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.

2 files changed, 29 insertions, 0 deletions

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)
+    })
+  }
+}