Merge branch 'master' into gfortran-testdevel/gfortran-test

14 files changed, 309 insertions, 123 deletions

diff --git a/libstdc++-v3/include/bits/align.h b/libstdc++-v3/include/bits/align.h
index 2b40c37..6a85244 100644
--- a/libstdc++-v3/include/bits/align.h
+++ b/libstdc++-v3/include/bits/align.h
@@ -102,6 +102,23 @@ align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
     }
 #endif // __glibcxx_assume_aligned
 
+#ifdef __glibcxx_is_sufficiently_aligned // C++ >= 26
+  /** @brief Is `__ptr` aligned to an _Align byte boundary?
+   *
+   *  @tparam _Align An alignment value
+   *  @tparam _Tp    An object type
+   *
+   *  C++26 20.2.5 [ptr.align]
+   *
+   *  @ingroup memory
+   */
+  template<size_t _Align, class _Tp>
+    [[nodiscard,__gnu__::__always_inline__]]
+    inline bool
+    is_sufficiently_aligned(_Tp* __ptr)
+    { return reinterpret_cast<__UINTPTR_TYPE__>(__ptr) % _Align == 0; }
+#endif // __glibcxx_is_sufficiently_aligned
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
 
diff --git a/libstdc++-v3/include/bits/funcwrap.h b/libstdc++-v3/include/bits/funcwrap.h
index 9db4ab7..70ecfd9 100644
--- a/libstdc++-v3/include/bits/funcwrap.h
+++ b/libstdc++-v3/include/bits/funcwrap.h
@@ -419,6 +419,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        _M_manage = _Manager::_S_empty;
      }
 
+     void _M_destroy() noexcept
+     { _M_manage(_Manager::_Op::_Destroy, _M_storage, nullptr); }
+
      ~_Mo_base()
      { _M_destroy(); }
 
@@ -434,17 +437,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        std::swap(_M_manage, __x._M_manage);
      }
 
-     _Storage _M_storage;
-
-   private:
-     void _M_destroy() noexcept
-     { _M_manage(_Manager::_Op::_Destroy, _M_storage, nullptr); }
-
      _Manager::_Func _M_manage;
-
-#ifdef __glibcxx_copyable_function // C++ >= 26 && HOSTED
-     friend class _Cpy_base;
-#endif // __glibcxx_copyable_function
+     _Storage _M_storage;
    };
 #endif // __glibcxx_copyable_function || __glibcxx_copyable_function
 } // namespace __polyfunc
diff --git a/libstdc++-v3/include/bits/indirect.h b/libstdc++-v3/include/bits/indirect.h
index e8000d7..89fa8c8 100644
--- a/libstdc++-v3/include/bits/indirect.h
+++ b/libstdc++-v3/include/bits/indirect.h
@@ -286,8 +286,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       constexpr auto&&
       operator*(this _Self&& __self) noexcept
       {
-	__glibcxx_assert(__self._M_objp != nullptr);
-	return std::forward_like<_Self>(*((_Self)__self)._M_objp);
+	// n.b. [allocator.requirements.general] p22 implies
+	// dereferencing const pointer is same as pointer
+	const indirect& __iself = (const indirect&)__self;
+	__glibcxx_assert(__iself._M_objp != nullptr);
+	return std::forward_like<_Self>(*__iself._M_objp);
       }
 
       constexpr const_pointer
diff --git a/libstdc++-v3/include/bits/move.h b/libstdc++-v3/include/bits/move.h
index 061e6b4..8c4f461 100644
--- a/libstdc++-v3/include/bits/move.h
+++ b/libstdc++-v3/include/bits/move.h
@@ -89,7 +89,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return static_cast<_Tp&&>(__t);
     }
 
-#if __glibcxx_forward_like // C++ >= 23
   template<typename _Tp, typename _Up>
   struct __like_impl; // _Tp must be a reference and _Up an lvalue reference
 
@@ -112,6 +111,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Tp, typename _Up>
     using __like_t = typename __like_impl<_Tp&&, _Up&>::type;
 
