SI-8708 Fix pickling of LOCAL_CHILD child of sealed classes

When a sealed class or trait has local children, they are not pickled
in as part of the children of the symbol (introduced in 12a2b3b to fix
Aladdin bug 1055). Instead the compiler adds a single child class
named LOCAL_CHILD. The parents of its ClassInfoType were wrong: the
first parent should be a class. For sealed traits, we were using the
trait itself.

Also, the LOCAL_CHILD dummy class was entered as a member of its
enclosing class, which is wrong: it represents a local (non-member)
class, and it's a synthetic dummy anyway.

9 files changed, 75 insertions, 0 deletions

diff --git a/test/files/neg/aladdin1055.check b/test/files/neg/aladdin1055.check
new file mode 100644
index 0000000000..41782ae987
--- /dev/null
+++ b/test/files/neg/aladdin1055.check
@@ -0,0 +1,7 @@
+Test_1.scala:2: warning: match may not be exhaustive.
+It would fail on the following input: (_ : this.<local child>)
+  def foo(t: A.T) = t match {
+                    ^
+error: No warnings can be incurred under -Xfatal-warnings.
+one warning found
+one error found
diff --git a/test/files/neg/aladdin1055.flags b/test/files/neg/aladdin1055.flags
new file mode 100644
index 0000000000..e8fb65d50c
--- /dev/null
+++ b/test/files/neg/aladdin1055.flags
@@ -0,0 +1 @@
+-Xfatal-warnings
\ No newline at end of file
diff --git a/test/files/neg/aladdin1055/A.scala b/test/files/neg/aladdin1055/A.scala
new file mode 100644
index 0000000000..862336e30c
--- /dev/null
+++ b/test/files/neg/aladdin1055/A.scala
@@ -0,0 +1,6 @@
+object A {
+  sealed trait T { def f: Int }
+  class TT extends T { def f = 0 }
+
+  def foo = new T { def f = 1 } // local subclass of sealed trait T
+}
diff --git a/test/files/neg/aladdin1055/Test_1.scala b/test/files/neg/aladdin1055/Test_1.scala
new file mode 100644
index 0000000000..39d9b1dc98
--- /dev/null
+++ b/test/files/neg/aladdin1055/Test_1.scala
@@ -0,0 +1,5 @@
+object Test {
+  def foo(t: A.T) = t match {
+    case a: A.TT => 0
+  }
+}
diff --git a/test/files/pos/t8708/Either_1.scala b/test/files/pos/t8708/Either_1.scala
new file mode 100644
index 0000000000..000ed6e7c2
--- /dev/null
+++ b/test/files/pos/t8708/Either_1.scala
@@ -0,0 +1,6 @@
+sealed trait \/[+A, +B]
+
+sealed trait EitherT[F[+_], +A, +B]
+object EitherT {
+  def apply[F[+_], A, B](a: F[A \/ B]): EitherT[F, A, B] = new EitherT[F, A, B] { val run = a }
+}
diff --git a/test/files/pos/t8708/Test_2.scala b/test/files/pos/t8708/Test_2.scala
new file mode 100644
index 0000000000..d0e56b9a37
--- /dev/null
+++ b/test/files/pos/t8708/Test_2.scala
@@ -0,0 +1,13 @@
+import scala.language.higherKinds
+
+trait ClientTypes[M[+_]] {
+  final type Context[+A] = EitherT[M, String, A]
+  object Context {
+    def apply[A](ca: M[String \/ A]): Context[A] = EitherT[M, String, A](ca)
+  }
+
+  final type StatefulContext[+A] = EitherT[Context, String, A]
+  object StatefulContext {
+    def apply[A](state: Context[String \/ A]): StatefulContext[A] = ???
+  }
+}
diff --git a/test/files/run/t8708_b.check b/test/files/run/t8708_b.check
new file mode 100644
index 0000000000..30be62a307
--- /dev/null
+++ b/test/files/run/t8708_b.check
@@ -0,0 +1,8 @@
+Scope{
+  def <init>: <?>;
+  sealed abstract trait T extends ;
+  def foo: <?>
+}
+Scope{
+  def f: <?>
+}
diff --git a/test/files/run/t8708_b/A_1.scala b/test/files/run/t8708_b/A_1.scala
new file mode 100644
index 0000000000..e767420f9e
--- /dev/null
+++ b/test/files/run/t8708_b/A_1.scala
@@ -0,0 +1,8 @@
+package p
+
+class C {
+
+  sealed trait T { def f: Int }
+
+  def foo: T = new T { def f = 1 }
+}
diff --git a/test/files/run/t8708_b/Test_2.scala b/test/files/run/t8708_b/Test_2.scala
new file mode 100644
index 0000000000..c978490609
--- /dev/null
+++ b/test/files/run/t8708_b/Test_2.scala
@@ -0,0 +1,21 @@
+import scala.tools.partest._
+import java.io.{Console => _, _}
+
+object Test extends DirectTest {
+
+  override def extraSettings: String = "-usejavacp -cp " + testOutput.path
+
+  override def code = ""
+
+  override def show(): Unit = {
+    val g = newCompiler()
+    withRun(g)(r => {
+      val c = g.rootMirror.getRequiredClass("p.C")
+      println(c.info.decls)
+      val t = c.info.member(g.newTypeName("T"))
+      // this test ensrues that the <local child> dummy class symbol is not entered in the
+      // scope of trait T during unpickling.
+      println(t.info.decls)
+    })
+  }
+}