From 52521ea6070d907f77ceab0692f804f52c29ffca Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 5 Apr 2017 22:45:23 +0200
Subject: Add child annotations for enum values

A new kind of child annotation that points to the term symbol representing an
enum value.
---
 .../dotty/tools/dotc/transform/IsInstanceOfEvaluator.scala    |  3 +++
 compiler/src/dotty/tools/dotc/transform/PostTyper.scala       | 11 +++++++----
 tests/run/enum-Color.scala                                    |  4 ++++
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/transform/IsInstanceOfEvaluator.scala b/compiler/src/dotty/tools/dotc/transform/IsInstanceOfEvaluator.scala
index ebd2ae436..b48d219d6 100644
--- a/compiler/src/dotty/tools/dotc/transform/IsInstanceOfEvaluator.scala
+++ b/compiler/src/dotty/tools/dotc/transform/IsInstanceOfEvaluator.scala
@@ -147,6 +147,9 @@ class IsInstanceOfEvaluator extends MiniPhaseTransform { thisTransformer =>
             (scTrait && selTrait)
 
           val inMatch = s.qualifier.symbol is Case
+            // FIXME: This will misclassify case objects! We need to find another way to characterize
+            // isInstanceOfs generated by matches.
+            // Probably the most robust way is to use another symbol for the isInstanceOf method.
 
           if (valueClassesOrAny) tree
           else if (knownStatically)
diff --git a/compiler/src/dotty/tools/dotc/transform/PostTyper.scala b/compiler/src/dotty/tools/dotc/transform/PostTyper.scala
index 9821757e8..a0fe55a5b 100644
--- a/compiler/src/dotty/tools/dotc/transform/PostTyper.scala
+++ b/compiler/src/dotty/tools/dotc/transform/PostTyper.scala
@@ -104,8 +104,14 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
     private def transformAnnot(annot: Annotation)(implicit ctx: Context): Annotation =
       annot.derivedAnnotation(transformAnnot(annot.tree))
 
+    private def registerChild(sym: Symbol, tp: Type)(implicit ctx: Context) = {
+      val cls = tp.classSymbol
+      if (cls.is(Sealed)) cls.addAnnotation(Annotation.makeChild(sym))
+    }
+
     private def transformMemberDef(tree: MemberDef)(implicit ctx: Context): Unit = {
       val sym = tree.symbol
+      if (sym.is(CaseVal, butNot = Module | Method)) registerChild(sym, sym.info)
       sym.transformAnnotations(transformAnnot)
     }
 
@@ -227,10 +233,7 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer  { thisTran
 
             // Add Child annotation to sealed parents unless current class is anonymous
             if (!sym.isAnonymousClass) // ignore anonymous class
-              for (parent <- sym.asClass.classInfo.classParents) {
-                val pclazz = parent.classSymbol
-                if (pclazz.is(Sealed)) pclazz.addAnnotation(Annotation.makeChild(sym))
-              }
+              sym.asClass.classInfo.classParents.foreach(registerChild(sym, _))
 
             tree
           }
diff --git a/tests/run/enum-Color.scala b/tests/run/enum-Color.scala
index 683d18d9e..f4f6aaef8 100644
--- a/tests/run/enum-Color.scala
+++ b/tests/run/enum-Color.scala
@@ -7,5 +7,9 @@ object Test {
     for (color <- Color.enumValues) {
       println(s"$color: ${color.enumTag}")
       assert(Color.enumValue(color.enumTag) eq color)
+      import Color._
+      color match {
+        case Red | Green | Blue =>
+      }
     }
 }
-- 
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