From: Phil Willoughby <philwill@fb.com>
Date: Thu, 6 Jul 2017 07:09:18 +0000 (-0700)
Subject: launder
X-Git-Tag: v2017.07.10.00~6
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=folly.git;a=commitdiff_plain;h=1eee8628ee22c2382f7617e13eb5039bff7c9258

launder

Summary: Backport C++17's `std::launder`.

Reviewed By: yfeldblum, ot

Differential Revision: D5370531

fbshipit-source-id: b7cc6701d082b6c4855fa77bb644e151ce882deb
---

diff --git a/folly/Utility.h b/folly/Utility.h
index d84abb7b..dbe552f0 100644
--- a/folly/Utility.h
+++ b/folly/Utility.h
@@ -260,4 +260,11 @@ class MoveOnly {
 
 using MoveOnly = moveonly_::MoveOnly;
 
+/**
+ * Backport from C++17 of std::launder
+ */
+template <typename T>
+constexpr T* launder(T* in) {
+  return (in + 1) - 1;
+}
 } // namespace folly