From c30b2db59a097e11a98204a4cf930abc678314a2 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Tue, 9 May 2017 13:09:52 +0200
Subject: [PATCH] Disallow phantom var

---
 .../tools/dotc/transform/FirstTransform.scala |  6 ++--
 tests/neg/phantom-var.scala                   |  8 +++++
 tests/neg/phantom-volitile.scala              |  3 +-
 tests/run/phantom-var-2.check                 |  3 --
 tests/run/phantom-var-2.scala                 | 35 -------------------
 tests/run/phantom-var.check                   |  2 --
 tests/run/phantom-var.scala                   | 30 ----------------
 7 files changed, 14 insertions(+), 73 deletions(-)
 create mode 100644 tests/neg/phantom-var.scala
 delete mode 100644 tests/run/phantom-var-2.check
 delete mode 100644 tests/run/phantom-var-2.scala
 delete mode 100644 tests/run/phantom-var.check
 delete mode 100644 tests/run/phantom-var.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/FirstTransform.scala b/compiler/src/dotty/tools/dotc/transform/FirstTransform.scala
index 469e247a1033..db91ff26705f 100644
--- a/compiler/src/dotty/tools/dotc/transform/FirstTransform.scala
+++ b/compiler/src/dotty/tools/dotc/transform/FirstTransform.scala
@@ -162,8 +162,10 @@ class FirstTransform extends MiniPhaseTransform with InfoTransformer with Annota
   }
 
   override def transformValDef(vdef: tpd.ValDef)(implicit ctx: Context, info: TransformerInfo): tpd.Tree = {
-    if (vdef.symbol.hasAnnotation(defn.VolatileAnnot) && vdef.tpt.tpe.isPhantom)
-      ctx.error("Phantom fields can not be @volatile", vdef.pos)
+    if (vdef.tpt.tpe.isPhantom) {
+      if (vdef.symbol.is(Mutable)) ctx.error("var fields cannot have Phantom types", vdef.pos)
+      else if (vdef.symbol.hasAnnotation(defn.VolatileAnnot)) ctx.error("Phantom fields cannot be @volatile", vdef.pos)
+    }
     vdef
   }
 
diff --git a/tests/neg/phantom-var.scala b/tests/neg/phantom-var.scala
new file mode 100644
index 000000000000..5a7e2db3fdb6
--- /dev/null
+++ b/tests/neg/phantom-var.scala
@@ -0,0 +1,8 @@
+
+class Foo {
+  var foo = Boo.boo // error: var fields cannot have Phantom types
+}
+
+object Boo extends Phantom {
+  def boo = assume
+}
diff --git a/tests/neg/phantom-volitile.scala b/tests/neg/phantom-volitile.scala
index 1fada8572a7a..e8874c035503 100644
--- a/tests/neg/phantom-volitile.scala
+++ b/tests/neg/phantom-volitile.scala
@@ -1,6 +1,7 @@
 
 class Foo {
-  @volatile var foo = Boo.boo // error
+  @volatile var foo1 = Boo.boo // error: var fields cannot have Phantom types
+  @volatile val foo2 = Boo.boo // error: Phantom fields cannot be @volatile
 }
 
 object Boo extends Phantom {
diff --git a/tests/run/phantom-var-2.check b/tests/run/phantom-var-2.check
deleted file mode 100644
index c02f34162f78..000000000000
--- a/tests/run/phantom-var-2.check
+++ /dev/null
@@ -1,3 +0,0 @@
-foo
-foo2
-foo3
diff --git a/tests/run/phantom-var-2.scala b/tests/run/phantom-var-2.scala
deleted file mode 100644
index 1e766df5a935..000000000000
--- a/tests/run/phantom-var-2.scala
+++ /dev/null
@@ -1,35 +0,0 @@
-
-object Test {
-  import Boo._
-
-  def main(args: Array[String]): Unit = {
-    val f = new Foo
-    f.foo
-    f.foo
-    f.foo = {
-      println("foo3")
-      any
-    }
-    f.foo
-    assert(!f.getClass.getDeclaredFields.exists(_.getName.startsWith("foo")), "field foo not erased")
-  }
-}
-
-class Foo {
-  import Boo._
-
-  var foo = {
-    println("foo")
-    any
-  }
-
-  foo = {
-    println("foo2")
-    any
-  }
-}
-
-object Boo extends Phantom {
-  type BooAny = this.Any
-  def any: BooAny = assume
-}
diff --git a/tests/run/phantom-var.check b/tests/run/phantom-var.check
deleted file mode 100644
index b210800439ff..000000000000
--- a/tests/run/phantom-var.check
+++ /dev/null
@@ -1,2 +0,0 @@
-foo
-foo2
diff --git a/tests/run/phantom-var.scala b/tests/run/phantom-var.scala
deleted file mode 100644
index dda20fe92bfe..000000000000
--- a/tests/run/phantom-var.scala
+++ /dev/null
@@ -1,30 +0,0 @@
-
-/* Run this test with
- *   `run tests/run/xyz.scala -Xprint-diff-del -Xprint:arrayConstructors,phantomTermErasure,phantomTypeErasure,erasure`
- * to see the the diffs after PhantomRefErasure, PhantomDeclErasure and Erasure.
- */
-
-object Test {
-  import Boo._
-
-  def main(args: Array[String]): Unit = {
-    foo
-    foo
-    foo = {
-      println("foo2")
-      any
-    }
-    foo
-
-  }
-
-  var foo = {
-    println("foo")
-    any
-  }
-}
-
-object Boo extends Phantom {
-  type BooAny = this.Any
-  def any: BooAny = assume
-}