From 710e13de39e66cdfabb4b30944daaf1224c2d32b Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Sun, 31 Dec 2017 16:14:56 +0100
Subject: [PATCH 1/2] Fix #3634: Lazily evaluate static module accessors

We did not use lazy evaluation for static objects, because these are usually evauated
lazily by the backend. But that does not hold if the static module is an (accessor) def
instead of a val.
---
 .../src/dotty/tools/dotc/transform/LazyVals.scala     |  7 +++++--
 tests/run/i3634.scala                                 | 11 +++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 tests/run/i3634.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/LazyVals.scala b/compiler/src/dotty/tools/dotc/transform/LazyVals.scala
index 0f930b353e36..11f0211fbad1 100644
--- a/compiler/src/dotty/tools/dotc/transform/LazyVals.scala
+++ b/compiler/src/dotty/tools/dotc/transform/LazyVals.scala
@@ -36,7 +36,7 @@ class LazyVals extends MiniPhase with IdentityDenotTransformer {
   class OffsetInfo(var defs: List[Tree], var ord:Int)
   val appendOffsetDefs = mutable.Map.empty[Symbol, OffsetInfo]
 
-  override def phaseName: String = "LazyVals"
+  override def phaseName: String = "lazyVals"
 
   /** List of names of phases that should have finished processing of tree
     * before this phase starts processing same tree */
@@ -61,7 +61,10 @@ class LazyVals extends MiniPhase with IdentityDenotTransformer {
 
   def transformLazyVal(tree: ValOrDefDef)(implicit ctx: Context): Tree = {
     val sym = tree.symbol
-    if (!(sym is Flags.Lazy) || sym.owner.is(Flags.Trait) || (sym.isStatic && sym.is(Flags.Module))) tree
+    if (!(sym is Flags.Lazy) ||
+        sym.owner.is(Flags.Trait) ||
+        (sym.isStatic && sym.is(Flags.Module, butNot = Flags.Method)))
+      tree
     else {
       val isField = sym.owner.isClass
       if (isField) {
diff --git a/tests/run/i3634.scala b/tests/run/i3634.scala
new file mode 100644
index 000000000000..6889b371fa08
--- /dev/null
+++ b/tests/run/i3634.scala
@@ -0,0 +1,11 @@
+trait T {
+  case object Foo
+}
+
+object Bar extends T
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    assert(Bar.Foo == Bar.Foo) // false
+  }
+}

From 6d84f521edc111ed806c73ca19bb4cfe006e8866 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Sun, 31 Dec 2017 17:43:22 +0100
Subject: [PATCH 2/2] Address review comments

---
 compiler/src/dotty/tools/dotc/transform/LazyVals.scala | 4 ++--
 tests/pending/run/implicits-numeric.scala              | 7 +++++++
 tests/run/{i3634.scala => i3624.scala}                 | 4 +++-
 3 files changed, 12 insertions(+), 3 deletions(-)
 create mode 100644 tests/pending/run/implicits-numeric.scala
 rename tests/run/{i3634.scala => i3624.scala} (58%)

diff --git a/compiler/src/dotty/tools/dotc/transform/LazyVals.scala b/compiler/src/dotty/tools/dotc/transform/LazyVals.scala
index 11f0211fbad1..77fc11d25ab0 100644
--- a/compiler/src/dotty/tools/dotc/transform/LazyVals.scala
+++ b/compiler/src/dotty/tools/dotc/transform/LazyVals.scala
@@ -62,8 +62,8 @@ class LazyVals extends MiniPhase with IdentityDenotTransformer {
   def transformLazyVal(tree: ValOrDefDef)(implicit ctx: Context): Tree = {
     val sym = tree.symbol
     if (!(sym is Flags.Lazy) ||
-        sym.owner.is(Flags.Trait) ||
-        (sym.isStatic && sym.is(Flags.Module, butNot = Flags.Method)))
+        sym.owner.is(Flags.Trait) || // val is accessor, lazy field will be implemented in subclass
+        (sym.isStatic && sym.is(Flags.Module, butNot = Flags.Method))) // static module vals are implemented in the JVM by lazy loading
       tree
     else {
       val isField = sym.owner.isClass
diff --git a/tests/pending/run/implicits-numeric.scala b/tests/pending/run/implicits-numeric.scala
new file mode 100644
index 000000000000..dfb0ff46082a
--- /dev/null
+++ b/tests/pending/run/implicits-numeric.scala
@@ -0,0 +1,7 @@
+object Test extends App {
+
+  implicit def _1: Long = 1L
+  implicit def _2: Int = 0
+
+  println(implicitly[AnyVal])
+}
diff --git a/tests/run/i3634.scala b/tests/run/i3624.scala
similarity index 58%
rename from tests/run/i3634.scala
rename to tests/run/i3624.scala
index 6889b371fa08..b9d20d05a4b0 100644
--- a/tests/run/i3634.scala
+++ b/tests/run/i3624.scala
@@ -3,9 +3,11 @@ trait T {
 }
 
 object Bar extends T
+object Baz extends T
 
 object Test {
   def main(args: Array[String]): Unit = {
-    assert(Bar.Foo == Bar.Foo) // false
+    assert(Bar.Foo eq Bar.Foo)
+    assert(Bar.Foo ne Baz.Foo)
   }
 }