From e7c9fce1f1297bbf7d5f71d2e1c1503a5299d00d Mon Sep 17 00:00:00 2001
From: Jasper Moeys <jaspermoeys@hotmail.com>
Date: Fri, 28 Sep 2018 13:22:56 +0200
Subject: [PATCH 1/2] Fix #5044: guard against forward references in the
 TypeTree of New trees

---
 compiler/src/dotty/tools/dotc/typer/RefChecks.scala | 8 ++++++--
 tests/neg/i5044a.scala                              | 7 +++++++
 tests/neg/i5044b.scala                              | 8 ++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 tests/neg/i5044a.scala
 create mode 100644 tests/neg/i5044b.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
index 5f04152c62b1..d25617da85c8 100644
--- a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -1010,9 +1010,14 @@ class RefChecks extends MiniPhase { thisPhase =>
   }
 
   override def transformNew(tree: New)(implicit ctx: Context) = {
-    val sym = tree.tpe.typeSymbol
+    val tpe = tree.tpe
+    val sym = tpe.typeSymbol
     checkUndesiredProperties(sym, tree.pos)
     currentLevel.enterReference(sym, tree.pos)
+    tpe.dealias.foreachPart {
+      case TermRef(_, s: Symbol) => currentLevel.enterReference(s, tree.pos)
+      case _ =>
+    }
     tree
   }
 }
@@ -1643,4 +1648,3 @@ class RefChecks extends MiniPhase { thisPhase =>
       }
     }
 */
-
diff --git a/tests/neg/i5044a.scala b/tests/neg/i5044a.scala
new file mode 100644
index 000000000000..897c9e5e6d96
--- /dev/null
+++ b/tests/neg/i5044a.scala
@@ -0,0 +1,7 @@
+class I0 {
+  class I1
+  def i3 = {
+    val i4 = new i5.I1 // error: `i5` is a forward reference extending over the definition of `i4`
+    val i5 = new I0
+  }
+}
diff --git a/tests/neg/i5044b.scala b/tests/neg/i5044b.scala
new file mode 100644
index 000000000000..1e1391b8d0a7
--- /dev/null
+++ b/tests/neg/i5044b.scala
@@ -0,0 +1,8 @@
+class I0 {
+  class I1
+  def i3 = {
+    type T = i5.I1
+    val i4 = new T // error: `i5` is a forward reference extending over the definition of `i4`
+    val i5 = new I0
+  }
+}

From 91eaf201d97e5e774cea98bb43918e143fd022e3 Mon Sep 17 00:00:00 2001
From: Jasper Moeys <jaspermoeys@hotmail.com>
Date: Fri, 28 Sep 2018 16:45:03 +0200
Subject: [PATCH 2/2] address review

---
 tests/neg/i5044.scala  | 26 ++++++++++++++++++++++++++
 tests/neg/i5044a.scala |  7 -------
 tests/neg/i5044b.scala |  8 --------
 3 files changed, 26 insertions(+), 15 deletions(-)
 create mode 100644 tests/neg/i5044.scala
 delete mode 100644 tests/neg/i5044a.scala
 delete mode 100644 tests/neg/i5044b.scala

diff --git a/tests/neg/i5044.scala b/tests/neg/i5044.scala
new file mode 100644
index 000000000000..efcfdd31db64
--- /dev/null
+++ b/tests/neg/i5044.scala
@@ -0,0 +1,26 @@
+class I0 {
+  class I1
+  def test0 = {
+    val x = new y.I1 // error: `y` is a forward reference extending over the definition of `x`
+    val y = new I0
+  }
+
+  def test1 = {
+    type T = y.I1
+    val x = new T // error: `y` is a forward reference extending over the definition of `x`
+    val y = new I0
+  }
+
+  class I2[T1, T2]
+  def test2 = {
+    type A[T] = y.I2[T, String]
+    val x = new A[Int] // error: `y` is a forward reference extending over the definition of `x`
+    val y = new I0
+  }
+
+  def test3 = {
+    val x = new T // error: `T` is a forward reference extending over the definition of `x`
+    val y = new I0
+    type T = y.I1
+  }
+}
diff --git a/tests/neg/i5044a.scala b/tests/neg/i5044a.scala
deleted file mode 100644
index 897c9e5e6d96..000000000000
--- a/tests/neg/i5044a.scala
+++ /dev/null
@@ -1,7 +0,0 @@
-class I0 {
-  class I1
-  def i3 = {
-    val i4 = new i5.I1 // error: `i5` is a forward reference extending over the definition of `i4`
-    val i5 = new I0
-  }
-}
diff --git a/tests/neg/i5044b.scala b/tests/neg/i5044b.scala
deleted file mode 100644
index 1e1391b8d0a7..000000000000
--- a/tests/neg/i5044b.scala
+++ /dev/null
@@ -1,8 +0,0 @@
-class I0 {
-  class I1
-  def i3 = {
-    type T = i5.I1
-    val i4 = new T // error: `i5` is a forward reference extending over the definition of `i4`
-    val i5 = new I0
-  }
-}