Revert "temporarily disables run/reflection-sync-subtypes"

This reverts commit 04e2dbb29830d0e511cdfa8c132a9fad91d657ed,
by avoiding the ill-fated attempt to short-circuit the global
reflection lock.

I think we can do better performance wise, but lets at least
get something correct to start with.

2 files changed, 20 insertions, 0 deletions

diff --git a/test/files/run/reflection-sync-subtypes.check b/test/files/run/reflection-sync-subtypes.check
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/test/files/run/reflection-sync-subtypes.check
diff --git a/test/files/run/reflection-sync-subtypes.scala b/test/files/run/reflection-sync-subtypes.scala
new file mode 100644
index 0000000000..7f75a464ac
--- /dev/null
+++ b/test/files/run/reflection-sync-subtypes.scala
@@ -0,0 +1,20 @@
+import scala.reflect.runtime.universe._
+
+object Test extends App {
+  val n = 1000
+  val rng = new scala.util.Random()
+  val tasks = List(
+    () => typeOf[List[Int]] <:< typeOf[List[T] forSome { type T }],
+    () => typeOf[List[T] forSome { type T }] <:< typeOf[List[Any]],
+    () => typeOf[Map[Int, Object]] <:< typeOf[Iterable[(Int, String)]],
+    () => typeOf[Expr[Any] { val mirror: rootMirror.type }] <:< typeOf[Expr[List[List[List[Int]]]]{ val mirror: rootMirror.type }])
+  val perms = tasks.permutations.toList
+  val diceRolls = List.fill(n)(rng.nextInt(perms.length))
+  val threads = (1 to n) map (i => new Thread(s"Reflector-$i") {
+    override def run(): Unit = {
+      val result = perms(diceRolls(i - 1)).map(_())
+      assert(result.sorted == List(false, false, true, true))
+    }
+  })
+  threads foreach (_.start)
+}
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