+#if __glibcxx_forward_like // C++ >= 23
   /** @brief Forward with the cv-qualifiers and value category of another type.
    *  @tparam _Tp An lvalue reference or rvalue reference.
    *  @tparam _Up An lvalue reference type deduced from the function argument.
diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h
index 9f8945a..6e1e06c 100644
--- a/libstdc++-v3/include/bits/ranges_algo.h
+++ b/libstdc++-v3/include/bits/ranges_algo.h
@@ -109,7 +109,7 @@ namespace ranges
     template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
 	     typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred, _Proj __proj = {}) const
       {
@@ -122,7 +122,7 @@ namespace ranges
     template<input_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>>
 	       _Pred>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -137,7 +137,7 @@ namespace ranges
     template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
 	     typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred, _Proj __proj = {}) const
       {
@@ -150,7 +150,7 @@ namespace ranges
     template<input_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>>
 	       _Pred>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -165,7 +165,7 @@ namespace ranges
     template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
 	     typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred, _Proj __proj = {}) const
       {
@@ -178,7 +178,7 @@ namespace ranges
     template<input_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>>
 	       _Pred>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -279,7 +279,7 @@ namespace ranges
 	     typename _Pred = ranges::equal_to,
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
-      constexpr _Iter1
+      [[nodiscard]] constexpr _Iter1
       operator()(_Iter1 __first1, _Sent1 __last1,
 		 _Iter2 __first2, _Sent2 __last2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
@@ -298,7 +298,7 @@ namespace ranges
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
 				     _Pred, _Proj1, _Proj2>
-      constexpr borrowed_iterator_t<_Range1>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range1>
       operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
       {
@@ -319,7 +319,7 @@ namespace ranges
       requires indirect_binary_predicate<ranges::equal_to,
 					 projected<_Iter, _Proj>,
 					 const _Tp*>
-      constexpr iter_difference_t<_Iter>
+      [[nodiscard]] constexpr iter_difference_t<_Iter>
       operator()(_Iter __first, _Sent __last,
 		 const _Tp& __value, _Proj __proj = {}) const
       {
@@ -336,7 +336,7 @@ namespace ranges
       requires indirect_binary_predicate<ranges::equal_to,
 					 projected<iterator_t<_Range>, _Proj>,
 					 const _Tp*>
-      constexpr range_difference_t<_Range>
+      [[nodiscard]] constexpr range_difference_t<_Range>
       operator()(_Range&& __r, const _Tp& __value, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -726,7 +726,7 @@ namespace ranges
 	     typename _Pred = ranges::equal_to,
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
-      constexpr subrange<_Iter1>
+      [[nodiscard]] constexpr subrange<_Iter1>
       operator()(_Iter1 __first1, _Sent1 __last1,
 		 _Iter2 __first2, _Sent2 __last2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
@@ -783,7 +783,7 @@ namespace ranges
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
 				     _Pred, _Proj1, _Proj2>
-      constexpr borrowed_subrange_t<_Range1>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range1>
       operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
       {
@@ -806,7 +806,7 @@ namespace ranges
 	     indirect_equivalence_relation<projected<_Iter1, _Proj1>,
 					   projected<_Iter2, _Proj2>> _Pred
 	       = ranges::equal_to>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter1 __first1, _Sent1 __last1,
 		 _Iter2 __first2, _Sent2 __last2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
@@ -875,7 +875,7 @@ namespace ranges
 	     indirect_equivalence_relation<
 	       projected<iterator_t<_Range1>, _Proj1>,
 	       projected<iterator_t<_Range2>, _Proj2>> _Pred = ranges::equal_to>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
       {
@@ -1281,7 +1281,7 @@ namespace ranges
     template<permutable _Iter, sentinel_for<_Iter> _Sent,
 	     typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr subrange<_Iter>
+      [[nodiscard]] constexpr subrange<_Iter>
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred, _Proj __proj = {}) const
       {
@@ -1305,7 +1305,7 @@ namespace ranges
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>>
 	       _Pred>
       requires permutable<iterator_t<_Range>>
-      constexpr borrowed_subrange_t<_Range>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range>
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -1323,7 +1323,7 @@ namespace ranges
       requires indirect_binary_predicate<ranges::equal_to,
 					 projected<_Iter, _Proj>,
 					 const _Tp*>
-      constexpr subrange<_Iter>
+      [[nodiscard]] constexpr subrange<_Iter>
       operator()(_Iter __first, _Sent __last,
 		 const _Tp& __value, _Proj __proj = {}) const
       {
@@ -1341,7 +1341,7 @@ namespace ranges
 	&& indirect_binary_predicate<ranges::equal_to,
 				     projected<iterator_t<_Range>, _Proj>,
 				     const _Tp*>
-      constexpr borrowed_subrange_t<_Range>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range>
