From abc6950f4edba9fd1ce6784171144cdd66c00caf Mon Sep 17 00:00:00 2001
From: Guillaume Martres <smarter@ubuntu.com>
Date: Wed, 18 Mar 2015 19:06:00 +0100
Subject: [PATCH] Add Phases#atInitialPhaseOf and use it where needed

Using it in isDerivedValueClass fixes the bug showcased in #411.
---
 .../tools/backend/jvm/DottyBackendInterface.scala     | 11 +++++------
 src/dotty/tools/dotc/core/Phases.scala                |  7 +++++++
 src/dotty/tools/dotc/transform/ValueClasses.scala     |  4 +++-
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/src/dotty/tools/backend/jvm/DottyBackendInterface.scala b/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
index 111a5f5f518a..fe1c7104b563 100644
--- a/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
+++ b/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
@@ -478,12 +478,11 @@ class DottyBackendInterface()(implicit ctx: Context) extends BackendInterface{
     def originalOwner: Symbol = {
       try {
         if (sym.exists) {
-          val original = toDenot(sym).initial
-          val validity = original.validFor
-          val shiftedContext = ctx.withPhase(validity.phaseId)
-          val r = toDenot(sym)(shiftedContext).maybeOwner
-          if(r is Flags.Package) NoSymbol
-          else r
+          ctx.atInitialPhaseOf(toDenot(sym)) { implicit ctx =>
+            val r = toDenot(sym).maybeOwner
+            if (r is Flags.Package) NoSymbol
+            else r
+          }
         } else NoSymbol
       } catch {
         case e: NotDefinedHere => NoSymbol // todo: do we have a method to tests this?
diff --git a/src/dotty/tools/dotc/core/Phases.scala b/src/dotty/tools/dotc/core/Phases.scala
index bf2b34f3c903..ea36546f0fda 100644
--- a/src/dotty/tools/dotc/core/Phases.scala
+++ b/src/dotty/tools/dotc/core/Phases.scala
@@ -32,6 +32,13 @@ trait Phases {
 
   def atNextPhase[T](op: Context => T): T = atPhase(phase.next)(op)
 
+  /** Execute `op` at the earliest phase were `ref` was valid */
+  def atInitialPhaseOf[T](ref: SingleDenotation)(op: Context => T): T = {
+    val original = ref.initial
+    val initialId = original.validFor.phaseId
+    atPhase(initialId)(op)
+  }
+
   def atPhaseNotLaterThan[T](limit: Phase)(op: Context => T): T =
     if (!limit.exists || phase <= limit) op(this) else atPhase(limit)(op)
 
diff --git a/src/dotty/tools/dotc/transform/ValueClasses.scala b/src/dotty/tools/dotc/transform/ValueClasses.scala
index c2239e3f69c3..43e6ff1468f6 100644
--- a/src/dotty/tools/dotc/transform/ValueClasses.scala
+++ b/src/dotty/tools/dotc/transform/ValueClasses.scala
@@ -13,10 +13,12 @@ import StdNames._
 object ValueClasses {
 
   def isDerivedValueClass(d: SymDenotation)(implicit ctx: Context) =
-    d.isClass &&
+    ctx.atInitialPhaseOf(d) { implicit ctx =>
+      d.isClass &&
       d.derivesFrom(defn.AnyValClass) &&
       (d.symbol ne defn.AnyValClass) &&
       !d.isPrimitiveValueClass
+    }
 
   def isMethodWithExtension(d: SymDenotation)(implicit ctx: Context) =
     d.isSourceMethod &&