From 30cbdcb5c3694e2e6c4647ce88df9e3692bf90cf Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne@apple.com>
Date: Wed, 4 Mar 2020 13:54:58 -0500
Subject: [PATCH] [libc++] Revert to previous implementation of __has_rebind

The new implementation introduced in 5b1e5b43 broke the bot running GCC 5.
---
 libcxx/include/memory | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/libcxx/include/memory b/libcxx/include/memory
index 9d56e81..bea55d6 100644
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -841,12 +841,16 @@ struct __pointer_traits_difference_type<_Ptr, true>
     typedef _LIBCPP_NODEBUG_TYPE typename _Ptr::difference_type type;
 };
 
-template <class _Tp, class _Up, class = void>
-struct __has_rebind : false_type {};
-
 template <class _Tp, class _Up>
-struct __has_rebind<_Tp, _Up,
-    typename __void_t<typename _Tp::template rebind<_Up> >::type> : true_type {};
+struct __has_rebind
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Xp> static __two __test(...);
+    template <class _Xp> static char __test(typename _Xp::template rebind<_Up>* = 0);
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
 
 template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
 struct __pointer_traits_rebind
-- 
2.7.4