supports_ref.patch

diff --git a/include/optional b/include/optional
index 3f67363..438fed2 100644
--- a/include/optional
+++ b/include/optional
@@ -184,13 +184,31 @@ struct nullopt_t
 
 /* inline */ constexpr nullopt_t nullopt{nullopt_t::__secret_tag{}, nullopt_t::__secret_tag{}};
 
+template <class _Tp, bool = is_trivially_copyable<_Tp>::value>
+struct __optional_value {
+  __optional_value(__optional_value const&) = delete;
+  __optional_value& operator=(__optional_value const&) = delete;
+  template <class ..._Args>
+  constexpr __optional_value(_Args&&... __args) : __value_(_VSTD::forward<_Args>(__args)...) {}
+  _Tp __value_;
+};
+
+template <class _Tp>
+struct __optional_value<_Tp, true> {
+  static_assert(!is_reference<_Tp>::value, "");
+  template <class ..._Args>
+  constexpr __optional_value(_Args&&... __args) : __value_(_VSTD::forward<_Args>(__args)...) {}
+  _Tp __value_;
+};
+
 template <class _Tp, bool = is_trivially_destructible_v<_Tp>>
 struct __optional_destruct_base;
 
 template <class _Tp>
 struct __optional_destruct_base<_Tp, false>
 {
-    typedef _Tp value_type;
+    static_assert(!is_reference<_Tp>::value, "");
+    using value_type = __optional_value<_Tp>;
     union
     {
         char __null_state_;
@@ -230,7 +248,7 @@ struct __optional_destruct_base<_Tp, false>
 template <class _Tp>
 struct __optional_destruct_base<_Tp, true>
 {
-    typedef _Tp value_type;
+    typedef __optional_value<_Tp> value_type;
     union
     {
         char __null_state_;
@@ -263,7 +281,7 @@ template <class _Tp>
 struct __optional_storage_base : __optional_destruct_base<_Tp>
 {
     using __base = __optional_destruct_base<_Tp>;
-    using typename __base::value_type;
+    using value_type = _Tp;
     using __base::__base;
 
     _LIBCPP_INLINE_VISIBILITY
@@ -275,22 +293,22 @@ struct __optional_storage_base : __optional_destruct_base<_Tp>
     _LIBCPP_INLINE_VISIBILITY
     constexpr value_type& __get() & noexcept
     {
-        return this->__val_;
+        return this->__val_.__value_;
     }
     _LIBCPP_INLINE_VISIBILITY
     constexpr const value_type& __get() const& noexcept
     {
-        return this->__val_;
+        return this->__val_.__value_;
     }
     _LIBCPP_INLINE_VISIBILITY
     constexpr value_type&& __get() && noexcept
     {
-        return _VSTD::move(this->__val_);
+        return _VSTD::move(this->__val_.__value_);
     }
     _LIBCPP_INLINE_VISIBILITY
     constexpr const value_type&& __get() const&& noexcept
     {
-        return _VSTD::move(this->__val_);
+        return _VSTD::move(this->__val_.__value_);
     }
 
     template <class... _Args>
@@ -298,7 +316,8 @@ struct __optional_storage_base : __optional_destruct_base<_Tp>
     void __construct(_Args&&... __args)
     {
         _LIBCPP_ASSERT(!has_value(), "__construct called for engaged __optional_storage");
-        ::new(_VSTD::addressof(this->__val_)) value_type(_VSTD::forward<_Args>(__args)...);
+        ::new(_VSTD::addressof(this->__val_)) __optional_value<_Tp>(
+            _VSTD::forward<_Args>(__args)...);
         this->__engaged_ = true;
     }
 
@@ -317,7 +336,7 @@ struct __optional_storage_base : __optional_destruct_base<_Tp>
         if (this->__engaged_ == __opt.has_value())
         {
             if (this->__engaged_)
-                this->__val_ = _VSTD::forward<_That>(__opt).__get();
+                this->__val_.__value_ = _VSTD::forward<_That>(__opt).__get();
         }
         else
         {
@@ -405,8 +424,6 @@ public:
     using __base = __optional_storage<_Tp>;
     using typename __base::value_type;
 
-    static_assert(!is_reference_v<value_type>,
-        "Instantiation of optional with a reference type is ill-formed.");
     static_assert(!is_same_v<remove_cv_t<value_type>, nullopt_t>,
         "Instantiation of optional with a nullopt_t type is ill-formed.");
     static_assert(is_reference_v<value_type> || is_object_v<value_type>,
@@ -607,9 +624,11 @@ public:
         }
     }
 
+    using __raw_value_type = remove_reference_t<value_type>;
+
     _LIBCPP_INLINE_VISIBILITY
     constexpr
-    value_type const*
+    __raw_value_type const*
     operator->() const
     {
         _LIBCPP_ASSERT(this->has_value(), "optional operator-> called for disengaged value");
@@ -622,7 +641,7 @@ public:
 
     _LIBCPP_INLINE_VISIBILITY
     constexpr
-    value_type*
+    __raw_value_type*
     operator->()
     {
         _LIBCPP_ASSERT(this->has_value(), "optional operator-> called for disengaged value");
@@ -735,14 +754,14 @@ public:
 
 private:
     _LIBCPP_INLINE_VISIBILITY
-    _Tp const*
+    __raw_value_type const*
     __operator_arrow(true_type) const
     {
         return _VSTD::addressof(this->__get());
     }
 
     _LIBCPP_INLINE_VISIBILITY
-    constexpr _Tp const*
+    constexpr __raw_value_type const*
     __operator_arrow(false_type) const
     {
         return &this->__get();