Merge pull request #5397 from retronym/ticket/9920

SI-9920 Avoid linkage errors with captured local objects + self types

7 files changed, 84 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
index f3d5ceb0f0..7d50c12852 100644
--- a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
@@ -8,7 +8,7 @@ package tools.nsc
 package transform
 
 import symtab._
-import Flags.{ CASE => _, _ }
+import Flags.{CASE => _, _}
 import scala.collection.mutable.ListBuffer
 
 /** This class ...
diff --git a/src/compiler/scala/tools/nsc/transform/LambdaLift.scala b/src/compiler/scala/tools/nsc/transform/LambdaLift.scala
index 74e6c58388..10d9c5627b 100644
--- a/src/compiler/scala/tools/nsc/transform/LambdaLift.scala
+++ b/src/compiler/scala/tools/nsc/transform/LambdaLift.scala
@@ -319,7 +319,14 @@ abstract class LambdaLift extends InfoTransform {
           else if (clazz.isStaticOwner) gen.mkAttributedQualifier(clazz.thisType)
           else outerValue match {
             case EmptyTree => prematureSelfReference()
-            case o         => outerPath(o, currentClass.outerClass, clazz)
+            case o         =>
+              val path = outerPath(o, currentClass.outerClass, clazz)
+              if (path.tpe <:< clazz.tpeHK) path
+              else {
+                // SI-9920 The outer accessor might have an erased type of the self type of a trait,
+                //         rather than the trait itself. Add a cast if necessary.
+                gen.mkAttributedCast(path, clazz.tpeHK)
+              }
           }
         }
 
diff --git a/test/files/pos/t9920.scala b/test/files/pos/t9920.scala
new file mode 100644
index 0000000000..8612618cc4
--- /dev/null
+++ b/test/files/pos/t9920.scala
@@ -0,0 +1,6 @@
+object Test {
+  def o = {
+    def i: Int = { i; 0 }
+    i
+  }
+}
diff --git a/test/files/run/t9920.scala b/test/files/run/t9920.scala
new file mode 100644
index 0000000000..5dc32e99b7
--- /dev/null
+++ b/test/files/run/t9920.scala
@@ -0,0 +1,17 @@
+class C0
+trait T { self: C0 =>
+  def test = {
+    object Local
+
+    class C1 {
+      Local
+    }
+    new C1()
+  }
+}
+
+object Test extends C0 with T {
+  def main(args: Array[String]): Unit = {
+    test
+  }
+}
diff --git a/test/files/run/t9920b.scala b/test/files/run/t9920b.scala
new file mode 100644
index 0000000000..fab196b669
--- /dev/null
+++ b/test/files/run/t9920b.scala
@@ -0,0 +1,17 @@
+class C0
+trait T {
+  def test = {
+    object Local
+
+    class C1 {
+      Local
+    }
+    new C1()
+  }
+}
+
+object Test extends C0 with T {
+  def main(args: Array[String]): Unit = {
+    test
+  }
+}
diff --git a/test/files/run/t9920c.scala b/test/files/run/t9920c.scala
new file mode 100644
index 0000000000..9541dc650a
--- /dev/null
+++ b/test/files/run/t9920c.scala
@@ -0,0 +1,21 @@
+class C0
+trait T { self: C0 =>
+  def test = {
+    object Local
+
+    class C2 {
+      class C1 {
+        Local
+      }
+      T.this.toString
+      new C1
+    }
+    new C2()
+  }
+}
+
+object Test extends C0 with T {
+  def main(args: Array[String]): Unit = {
+    test
+  }
+}
diff --git a/test/files/run/t9920d.scala b/test/files/run/t9920d.scala
new file mode 100644
index 0000000000..debc99e199
--- /dev/null
+++ b/test/files/run/t9920d.scala
@@ -0,0 +1,14 @@
+class C { object O }
+trait T { _: C =>
+  def foo {
+    class D { O }
+    new D
+  }
+}
+
+
+object Test extends C with T {
+  def main(args: Array[String]): Unit = {
+    foo
+  }
+}