       operator()(_Range&& __r, const _Tp& __value, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -1440,7 +1440,7 @@ namespace ranges
 	     typename _Proj = identity,
 	     indirect_equivalence_relation<
 	       projected<_Iter, _Proj>> _Comp = ranges::equal_to>
-      constexpr subrange<_Iter>
+      [[nodiscard]] constexpr subrange<_Iter>
       operator()(_Iter __first, _Sent __last,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -1462,7 +1462,7 @@ namespace ranges
 	     indirect_equivalence_relation<
 	       projected<iterator_t<_Range>, _Proj>> _Comp = ranges::equal_to>
       requires permutable<iterator_t<_Range>>
-      constexpr borrowed_subrange_t<_Range>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range>
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -2849,7 +2849,7 @@ namespace ranges
 	     typename _Proj = identity,
 	     indirect_strict_weak_order<projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -2868,7 +2868,7 @@ namespace ranges
     template<forward_range _Range, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -2884,7 +2884,7 @@ namespace ranges
 	     typename _Proj = identity,
 	     indirect_strict_weak_order<projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter __first, _Sent __last,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -2903,7 +2903,7 @@ namespace ranges
     template<forward_range _Range, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -2987,7 +2987,7 @@ namespace ranges
 	     typename _Tp _GLIBCXX26_RANGE_ALGO_DEF_VAL_T(_Iter, _Proj),
 	     indirect_strict_weak_order<const _Tp*, projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 const _Tp& __value, _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -3017,7 +3017,7 @@ namespace ranges
 	     indirect_strict_weak_order<const _Tp*,
 					projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r,
 		 const _Tp& __value, _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -3035,7 +3035,7 @@ namespace ranges
 	     typename _Tp _GLIBCXX26_RANGE_ALGO_DEF_VAL_T(_Iter, _Proj),
 	     indirect_strict_weak_order<const _Tp*, projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 const _Tp& __value, _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -3065,7 +3065,7 @@ namespace ranges
 	     indirect_strict_weak_order<const _Tp*,
 					projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r,
 		 const _Tp& __value, _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -3083,7 +3083,7 @@ namespace ranges
 	     typename _Tp _GLIBCXX26_RANGE_ALGO_DEF_VAL_T(_Iter, _Proj),
 	     indirect_strict_weak_order<const _Tp*, projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr subrange<_Iter>
+      [[nodiscard]] constexpr subrange<_Iter>
       operator()(_Iter __first, _Sent __last,
 		 const _Tp& __value, _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -3128,7 +3128,7 @@ namespace ranges
 	     indirect_strict_weak_order<const _Tp*,
 					projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr borrowed_subrange_t<_Range>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range>
       operator()(_Range&& __r, const _Tp& __value,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -3146,7 +3146,7 @@ namespace ranges
 	     typename _Tp _GLIBCXX26_RANGE_ALGO_DEF_VAL_T(_Iter, _Proj),
 	     indirect_strict_weak_order<const _Tp*, projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter __first, _Sent __last,
 		 const _Tp& __value, _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -3164,7 +3164,7 @@ namespace ranges
 	     indirect_strict_weak_order<const _Tp*,
 					projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range&& __r, const _Tp& __value, _Comp __comp = {},
 		 _Proj __proj = {}) const
       {
@@ -3180,7 +3180,7 @@ namespace ranges
     template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
 	     typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred, _Proj __proj = {}) const
       {
@@ -3196,7 +3196,7 @@ namespace ranges
     template<input_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>>
 	       _Pred>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -3488,7 +3488,7 @@ namespace ranges
     template<forward_iterator _Iter, sentinel_for<_Iter> _Sent,
 	     typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred, _Proj __proj = {}) const
       {
@@ -3514,7 +3514,7 @@ namespace ranges
     template<forward_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>>
 	       _Pred>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -3875,7 +3875,7 @@ namespace ranges
 	     indirect_strict_weak_order<projected<_Iter1, _Proj1>,
 					projected<_Iter2, _Proj2>>
 	       _Comp = ranges::less>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter1 __first1, _Sent1 __last1,
 		 _Iter2 __first2, _Sent2 __last2,
 		 _Comp __comp = {},
@@ -3904,7 +3904,7 @@ namespace ranges
 	     indirect_strict_weak_order<projected<iterator_t<_Range1>, _Proj1>,
 					projected<iterator_t<_Range2>, _Proj2>>
 	       _Comp = ranges::less>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range1&& __r1, _Range2&& __r2, _Comp __comp = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
       {
@@ -4175,7 +4175,7 @@ namespace ranges
     template<typename _Tp, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<const _Tp*, _Proj>>
 	       _Comp = ranges::less>
-      constexpr const _Tp&
+      [[nodiscard]] constexpr const _Tp&
       operator()(const _Tp& __a, const _Tp& __b,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -4192,7 +4192,7 @@ namespace ranges
