From 075dfaf2c3aed15291bcd2f205e905ec94fa4166 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Wed, 3 Feb 2021 01:37:30 -0800
Subject: [PATCH] Perma-workaround DevCom-1328628 "SFINAE bug when a default
 argument is protected".

---
 stl/inc/xutility | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/stl/inc/xutility b/stl/inc/xutility
index 8c223caa7a..eb2a04cadf 100644
--- a/stl/inc/xutility
+++ b/stl/inc/xutility
@@ -131,10 +131,10 @@ _NODISCARD constexpr void* _Voidify_iter(_Iter _It) noexcept {
 
 // FUNCTION TEMPLATE construct_at
 #if _HAS_CXX20
-template <class _Ty, class... _Types>
-_CONSTEXPR20_DYNALLOC auto construct_at(_Ty* const _Location, _Types&&... _Args) noexcept(
-    noexcept(::new (_Voidify_iter(_Location)) _Ty(_STD forward<_Types>(_Args)...))) // strengthened
-    -> decltype(::new (_Voidify_iter(_Location)) _Ty(_STD forward<_Types>(_Args)...)) {
+template <class _Ty, class... _Types,
+    class = void_t<decltype(::new (_STD declval<void*>()) _Ty(_STD declval<_Types>()...))>>
+_CONSTEXPR20_DYNALLOC _Ty* construct_at(_Ty* const _Location, _Types&&... _Args) noexcept(
+    noexcept(::new (_Voidify_iter(_Location)) _Ty(_STD forward<_Types>(_Args)...))) /* strengthened */ {
     return ::new (_Voidify_iter(_Location)) _Ty(_STD forward<_Types>(_Args)...);
 }
 #endif // _HAS_CXX20