/Enum.scala

@@ -3,5 +3,8 @@ package scala
 /** A base trait of all enum classes */
 trait Enum extends Product, Serializable:
 
+  /** A string uniquely identifying a case of an enum */
+  final def enumLabel: String = productPrefix
+
   /** A number uniquely identifying a case of an enum */
   def ordinal: Int

library/src/scala/runtime/EnumValues.scala

@@ -14,8 +14,7 @@ class EnumValues[E <: Enum] {
 
   def fromInt: Map[Int, E] = myMap
   def fromName: Map[String, E] = {
-    // TODO remove cast when scala.Enum is bootstrapped
-    if (fromNameCache == null) fromNameCache = myMap.values.map(v => v.asInstanceOf[Product].productPrefix -> v).toMap
+    if (fromNameCache == null) fromNameCache = myMap.values.map(v => v.productPrefix -> v).toMap
     fromNameCache
   }
   def values: Iterable[E] = myMap.values

tests/run/enum-custom-toString.scala

@@ -34,25 +34,33 @@ object Tag:
 @main def Test =
   assert(ES.A.toString == "overridden",    s"ES.A.toString = ${ES.A.toString}")
   assert(ES.A.productPrefix == "A",        s"ES.A.productPrefix = ${ES.A.productPrefix}")
+  assert(ES.A.enumLabel == "A",            s"ES.A.enumLabel = ${ES.A.enumLabel}")
   assert(ES.valueOf("A") == ES.A,          s"ES.valueOf(A) = ${ES.valueOf("A")}")
   assert(EJ.B.toString == "overridden",    s"EJ.B.toString = ${EJ.B.toString}")
   assert(EJ.B.productPrefix == "B",        s"EJ.B.productPrefix = ${EJ.B.productPrefix}")
+  assert(EJ.B.enumLabel == "B",            s"EJ.B.enumLabel = ${EJ.B.enumLabel}")
   assert(EJ.valueOf("B") == EJ.B,          s"EJ.valueOf(B) = ${EJ.valueOf("B")}")
   assert(EM.C.toString == "overridden",    s"EM.C.toString = ${EM.C.toString}")
   assert(EM.C.productPrefix == "C",        s"EM.C.productPrefix = ${EM.C.productPrefix}")
+  assert(EM.C.enumLabel == "C",            s"EM.C.enumLabel = ${EM.C.enumLabel}")
   assert(EM.valueOf("C") == EM.C,          s"EM.valueOf(C) = ${EM.valueOf("C")}")
   assert(ET.D.toString == "overridden",    s"ET.D.toString = ${ET.D.toString}")
   assert(ET.D.productPrefix == "D",        s"ET.D.productPrefix = ${ET.D.productPrefix}")
+  assert(ET.D.enumLabel == "D",            s"ET.D.enumLabel = ${ET.D.enumLabel}")
   assert(EZ.E(0).toString == "overridden", s"EZ.E(0).toString = ${EZ.E(0).toString}")
   assert(EZ.E(0).productPrefix == "E",     s"EZ.E(0).productPrefix = ${EZ.E(0).productPrefix}")
+  assert(EZ.E(0).enumLabel == "E",         s"EZ.E(0).enumLabel = ${EZ.E(0).enumLabel}")
   assert(EC.F.toString == "F",             s"EC.F.toString = ${EC.F.toString}")
   assert(EC.F.productPrefix == "F",        s"EC.F.productPrefix = ${EC.F.productPrefix}")
+  assert(EC.F.enumLabel == "F",            s"EC.F.enumLabel = ${EC.F.enumLabel}")
   assert(EC.valueOf("F") == EC.F,          s"EC.valueOf(F) = ${EC.valueOf("F")}")
   assert(EC.G(0).toString == "G(0)",       s"EC.G(0).toString = ${EC.G(0).toString}")
   assert(EC.G(0).productPrefix == "G",     s"EC.G(0).productPrefix = ${EC.G(0).productPrefix}")
+  assert(EC.G(0).enumLabel == "G",         s"EC.G(0).enumLabel = ${EC.G(0).enumLabel}")
 
   assert(
     assertion = Tag.IntTag.toString == s"${Tag.IntTag.getClass.getName}@${Integer.toHexString(123)}",
     message   = s"Tag.IntTag.toString = ${Tag.IntTag.toString}"
   )
   assert(Tag.IntTag.productPrefix == Tag.IntTag.toString, s"Tag.IntTag.productPrefix = ${Tag.IntTag.productPrefix}")
+  assert(Tag.IntTag.enumLabel     == Tag.IntTag.toString, s"Tag.IntTag.enumLabel = ${Tag.IntTag.enumLabel}")