 	       _Comp = ranges::less>
       requires indirectly_copyable_storable<iterator_t<_Range>,
 					    range_value_t<_Range>*>
-      constexpr range_value_t<_Range>
+      [[nodiscard]] constexpr range_value_t<_Range>
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	auto __first = ranges::begin(__r);
@@ -4213,7 +4213,7 @@ namespace ranges
     template<copyable _Tp, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<const _Tp*, _Proj>>
 	       _Comp = ranges::less>
-      constexpr _Tp
+      [[nodiscard]] constexpr _Tp
       operator()(initializer_list<_Tp> __r,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -4229,7 +4229,7 @@ namespace ranges
     template<typename _Tp, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp
 	       = ranges::less>
-      constexpr const _Tp&
+      [[nodiscard]] constexpr const _Tp&
       operator()(const _Tp& __val, const _Tp& __lo, const _Tp& __hi,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -4279,7 +4279,7 @@ namespace ranges
     template<typename _Tp, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<const _Tp*, _Proj>>
 	       _Comp = ranges::less>
-      constexpr minmax_result<const _Tp&>
+      [[nodiscard]] constexpr minmax_result<const _Tp&>
       operator()(const _Tp& __a, const _Tp& __b,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -4295,7 +4295,7 @@ namespace ranges
 	     indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
       requires indirectly_copyable_storable<iterator_t<_Range>, range_value_t<_Range>*>
-      constexpr minmax_result<range_value_t<_Range>>
+      [[nodiscard]] constexpr minmax_result<range_value_t<_Range>>
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	auto __first = ranges::begin(__r);
@@ -4354,7 +4354,7 @@ namespace ranges
     template<copyable _Tp, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<const _Tp*, _Proj>>
 	       _Comp = ranges::less>
-      constexpr minmax_result<_Tp>
+      [[nodiscard]] constexpr minmax_result<_Tp>
       operator()(initializer_list<_Tp> __r,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -4371,7 +4371,7 @@ namespace ranges
 	     typename _Proj = identity,
 	     indirect_strict_weak_order<projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -4392,7 +4392,7 @@ namespace ranges
     template<forward_range _Range, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -4408,7 +4408,7 @@ namespace ranges
 	     typename _Proj = identity,
 	     indirect_strict_weak_order<projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -4429,7 +4429,7 @@ namespace ranges
     template<forward_range _Range, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -4448,7 +4448,7 @@ namespace ranges
 	     typename _Proj = identity,
 	     indirect_strict_weak_order<projected<_Iter, _Proj>>
 	       _Comp = ranges::less>
-      constexpr minmax_element_result<_Iter>
+      [[nodiscard]] constexpr minmax_element_result<_Iter>
       operator()(_Iter __first, _Sent __last,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -4503,7 +4503,7 @@ namespace ranges
     template<forward_range _Range, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>>
 	       _Comp = ranges::less>
-      constexpr minmax_element_result<borrowed_iterator_t<_Range>>
+      [[nodiscard]] constexpr minmax_element_result<borrowed_iterator_t<_Range>>
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -4521,7 +4521,7 @@ namespace ranges
 	     indirect_strict_weak_order<projected<_Iter1, _Proj1>,
 					projected<_Iter2, _Proj2>>
 	       _Comp = ranges::less>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter1 __first1, _Sent1 __last1,
 		 _Iter2 __first2, _Sent2 __last2,
 		 _Comp __comp = {},
@@ -4607,7 +4607,7 @@ namespace ranges
 	     indirect_strict_weak_order<projected<iterator_t<_Range1>, _Proj1>,
 					projected<iterator_t<_Range2>, _Proj2>>
 	       _Comp = ranges::less>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range1&& __r1, _Range2&& __r2, _Comp __comp = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
       {
@@ -4836,7 +4836,7 @@ namespace ranges
 	     typename _Proj = identity,
 	     typename _Tp _GLIBCXX26_RANGE_ALGO_DEF_VAL_T(_Iter, _Proj)>
       requires indirect_binary_predicate<ranges::equal_to, projected<_Iter, _Proj>, const _Tp*>
-      constexpr subrange<_Iter>
+      [[nodiscard]] constexpr subrange<_Iter>
       operator()(_Iter __first, _Sent __last, const _Tp& __value, _Proj __proj = {}) const
       {
 	if constexpr (same_as<_Iter, _Sent> && bidirectional_iterator<_Iter>)
@@ -4869,7 +4869,7 @@ namespace ranges
 	     typename _Tp
 	       _GLIBCXX26_RANGE_ALGO_DEF_VAL_T(iterator_t<_Range>, _Proj)>
       requires indirect_binary_predicate<ranges::equal_to, projected<iterator_t<_Range>, _Proj>, const _Tp*>
-      constexpr borrowed_subrange_t<_Range>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range>
       operator()(_Range&& __r, const _Tp& __value, _Proj __proj = {}) const
       { return (*this)(ranges::begin(__r), ranges::end(__r), __value, std::move(__proj)); }
   };
@@ -4880,7 +4880,7 @@ namespace ranges
   {
     template<forward_iterator _Iter, sentinel_for<_Iter> _Sent, typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr subrange<_Iter>
+      [[nodiscard]] constexpr subrange<_Iter>
       operator()(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {}) const
       {
 	if constexpr (same_as<_Iter, _Sent> && bidirectional_iterator<_Iter>)
@@ -4911,7 +4911,7 @@ namespace ranges
 
