make values array lazy when not static

Author: bishabosha

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

@@ -117,8 +117,9 @@ object DesugarEnums {
     val rawEnumClassRef = rawRef(enumClass.typeRef)
     extension (tpe: NamedType) def ofRawEnum = AppliedTypeTree(ref(tpe), rawEnumClassRef)
 
+    val lazyFlagOpt = if enumCompanion.owner.isStatic then EmptyFlags else Lazy
     val privateValuesDef = ValDef(nme.DOLLAR_VALUES, TypeTree(), ArrayLiteral(enumValues, rawEnumClassRef))
-      .withFlags(Private | Synthetic)
+      .withFlags(Private | Synthetic | lazyFlagOpt)
 
     val valuesDef =
       DefDef(nme.values, Nil, Nil, defn.ArrayType.ofRawEnum, valuesDot(nme.clone_))

tests/run/enums-thunk.scala

@@ -0,0 +1,27 @@
+class Outer {
+  val thunk = { () =>
+    enum E { case A1 }
+    E.A1
+  }
+  val thunk2 = { () =>
+    enum E { case A2 }
+    E.values
+  }
+}
+
+object Outer2 {
+  val thunk = { () =>
+    enum E { case B1 }
+    E.B1
+  }
+  val thunk2 = { () =>
+    enum E { case B2 }
+    E.values
+  }
+}
+
+@main def Test =
+  assert(Outer().thunk().toString == "A1")
+  assert(Outer().thunk2()(0).toString == "A2")
+  assert(Outer2.thunk().toString == "B1")
+  assert(Outer2.thunk2()(0).toString == "B2")