diff --git a/stl/inc/mdspan b/stl/inc/mdspan
index e06ca1a4d2b..18bfbd32420 100644
--- a/stl/inc/mdspan
+++ b/stl/inc/mdspan
@@ -304,7 +304,7 @@ public:
         }
     }
 
-    template <class... _IndexTypes, size_t... _Seq>
+    template <size_t... _Seq, class... _IndexTypes>
     _NODISCARD constexpr bool _Contains_multidimensional_index(
         index_sequence<_Seq...>, _IndexTypes... _Indices) const noexcept {
         _STL_INTERNAL_STATIC_ASSERT((same_as<_IndexTypes, index_type> && ...));
@@ -321,7 +321,7 @@ inline constexpr size_t _Repeat_dynamic_extent = dynamic_extent;
 
 template <class... _Integrals>
     requires (is_convertible_v<_Integrals, size_t> && ...)
-extents(_Integrals...) -> extents<size_t, _Repeat_dynamic_extent<_Integrals>...>;
+explicit extents(_Integrals...) -> extents<size_t, _Repeat_dynamic_extent<_Integrals>...>;
 
 template <class _IndexType, class _Indices>
 struct _Dextents_impl;
@@ -532,7 +532,7 @@ public:
     template <class _OtherExtents>
         requires is_constructible_v<extents_type, _OtherExtents>
     constexpr explicit(extents_type::rank() > 0)
-        mapping(const layout_stride::template mapping<_OtherExtents>& _Other) noexcept // strengthened
+        mapping(const layout_stride::mapping<_OtherExtents>& _Other) noexcept // strengthened
         : _Base(_Other.extents()) {
 #if _CONTAINER_DEBUG_LEVEL > 0
         if constexpr (extents_type::rank() > 0) {
@@ -684,8 +684,7 @@ public:
 
     template <class _OtherExtents>
         requires is_constructible_v<extents_type, _OtherExtents>
-    constexpr explicit(extents_type::rank() > 0)
-        mapping(const layout_stride::template mapping<_OtherExtents>& _Other) noexcept
+    constexpr explicit(extents_type::rank() > 0) mapping(const layout_stride::mapping<_OtherExtents>& _Other) noexcept
         : _Base(_Other.extents()) {
 #if _CONTAINER_DEBUG_LEVEL > 0
         if constexpr (extents_type::rank() > 0) {
@@ -1045,13 +1044,13 @@ struct default_accessor {
         requires is_convertible_v<_OtherElementType (*)[], element_type (*)[]>
     constexpr default_accessor(default_accessor<_OtherElementType>) noexcept {}
 
-    _NODISCARD constexpr data_handle_type offset(data_handle_type _Ptr, size_t _Idx) const noexcept {
-        return _Ptr + _Idx;
-    }
-
     _NODISCARD constexpr reference access(data_handle_type _Ptr, size_t _Idx) const noexcept {
         return _Ptr[_Idx];
     }
+
+    _NODISCARD constexpr data_handle_type offset(data_handle_type _Ptr, size_t _Idx) const noexcept {
+        return _Ptr + _Idx;
+    }
 };
 
 template <class _LayoutPolicy, class _Extents>
@@ -1200,7 +1199,7 @@ public:
           _Ptr(_STD move(_Ptr_)) {}
 
     template <class _OtherIndexType, size_t _Size>
-        requires is_convertible_v<_OtherIndexType, index_type>
+        requires is_convertible_v<const _OtherIndexType&, index_type>
                   && is_nothrow_constructible_v<index_type, const _OtherIndexType&>
                   && (_Size == rank() || _Size == rank_dynamic())
                   && is_constructible_v<mapping_type, extents_type> && is_default_constructible_v<accessor_type>
@@ -1277,32 +1276,45 @@ public:
         noexcept(noexcept(_Access_impl(static_cast<index_type>(_STD move(_Indices))...))) /* strengthened */ {
         return _Access_impl(static_cast<index_type>(_STD move(_Indices))...);
     }
-#endif // __cpp_multidimensional_subscript
 