     template<forward_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Pred>
-      constexpr borrowed_subrange_t<_Range>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range>
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       { return (*this)(ranges::begin(__r), ranges::end(__r), std::move(__pred), std::move(__proj)); }
   };
@@ -4922,7 +4922,7 @@ namespace ranges
   {
     template<forward_iterator _Iter, sentinel_for<_Iter> _Sent, typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr subrange<_Iter>
+      [[nodiscard]] constexpr subrange<_Iter>
       operator()(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {}) const
       {
 	if constexpr (same_as<_Iter, _Sent> && bidirectional_iterator<_Iter>)
@@ -4953,7 +4953,7 @@ namespace ranges
 
     template<forward_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Pred>
-      constexpr borrowed_subrange_t<_Range>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range>
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       { return (*this)(ranges::begin(__r), ranges::end(__r), std::move(__pred), std::move(__proj)); }
   };
diff --git a/libstdc++-v3/include/bits/ranges_algobase.h b/libstdc++-v3/include/bits/ranges_algobase.h
index a08f659b..45ed5b4 100644
--- a/libstdc++-v3/include/bits/ranges_algobase.h
+++ b/libstdc++-v3/include/bits/ranges_algobase.h
@@ -101,7 +101,7 @@ namespace ranges
 	     typename _Pred = ranges::equal_to,
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Iter1 __first1, _Sent1 __last1,
 		 _Iter2 __first2, _Sent2 __last2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
@@ -168,7 +168,7 @@ namespace ranges
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
 				     _Pred, _Proj1, _Proj2>
-      constexpr bool
+      [[nodiscard]] constexpr bool
       operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
       {
diff --git a/libstdc++-v3/include/bits/ranges_util.h b/libstdc++-v3/include/bits/ranges_util.h
index 53b7f5c..84de258 100644
--- a/libstdc++-v3/include/bits/ranges_util.h
+++ b/libstdc++-v3/include/bits/ranges_util.h
@@ -501,7 +501,7 @@ namespace ranges
 	     typename _Tp _GLIBCXX26_RANGE_ALGO_DEF_VAL_T(_Iter, _Proj)>
       requires indirect_binary_predicate<ranges::equal_to,
 					 projected<_Iter, _Proj>, const _Tp*>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 const _Tp& __value, _Proj __proj = {}) const
       {
@@ -537,7 +537,7 @@ namespace ranges
       requires indirect_binary_predicate<ranges::equal_to,
 					 projected<iterator_t<_Range>, _Proj>,
 					 const _Tp*>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r, const _Tp& __value, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -552,7 +552,7 @@ namespace ranges
     template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
 	     typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred, _Proj __proj = {}) const
       {
@@ -565,7 +565,7 @@ namespace ranges
     template<input_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>>
 	       _Pred>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -580,7 +580,7 @@ namespace ranges
     template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
 	     typename _Proj = identity,
 	     indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred, _Proj __proj = {}) const
       {
@@ -593,7 +593,7 @@ namespace ranges
     template<input_range _Range, typename _Proj = identity,
 	     indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>>
 	       _Pred>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r, _Pred __pred, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
@@ -634,7 +634,7 @@ namespace ranges
 	     typename _Pred = ranges::equal_to,
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
-      constexpr mismatch_result<_Iter1, _Iter2>
+      [[nodiscard]] constexpr mismatch_result<_Iter1, _Iter2>
       operator()(_Iter1 __first1, _Sent1 __last1,
 		 _Iter2 __first2, _Sent2 __last2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
@@ -655,6 +655,7 @@ namespace ranges
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
 				     _Pred, _Proj1, _Proj2>
+      [[nodiscard]]    
       constexpr mismatch_result<iterator_t<_Range1>, iterator_t<_Range2>>
       operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
@@ -675,7 +676,7 @@ namespace ranges
 	     typename _Pred = ranges::equal_to,
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
-      constexpr subrange<_Iter1>
+      [[nodiscard]] constexpr subrange<_Iter1>
       operator()(_Iter1 __first1, _Sent1 __last1,
 		 _Iter2 __first2, _Sent2 __last2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
@@ -719,7 +720,7 @@ namespace ranges
 	     typename _Proj1 = identity, typename _Proj2 = identity>
       requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
 				     _Pred, _Proj1, _Proj2>
-      constexpr borrowed_subrange_t<_Range1>
+      [[nodiscard]] constexpr borrowed_subrange_t<_Range1>
       operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
 		 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
       {
@@ -737,7 +738,7 @@ namespace ranges
     template<typename _Tp, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<const _Tp*, _Proj>>
 	       _Comp = ranges::less>
-      constexpr const _Tp&
+      [[nodiscard]] constexpr const _Tp&
       operator()(const _Tp& __a, const _Tp& __b,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -754,7 +755,7 @@ namespace ranges
 	       _Comp = ranges::less>
       requires indirectly_copyable_storable<iterator_t<_Range>,
 					    range_value_t<_Range>*>
-      constexpr range_value_t<_Range>
+      [[nodiscard]] constexpr range_value_t<_Range>
       operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const
       {
 	auto __first = ranges::begin(__r);
@@ -775,7 +776,7 @@ namespace ranges
     template<copyable _Tp, typename _Proj = identity,
 	     indirect_strict_weak_order<projected<const _Tp*, _Proj>>
 	       _Comp = ranges::less>
-      constexpr _Tp
+      [[nodiscard]] constexpr _Tp
       operator()(initializer_list<_Tp> __r,
 		 _Comp __comp = {}, _Proj __proj = {}) const
       {
@@ -793,7 +794,7 @@ namespace ranges
 	     indirect_binary_predicate<projected<_Iter, _Proj>,
 				       projected<_Iter, _Proj>> _Pred
 	       = ranges::equal_to>
-      constexpr _Iter
+      [[nodiscard]] constexpr _Iter
       operator()(_Iter __first, _Sent __last,
 		 _Pred __pred = {}, _Proj __proj = {}) const
       {
@@ -814,7 +815,7 @@ namespace ranges
 	     indirect_binary_predicate<
 	       projected<iterator_t<_Range>, _Proj>,
 	       projected<iterator_t<_Range>, _Proj>> _Pred = ranges::equal_to>
-      constexpr borrowed_iterator_t<_Range>
+      [[nodiscard]] constexpr borrowed_iterator_t<_Range>
       operator()(_Range&& __r, _Pred __pred = {}, _Proj __proj = {}) const
       {
 	return (*this)(ranges::begin(__r), ranges::end(__r),
diff --git a/libstdc++-v3/include/bits/stl_algo.h b/libstdc++-v3/include/bits/stl_algo.h
index 3f4674d..81a2457 100644
--- a/libstdc++-v3/include/bits/stl_algo.h
+++ b/libstdc++-v3/include/bits/stl_algo.h
@@ -5759,7 +5759,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 #if __cplusplus >= 201103L
   // N2722 + DR 915.
   template<typename _Tp>
-    _GLIBCXX14_CONSTEXPR
+    _GLIBCXX_NODISCARD _GLIBCXX14_CONSTEXPR
     inline _Tp
     min(initializer_list<_Tp> __l)
     {
@@ -5769,7 +5769,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     }
 
