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.

1 files changed, 9 insertions, 2 deletions

diff --git a/src/reflect/scala/reflect/runtime/SynchronizedSymbols.scala b/src/reflect/scala/reflect/runtime/SynchronizedSymbols.scala
index 298d0ffebd..1a232c8de1 100644
--- a/src/reflect/scala/reflect/runtime/SynchronizedSymbols.scala
+++ b/src/reflect/scala/reflect/runtime/SynchronizedSymbols.scala
@@ -32,8 +32,15 @@ private[reflect] trait SynchronizedSymbols extends internal.Symbols { self: Symb
   trait SynchronizedSymbol extends Symbol {
 
     def gilSynchronizedIfNotInited[T](body: => T): T = {
-      if (isFullyInitialized) body
-      else gilSynchronized { body }
+      // TODO JZ desired, but prone to race conditions. We need the runtime reflection based
+      //      type completers to establish a memory barrier upon initialization. Maybe a volatile
+      //      write? We need to consult with the experts here. Until them, lock pessimistically.
+      //
+      //      `run/reflection-sync-subtypes.scala` fails about 1/50 times otherwise.
+      //
+      //      if (isFullyInitialized) body
+      //      else gilSynchronized { body }
+      gilSynchronized { body }
     }
 
     override def validTo = gilSynchronizedIfNotInited { super.validTo }