From 61ba3c11be5e7831bdb659fc0c35979910c3f637 Mon Sep 17 00:00:00 2001
From: Yedidya Feldblum <yfeldblum@fb.com>
Date: Thu, 2 Nov 2017 19:44:08 -0700
Subject: [PATCH] Alias std::launder when it is available

Summary: [Folly] Alias `std::launder` when it is available.

Reviewed By: Orvid

Differential Revision: D6221443

fbshipit-source-id: 33136a8744a39db01fb05513d5ed5476ea67559a
---
 folly/lang/Launder.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/folly/lang/Launder.h b/folly/lang/Launder.h
index fb0e5f7a..b54d7e68 100644
--- a/folly/lang/Launder.h
+++ b/folly/lang/Launder.h
@@ -16,9 +16,26 @@
 
 #pragma once
 
+#include <new>
+
 #include <folly/CPortability.h>
 #include <folly/Portability.h>
 
+/***
+ *  include or backport:
+ *  * std::launder
+ */
+
+#if __cpp_lib_launder >= 201606
+
+namespace folly {
+
+/* using override */ using std::launder;
+
+} // namespace folly
+
+#else
+
 namespace folly {
 
 /**
@@ -54,3 +71,5 @@ void launder(void const volatile*) = delete;
 template <typename T, typename... Args>
 void launder(T (*)(Args...)) = delete;
 } // namespace folly
+
+#endif
-- 
2.34.1