   template<typename _Tp, typename _Compare>
-    _GLIBCXX14_CONSTEXPR
+    _GLIBCXX_NODISCARD _GLIBCXX14_CONSTEXPR
     inline _Tp
     min(initializer_list<_Tp> __l, _Compare __comp)
     {
@@ -5779,7 +5779,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     }
 
   template<typename _Tp>
-    _GLIBCXX14_CONSTEXPR
+    _GLIBCXX_NODISCARD _GLIBCXX14_CONSTEXPR
     inline _Tp
     max(initializer_list<_Tp> __l)
     {
@@ -5789,7 +5789,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     }
 
   template<typename _Tp, typename _Compare>
-    _GLIBCXX14_CONSTEXPR
+    _GLIBCXX_NODISCARD _GLIBCXX14_CONSTEXPR
     inline _Tp
     max(initializer_list<_Tp> __l, _Compare __comp)
     {
diff --git a/libstdc++-v3/include/bits/stl_iterator_base_funcs.h b/libstdc++-v3/include/bits/stl_iterator_base_funcs.h
index 637159f..f78e535 100644
--- a/libstdc++-v3/include/bits/stl_iterator_base_funcs.h
+++ b/libstdc++-v3/include/bits/stl_iterator_base_funcs.h
@@ -130,6 +130,28 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     __distance(_OutputIterator, _OutputIterator, output_iterator_tag) = delete;
 #endif
 
+#ifdef __glibcxx_concepts
+namespace __detail
+{
+  // Satisfied if ITER_TRAITS(Iter)::iterator_category is valid and is
+  // at least as strong as ITER_TRAITS(Iter)::iterator_concept.
+  template<typename _Iter>
+    concept __iter_category_converts_to_concept
+      = convertible_to<typename __iter_traits<_Iter>::iterator_category,
+		       typename __iter_traits<_Iter>::iterator_concept>;
+
+  // Satisfied if the type is a C++20 iterator that defines iterator_concept,
+  // and its iterator_concept is stronger than its iterator_category (if any).
+  // Used by std::distance and std::advance to detect iterators which should
+  // dispatch based on their C++20 concept not their C++17 category.
+  template<typename _Iter>
+    concept __promotable_iterator
+      = input_iterator<_Iter>
+	  && requires { typename __iter_traits<_Iter>::iterator_concept; }
+	  && ! __iter_category_converts_to_concept<_Iter>;
+} // namespace __detail
+#endif
+
   /**
    *  @brief A generalization of pointer arithmetic.
    *  @param  __first  An input iterator.
@@ -149,6 +171,24 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     typename iterator_traits<_InputIterator>::difference_type
     distance(_InputIterator __first, _InputIterator __last)
     {
+#ifdef __glibcxx_concepts
+      // A type which satisfies the C++20 random_access_iterator concept might
+      // have input_iterator_tag as its iterator_category type, which would
+      // mean we select the O(n) __distance. Or a C++20 std::input_iterator
+      // that is not a Cpp17InputIterator might have output_iterator_tag as
+      // its iterator_category type and then calling __distance with
+      // std::__iterator_category(__first) would be ill-formed.
+      // So for C++20 iterator types we can just choose to do the right thing.
+      if constexpr (__detail::__promotable_iterator<_InputIterator>)
+	{
+	  if constexpr (random_access_iterator<_InputIterator>)
+	    return __last - __first;
+	  else
+	    return std::__distance(std::move(__first), std::move(__last),
+				   input_iterator_tag());
+	}
+      else // assume it meets the Cpp17InputIterator requirements:
+#endif
       // concept requirements -- taken care of in __distance
       return std::__distance(__first, __last,
 			     std::__iterator_category(__first));
@@ -221,9 +261,31 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     inline _GLIBCXX17_CONSTEXPR void
     advance(_InputIterator& __i, _Distance __n)
     {
-      // concept requirements -- taken care of in __advance
-      typename iterator_traits<_InputIterator>::difference_type __d = __n;
-      std::__advance(__i, __d, std::__iterator_category(__i));
+#ifdef __glibcxx_concepts
+      // A type which satisfies the C++20 bidirectional_iterator concept might
+      // have input_iterator_tag as its iterator_category type, which would
+      // mean we select the __advance overload which cannot move backwards.
+      // A C++20 random_access_iterator we might select the O(n) __advance
+      // if it doesn't meet the Cpp17RandomAccessIterator requirements.
+      // So for C++20 iterator types we can just choose to do the right thing.
+      if constexpr (__detail::__promotable_iterator<_InputIterator>
+		      && ranges::__detail::__is_integer_like<_Distance>)
+	{
+	  auto __d = static_cast<iter_difference_t<_InputIterator>>(__n);
+	  if constexpr (random_access_iterator<_InputIterator>)
+	    std::__advance(__i, __d, random_access_iterator_tag());
+	  else if constexpr (bidirectional_iterator<_InputIterator>)
+	    std::__advance(__i, __d, bidirectional_iterator_tag());
+	  else
+	    std::__advance(__i, __d, input_iterator_tag());
+	}
+      else // assume it meets the Cpp17InputIterator requirements:
+#endif
+	{
+	  // concept requirements -- taken care of in __advance
+	  typename iterator_traits<_InputIterator>::difference_type __d = __n;
+	  std::__advance(__i, __d, std::__iterator_category(__i));
+	}
     }
 
