From f5edd7dcaf8308a946d3843940e2f7a5f40ca44f Mon Sep 17 00:00:00 2001
From: Christopher Dykes <cdykes@fb.com>
Date: Mon, 20 Nov 2017 13:44:02 -0800
Subject: [PATCH] Work around a bug in MSVC name lookup within templated friend
 contexts

Summary: MSVC has a bug that causes it to think that `once_flag` in this context resolves to the `using` statement further up, rather than `detail::once_flag`.

Reviewed By: yfeldblum

Differential Revision: D6376501

fbshipit-source-id: 481dbd75ed21f3d519bd920258fa743f314668ad
---
 folly/synchronization/CallOnce.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/folly/synchronization/CallOnce.h b/folly/synchronization/CallOnce.h
index 4d4bf0f4..51543ea2 100644
--- a/folly/synchronization/CallOnce.h
+++ b/folly/synchronization/CallOnce.h
@@ -83,12 +83,12 @@ class once_flag {
 
   template <typename Mutex_, typename Callable, class... Args>
   friend void ::folly::call_once(
-      once_flag<Mutex_>& flag,
+      detail::once_flag<Mutex_>& flag,
       Callable&& f,
       Args&&... args);
   template <typename Mutex_, typename Callable, class... Args>
   friend void call_once_impl_no_inline(
-      once_flag<Mutex_>& flag,
+      detail::once_flag<Mutex_>& flag,
       Callable&& f,
       Args&&... args);
 
-- 
2.34.1