From 40df94841921e91d3f4b86bcbc1506495b9d316e Mon Sep 17 00:00:00 2001
From: Yedidya Feldblum <yfeldblum@fb.com>
Date: Fri, 1 Mar 2019 17:58:09 -0800
Subject: [PATCH] Support C++11 in folly/IPAddress.h w.r.t. aligned_union

Summary: [Folly] Support C++11 in `folly/IPAddress.h` w.r.t. `aligned_union` by avoiding `aligned_union_t`, which is C++14.

Reviewed By: spalamarchuk, mengz0

Differential Revision: D14278604

fbshipit-source-id: 474ac0aa0110f4939d1042d334b69feb6b2644cb
---
 folly/IPAddress.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/folly/IPAddress.h b/folly/IPAddress.h
index 18e03f69a7c..91e0f0249e4 100644
--- a/folly/IPAddress.h
+++ b/folly/IPAddress.h
@@ -20,8 +20,10 @@
 #include <iosfwd>
 #include <memory>
 #include <string>
+#include <type_traits>
 #include <utility> // std::pair
 
+#include <folly/ConstexprMath.h>
 #include <folly/IPAddressException.h>
 #include <folly/IPAddressV4.h>
 #include <folly/IPAddressV6.h>
@@ -442,7 +444,10 @@ class IPAddress {
   [[noreturn]] void asV6Throw() const;
 
   typedef union IPAddressV46 {
-    std::aligned_union_t<0, IPAddressV4, IPAddressV6> storage;
+    std::aligned_storage<
+        constexpr_max(sizeof(IPAddressV4), sizeof(IPAddressV6)),
+        constexpr_max(alignof(IPAddressV4), alignof(IPAddressV6))>::type
+        storage;
     IPAddressV4 ipV4Addr;
     IPAddressV6 ipV6Addr;
     // default constructor