 #if __cplusplus >= 201103L
diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h
index f2c1bce..7625333 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -1154,7 +1154,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       resize(size_type __new_size, const value_type& __x)
       {
 	if (__new_size > size())
-	  _M_fill_insert(end(), __new_size - size(), __x);
+	  _M_fill_append(__new_size - size(), __x);
 	else if (__new_size < size())
 	  _M_erase_at_end(this->_M_impl._M_start + __new_size);
       }
@@ -1175,7 +1175,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       resize(size_type __new_size, value_type __x = value_type())
       {
 	if (__new_size > size())
-	  _M_fill_insert(end(), __new_size - size(), __x);
+	  _M_fill_append(__new_size - size(), __x);
 	else if (__new_size < size())
 	  _M_erase_at_end(this->_M_impl._M_start + __new_size);
       }
@@ -2088,6 +2088,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       void
       _M_fill_insert(iterator __pos, size_type __n, const value_type& __x);
 
+      // Called by resize(n,x), and the _M_fill_insert(end(), n, x)
+      _GLIBCXX20_CONSTEXPR
+      void
+      _M_fill_append(size_type __n, const value_type& __x);
+
 #if __cplusplus >= 201103L
       // Called by resize(n).
       _GLIBCXX20_CONSTEXPR
diff --git a/libstdc++-v3/include/bits/utility.h b/libstdc++-v3/include/bits/utility.h
index 84d25e0..4e57465 100644
--- a/libstdc++-v3/include/bits/utility.h
+++ b/libstdc++-v3/include/bits/utility.h
@@ -137,26 +137,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     using tuple_element_t = typename tuple_element<__i, _Tp>::type;
 #endif
 
-  // Stores a tuple of indices.  Used by tuple and pair, and by bind() to
-  // extract the elements in a tuple.
-  template<size_t... _Indexes> struct _Index_tuple { };
-
-  // Builds an _Index_tuple<0, 1, 2, ..., _Num-1>.
-  template<size_t _Num>
-    struct _Build_index_tuple
-    {
-#if __has_builtin(__make_integer_seq)
-      template<typename, size_t... _Indices>
-	using _IdxTuple = _Index_tuple<_Indices...>;
-
-      // Clang defines __make_integer_seq for this purpose.
-      using __type = __make_integer_seq<_IdxTuple, size_t, _Num>;
-#else
-      // For GCC and other compilers, use __integer_pack instead.
-      using __type = _Index_tuple<__integer_pack(_Num)...>;
-#endif
-    };
-
 #ifdef __glibcxx_integer_sequence // C++ >= 14
 
   /// Class template integer_sequence
diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 70ead1d..642edb5 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -664,8 +664,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
     {
       if (__n != 0)
 	{
-	  if (size_type(this->_M_impl._M_end_of_storage
-			- this->_M_impl._M_finish) >= __n)
+	  if (__position.base() == this->_M_impl._M_finish)
+	    _M_fill_append(__n, __x);
+	  else if (size_type(this->_M_impl._M_end_of_storage
+			       - this->_M_impl._M_finish) >= __n)
 	    {
 #if __cplusplus < 201103L
 	      value_type __x_copy = __x;
@@ -760,6 +762,60 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	}
     }
 
+  template<typename _Tp, typename _Alloc>
+    _GLIBCXX20_CONSTEXPR
+    void
+    vector<_Tp, _Alloc>::
+    _M_fill_append(size_type __n, const value_type& __x)
+    {
+       if (size_type(this->_M_impl._M_end_of_storage
+		     - this->_M_impl._M_finish) >= __n)
+	 {
+	   _GLIBCXX_ASAN_ANNOTATE_GROW(__n);
+	   this->_M_impl._M_finish =
+	     std::__uninitialized_fill_n_a(this->_M_impl._M_finish, __n, __x,
+					   _M_get_Tp_allocator());
+	   _GLIBCXX_ASAN_ANNOTATE_GREW(__n);
+	 }
+       else
+	 {
+	   // Make local copies of these members because the compiler thinks
+	   // the allocator can alter them if 'this' is globally reachable.
+	   pointer __old_start = this->_M_impl._M_start;
+	   pointer __old_finish = this->_M_impl._M_finish;
+	   const size_type __old_size = __old_finish - __old_start;
+
+	   const size_type __len =
+	     _M_check_len(__n, "vector::_M_fill_append");
+	   pointer __new_start(this->_M_allocate(__len));
+	   pointer __new_finish(__new_start + __old_size);
+	   __try
+	     {
+	       // See _M_realloc_insert above.
+	       __new_finish = std::__uninitialized_fill_n_a(
+				__new_finish, __n, __x,
+				_M_get_Tp_allocator());
+	       std::__uninitialized_move_if_noexcept_a(
+		 __old_start, __old_finish, __new_start,
+		 _M_get_Tp_allocator());
+	     }
+	   __catch(...)
+	     {
+		std::_Destroy(__new_start + __old_size, __new_finish,
+			      _M_get_Tp_allocator());
+		_M_deallocate(__new_start, __len);
+		__throw_exception_again;
+	      }
+	   std::_Destroy(__old_start, __old_finish, _M_get_Tp_allocator());
+	   _GLIBCXX_ASAN_ANNOTATE_REINIT;
+	   _M_deallocate(__old_start,
+			 this->_M_impl._M_end_of_storage - __old_start);
+	   this->_M_impl._M_start = __new_start;
+	   this->_M_impl._M_finish = __new_finish;
+	   this->_M_impl._M_end_of_storage = __new_start + __len;
+	 }
+    }
+
 #if __cplusplus >= 201103L
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
@@ -1007,15 +1063,18 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 
 	if constexpr (ranges::forward_range<_Rg>)
 	  {
+	    const auto __ins_idx = __pos - cbegin();
+	    // Number of new elements to insert:
+	    const auto __n = size_type(ranges::distance(__rg));
+	    if (__n == 0)
+	      return begin() + __ins_idx;
+
 	    // Start of existing elements:
 	    pointer __old_start = this->_M_impl._M_start;
 	    // End of existing elements:
 	    pointer __old_finish = this->_M_impl._M_finish;
 	    // Insertion point:
-	    const auto __ins_idx = __pos - cbegin();
 	    pointer __ins = __old_start + __ins_idx;
-	    // Number of new elements to insert:
-	    const auto __n = size_type(ranges::distance(__rg));
 	    // Number of elements that can fit in unused capacity:
 	    const auto __cap = this->_M_impl._M_end_of_storage - __old_finish;
 	    if (__cap >= __n)
diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index dbe2cb8..84c755d 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -733,6 +733,14 @@ ftms = {
 };
 