+private:
+    template <class _OtherIndexType, size_t... _Seq>
+    _NODISCARD constexpr reference _Multidimensional_subscript(span<_OtherIndexType, rank()> _Indices,
+        index_sequence<_Seq...>) const noexcept(noexcept(operator[](_STD as_const(_Indices[_Seq])...))) {
+        return operator[](_STD as_const(_Indices[_Seq])...);
+    }
+#else // ^^^ defined(__cpp_multidimensional_subscript) / !defined(__cpp_multidimensional_subscript) vvv
+private:
+    template <class... _OtherIndexTypes>
+    _NODISCARD constexpr reference _Multidimensional_access(_OtherIndexTypes... _Indices) const
+        noexcept(noexcept(_Access_impl(static_cast<index_type>(_STD move(_Indices))...))) {
+        return _Access_impl(static_cast<index_type>(_STD move(_Indices))...);
+    }
+
+    template <class _OtherIndexType, size_t... _Seq>
+    _NODISCARD constexpr reference _Multidimensional_subscript(span<_OtherIndexType, rank()> _Indices,
+        index_sequence<_Seq...>) const noexcept(noexcept(_Multidimensional_access(_STD as_const(_Indices[_Seq])...))) {
+        return _Multidimensional_access(_STD as_const(_Indices[_Seq])...);
+    }
+#endif // ^^^ !defined(__cpp_multidimensional_subscript) ^^^
+
+public:
     template <class _OtherIndexType>
         requires is_convertible_v<const _OtherIndexType&, index_type>
               && is_nothrow_constructible_v<index_type, const _OtherIndexType&>
-    _NODISCARD constexpr reference operator[](span<_OtherIndexType, rank()> _Indices) const {
-        return [&]<size_t... _Seq>(index_sequence<_Seq...>) -> reference {
-#ifdef __cpp_multidimensional_subscript // TRANSITION, P2128R6
-            return operator[](_STD as_const(_Indices[_Seq])...);
-#else // ^^^ defined(__cpp_multidimensional_subscript) / !defined(__cpp_multidimensional_subscript) vvv
-            return _Multidimensional_access(_STD as_const(_Indices[_Seq])...);
-#endif // ^^^ !defined(__cpp_multidimensional_subscript) ^^^
-        }(make_index_sequence<rank()>{});
+    _NODISCARD constexpr reference operator[](span<_OtherIndexType, rank()> _Indices) const
+        noexcept(noexcept(_Multidimensional_subscript(_Indices, make_index_sequence<rank()>{}))) /* strengthened */
+    {
+        return _Multidimensional_subscript(_Indices, make_index_sequence<rank()>{});
     }
 
     template <class _OtherIndexType>
         requires is_convertible_v<const _OtherIndexType&, index_type>
               && is_nothrow_constructible_v<index_type, const _OtherIndexType&>
-    _NODISCARD constexpr reference operator[](const array<_OtherIndexType, rank()>& _Indices) const {
-        return [&]<size_t... _Seq>(index_sequence<_Seq...>) -> reference {
-#ifdef __cpp_multidimensional_subscript // TRANSITION, P2128R6
-            return operator[](_Indices[_Seq]...);
-#else // ^^^ defined(__cpp_multidimensional_subscript) / !defined(__cpp_multidimensional_subscript) vvv
-            return _Multidimensional_access(_Indices[_Seq]...);
-#endif // ^^^ !defined(__cpp_multidimensional_subscript) ^^^
-        }(make_index_sequence<rank()>{});
+    _NODISCARD constexpr reference operator[](const array<_OtherIndexType, rank()>& _Indices) const noexcept(
+        noexcept(_Multidimensional_subscript(span{_Indices}, make_index_sequence<rank()>{}))) /* strengthened */
+    {
+        return _Multidimensional_subscript(span{_Indices}, make_index_sequence<rank()>{});
     }
 
     _NODISCARD constexpr size_type size() const noexcept {
@@ -1359,19 +1371,19 @@ public:
         return this->_Acc;
     }
 
-    _NODISCARD static constexpr bool is_always_unique() noexcept(
-        noexcept(mapping_type::is_always_unique())) /* strengthened */ {
-        return mapping_type::is_always_unique();
+    _NODISCARD static constexpr bool is_always_unique() noexcept /* strengthened */ {
+        constexpr bool _Result = mapping_type::is_always_unique();
+        return _Result;
     }
 
-    _NODISCARD static constexpr bool is_always_exhaustive() noexcept(
-        noexcept(mapping_type::is_always_exhaustive())) /* strengthened */ {
-        return mapping_type::is_always_exhaustive();
+    _NODISCARD static constexpr bool is_always_exhaustive() noexcept /* strengthened */ {
+        constexpr bool _Result = mapping_type::is_always_exhaustive();
+        return _Result;
     }
 
-    _NODISCARD static constexpr bool is_always_strided() noexcept(
-        noexcept(mapping_type::is_always_strided())) /* strengthened */ {
-        return mapping_type::is_always_strided();
+    _NODISCARD static constexpr bool is_always_strided() noexcept /* strengthened */ {
+        constexpr bool _Result = mapping_type::is_always_strided();
+        return _Result;
     }
 
     _NODISCARD constexpr bool is_unique() const noexcept(noexcept(this->_Map.is_unique())) /* strengthened */ {
@@ -1392,16 +1404,9 @@ public:
     }
 
 private:
-#ifndef __cpp_multidimensional_subscript // TRANSITION, P2128R6
-    template <class... _OtherIndexTypes>
-    _NODISCARD constexpr reference _Multidimensional_access(_OtherIndexTypes... _Indices) const {
-        return _Access_impl(static_cast<index_type>(_STD move(_Indices))...);
-    }
-#endif // ^^^ !defined(__cpp_multidimensional_subscript) ^^^
-
     template <class... _OtherIndexTypes>
     _NODISCARD constexpr reference _Access_impl(_OtherIndexTypes... _Indices) const
-        noexcept(noexcept(this->_Acc.access(_Ptr, static_cast<size_t>(this->_Map(_Indices...))))) /* strengthened */ {
+        noexcept(noexcept(this->_Acc.access(_Ptr, static_cast<size_t>(this->_Map(_Indices...))))) {
         _STL_INTERNAL_STATIC_ASSERT((same_as<_OtherIndexTypes, index_type> && ...));
 #if _CONTAINER_DEBUG_LEVEL > 0
         _STL_VERIFY(this->_Map.extents()._Contains_multidimensional_index(make_index_sequence<rank()>{}, _Indices...),