Merge pull request #2270 from retronym/ticket/7246-2

SI-7246 Make $outer pointer elision Java aware

9 files changed, 99 insertions, 22 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
index f6ee7be511..970519ab7c 100644
--- a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
@@ -45,26 +45,24 @@ abstract class ExplicitOuter extends InfoTransform
   private def isInner(clazz: Symbol) =
     !clazz.isPackageClass && !clazz.outerClass.isStaticOwner
 
-  private def haveSameOuter(parent: Type, clazz: Symbol) = parent match {
-    case TypeRef(pre, sym, _)   =>
-      val owner = clazz.owner
+  private def haveSameOuter(parent: Type, clazz: Symbol) = {
+    val owner = clazz.owner
+    val parentSym = parent.typeSymbol
 
-      //println(s"have same outer $parent $clazz $sym ${sym.owner} $owner $pre")
-
-      sym.isClass && owner.isClass &&
-      (owner isSubClass sym.owner) &&
-      owner.thisType =:= pre
-
-    case _                      => false
+    parentSym.isClass && owner.isClass &&
+      (owner isSubClass parentSym.owner) &&
+      owner.thisType =:= parent.prefix
   }
 
   /** Does given clazz define an outer field? */
   def hasOuterField(clazz: Symbol) = {
-    val parents = clazz.info.parents
+    val parent = clazz.info.firstParent
 
-    isInner(clazz) && !clazz.isTrait && {
-      parents.isEmpty || !haveSameOuter(parents.head, clazz)
-    }
+    // space optimization: inherit the $outer pointer from the parent class if
+    // we know that it will point to the correct instance.
+    def canReuseParentOuterField = !parent.typeSymbol.isJavaDefined && haveSameOuter(parent, clazz)
+
+    isInner(clazz) && !clazz.isTrait && !canReuseParentOuterField
   }
 
   private def outerField(clazz: Symbol): Symbol = {
diff --git a/test/files/run/outertest.scala b/test/files/run/outertest.scala
index 3cc96afa5b..fa0443f669 100644
--- a/test/files/run/outertest.scala
+++ b/test/files/run/outertest.scala
@@ -1,26 +1,57 @@
 // A test for the case where the outer field of class B#J should be eliminated.
-// You can verify this by running a javap on B.J
+
+import reflect.ClassTag
+
 abstract class A {
+  abstract class I
 
-  abstract class I {
+  val foo = this
+}
 
+class B extends A {
+  class J extends I {
+    val bar = foo
   }
 
-  val foo = "foo"
+  type II = I
+  class K extends II {
+    val bar = foo
+  }
 
+  class L extends (I @annotation.tailrec) {
+    val bar = foo
+  }
 }
 
-class B extends A {
 
-  class J extends I {
+class C extends A {
+  val c: C = this
+
+  class M extends c.I {
     val bar = foo
   }
-
 }
 
-object  Test extends App {
 
+object Test extends App {
   val b = new B
-  assert((new b.J).bar == b.foo)
+  val c0 = new C
+  val c = new { override val c = c0 } with C
+
+  assert((new b.J).bar eq b)
+  assert((new b.K).bar eq b)
+  assert((new b.L).bar eq b)
+  assert((new c.M).bar eq c)
+
+  def checkOuterFields[C: ClassTag](expected: Int) {
+    val cls = implicitly[ClassTag[C]].runtimeClass
+    val outerFields = cls.getDeclaredFields().filter(_.getName.contains("$outer"))
+    assert(outerFields.size == expected, outerFields.map(_.getName))
+  }
 
+  checkOuterFields[A#I](1) // the base class must have the $outer pointer
+  checkOuterFields[B#J](0) // reuse parent class' $outer pointer
+  checkOuterFields[B#K](0) // ... through an alias
+  checkOuterFields[B#L](0) // ... through the annotated type
+  checkOuterFields[C#M](1) // different prefix, can't share.
 }
diff --git a/test/files/run/t7246.check b/test/files/run/t7246.check
new file mode 100755
index 0000000000..ce01362503
--- /dev/null
+++ b/test/files/run/t7246.check
@@ -0,0 +1 @@
+hello
diff --git a/test/files/run/t7246/Outer.java b/test/files/run/t7246/Outer.java
new file mode 100755
index 0000000000..163276fb3b
--- /dev/null
+++ b/test/files/run/t7246/Outer.java
@@ -0,0 +1,4 @@
+public class Outer {
+    public class Inner {
+    }
+}
\ No newline at end of file
diff --git a/test/files/run/t7246/Test.scala b/test/files/run/t7246/Test.scala
new file mode 100755
index 0000000000..9f23ca8f3a
--- /dev/null
+++ b/test/files/run/t7246/Test.scala
@@ -0,0 +1,16 @@
+object Test extends App {
+
+  val so = new SubOuter
+  val si = new so.SubInner
+  println(si.bar)
+}
+
+class SubOuter extends Outer {
+
+  val foo = "hello"
+
+  class SubInner extends Inner {
+    def bar = foo
+  }
+
+}
\ No newline at end of file
diff --git a/test/files/run/t7246b.check b/test/files/run/t7246b.check
new file mode 100755
index 0000000000..5073bd8617
--- /dev/null
+++ b/test/files/run/t7246b.check
@@ -0,0 +1,2 @@
+base
+sub
diff --git a/test/files/run/t7246b/Base.scala b/test/files/run/t7246b/Base.scala
new file mode 100755
index 0000000000..4e71d3313d
--- /dev/null
+++ b/test/files/run/t7246b/Base.scala
@@ -0,0 +1,7 @@
+class Base {
+  val baseOuter = "base"
+
+  class BaseInner {
+    val baseInner = baseOuter
+  }
+}
diff --git a/test/files/run/t7246b/Outer.java b/test/files/run/t7246b/Outer.java
new file mode 100755
index 0000000000..53a79316ef
--- /dev/null
+++ b/test/files/run/t7246b/Outer.java
@@ -0,0 +1,4 @@
+public class Outer extends Base {
+    public class Inner extends BaseInner {
+    }
+}
\ No newline at end of file
diff --git a/test/files/run/t7246b/Test.scala b/test/files/run/t7246b/Test.scala
new file mode 100755
index 0000000000..f0982ea8d0
--- /dev/null
+++ b/test/files/run/t7246b/Test.scala
@@ -0,0 +1,14 @@
+object Test extends App {
+
+  val so = new SubOuter
+  val si = new so.SubInner
+  println(si.baseInner)
+  println(si.subInner)
+}
+
+class SubOuter extends Outer {
+  val subOuter = "sub"
+  class SubInner extends Inner {
+    def subInner = subOuter
+  }
+}