 ftms = {
+  name = is_sufficiently_aligned;
+  values = {
+    v = 202411;
+    cxxmin = 26;
+  };
+};
+
+ftms = {
   name = atomic_flag_test;
   values = {
     v = 201907;
@@ -1008,12 +1016,26 @@ ftms = {
 ftms = {
   name = mdspan;
   values = {
+    v = 202406;
+    cxxmin = 26;
+  };
+  values = {
     v = 202207;
     cxxmin = 23;
   };
 };
 
 ftms = {
+  name = aligned_accessor;
+  values = {
+    v = 202411;
+    cxxmin = 26;
+    extra_cond = "__glibcxx_assume_aligned "
+    "&& __glibcxx_is_sufficiently_aligned";
+  };
+};
+
+ftms = {
   name = ssize;
   values = {
     v = 201902;
@@ -1885,6 +1907,14 @@ ftms = {
 };
 
 ftms = {
+  name = debugging;
+  values = {
+    v = 202403;
+    cxxmin = 26;
+  };
+};
+
+ftms = {
   name = fstream_native_handle;
   values = {
     v = 202306;
diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index 7bb6016..410e320 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -815,6 +815,16 @@
 #endif /* !defined(__cpp_lib_assume_aligned) && defined(__glibcxx_want_assume_aligned) */
 #undef __glibcxx_want_assume_aligned
 
+#if !defined(__cpp_lib_is_sufficiently_aligned)
+# if (__cplusplus >  202302L)
+#  define __glibcxx_is_sufficiently_aligned 202411L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_is_sufficiently_aligned)
+#   define __cpp_lib_is_sufficiently_aligned 202411L
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_is_sufficiently_aligned) && defined(__glibcxx_want_is_sufficiently_aligned) */
+#undef __glibcxx_want_is_sufficiently_aligned
+
 #if !defined(__cpp_lib_atomic_flag_test)
 # if (__cplusplus >= 202002L)
 #  define __glibcxx_atomic_flag_test 201907L
@@ -1125,7 +1135,12 @@
 #undef __glibcxx_want_span
 
 #if !defined(__cpp_lib_mdspan)
-# if (__cplusplus >= 202100L)
+# if (__cplusplus >  202302L)
+#  define __glibcxx_mdspan 202406L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_mdspan)
+#   define __cpp_lib_mdspan 202406L
+#  endif
+# elif (__cplusplus >= 202100L)
 #  define __glibcxx_mdspan 202207L
 #  if defined(__glibcxx_want_all) || defined(__glibcxx_want_mdspan)
 #   define __cpp_lib_mdspan 202207L
@@ -1134,6 +1149,16 @@
 #endif /* !defined(__cpp_lib_mdspan) && defined(__glibcxx_want_mdspan) */
 #undef __glibcxx_want_mdspan
 
+#if !defined(__cpp_lib_aligned_accessor)
+# if (__cplusplus >  202302L) && (__glibcxx_assume_aligned && __glibcxx_is_sufficiently_aligned)
+#  define __glibcxx_aligned_accessor 202411L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_aligned_accessor)
+#   define __cpp_lib_aligned_accessor 202411L
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_aligned_accessor) && defined(__glibcxx_want_aligned_accessor) */
+#undef __glibcxx_want_aligned_accessor
+
 #if !defined(__cpp_lib_ssize)
 # if (__cplusplus >= 202002L)
 #  define __glibcxx_ssize 201902L
@@ -2109,6 +2134,16 @@
 #endif /* !defined(__cpp_lib_constexpr_new) && defined(__glibcxx_want_constexpr_new) */
 #undef __glibcxx_want_constexpr_new
 
+#if !defined(__cpp_lib_debugging)
+# if (__cplusplus >  202302L)
+#  define __glibcxx_debugging 202403L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_debugging)
+#   define __cpp_lib_debugging 202403L
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_debugging) && defined(__glibcxx_want_debugging) */
+#undef __glibcxx_want_debugging
+
 #if !defined(__cpp_lib_fstream_native_handle)
 # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED
 #  define __glibcxx_fstream_native_handle 202306L