diff --git a/libcxx/include/__algorithm/clamp.h b/libcxx/include/__algorithm/clamp.h
index 1a5a3d0744be..cf7cd507a149 100644
--- a/libcxx/include/__algorithm/clamp.h
+++ b/libcxx/include/__algorithm/clamp.h
@@ -17,9 +17,10 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER >= 17
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 17
 template <class _Tp, class _Compare>
 [[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&
 clamp(_LIBCPP_LIFETIMEBOUND const _Tp& __v,
@@ -37,8 +38,9 @@ clamp(_LIBCPP_LIFETIMEBOUND const _Tp& __v,
       _LIBCPP_LIFETIMEBOUND const _Tp& __hi) {
   return std::clamp(__v, __lo, __hi, __less<>());
 }
-#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___ALGORITHM_CLAMP_H
diff --git a/libcxx/include/__algorithm/lexicographical_compare_three_way.h b/libcxx/include/__algorithm/lexicographical_compare_three_way.h
index 442223e79e4e..5be95c4d5134 100644
--- a/libcxx/include/__algorithm/lexicographical_compare_three_way.h
+++ b/libcxx/include/__algorithm/lexicographical_compare_three_way.h
@@ -27,10 +27,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // Fast path for random access iterators which computes the number of loop iterations up-front and
 // then skips the iterator comparisons inside the loop.
 template <class _InputIterator1, class _InputIterator2, class _Cmp>
@@ -116,10 +116,10 @@ template <class _InputIterator1, class _InputIterator2>
       std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), std::compare_three_way());
 }
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_THREE_WAY_H
diff --git a/libcxx/include/__algorithm/out_value_result.h b/libcxx/include/__algorithm/out_value_result.h
index 9e1e0e07286d..398328b04206 100644
--- a/libcxx/include/__algorithm/out_value_result.h
+++ b/libcxx/include/__algorithm/out_value_result.h
@@ -21,10 +21,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 template <class _OutIter1, class _ValType1>
@@ -47,10 +47,10 @@ struct out_value_result {
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___ALGORITHM_OUT_VALUE_RESULT_H
diff --git a/libcxx/include/__algorithm/radix_sort.h b/libcxx/include/__algorithm/radix_sort.h
index 5549a69f5e22..4f685ea162d5 100644
--- a/libcxx/include/__algorithm/radix_sort.h
+++ b/libcxx/include/__algorithm/radix_sort.h
@@ -67,10 +67,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 14
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _InputIterator, class _OutputIterator>
 _LIBCPP_HIDE_FROM_ABI constexpr pair<_OutputIterator, __iterator_value_type<_InputIterator>>
 __partial_sum_max(_InputIterator __first, _InputIterator __last, _OutputIterator __result) {
@@ -422,10 +422,10 @@ __radix_sort(_RandomAccessIterator1 __first, _RandomAccessIterator1 __last, _Ran
   std::__radix_sort(__first, __last, __buffer, __identity{}, __low_byte_fn{});
 }
 
-#endif // _LIBCPP_STD_VER >= 14
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 14
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___ALGORITHM_RADIX_SORT_H
diff --git a/libcxx/include/__algorithm/ranges_copy_n.h b/libcxx/include/__algorithm/ranges_copy_n.h
index e402cd6c2c0e..1720ac358fa4 100644
--- a/libcxx/include/__algorithm/ranges_copy_n.h
+++ b/libcxx/include/__algorithm/ranges_copy_n.h
@@ -24,10 +24,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 template <class _Ip, class _Op>
@@ -47,10 +47,10 @@ inline constexpr auto copy_n = __copy_n{};
 } // namespace __cpo
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___ALGORITHM_RANGES_COPY_N_H
diff --git a/libcxx/include/__algorithm/three_way_comp_ref_type.h b/libcxx/include/__algorithm/three_way_comp_ref_type.h
index f6f76455e466..8df3f1d6e3b2 100644
--- a/libcxx/include/__algorithm/three_way_comp_ref_type.h
+++ b/libcxx/include/__algorithm/three_way_comp_ref_type.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Comp>
 struct __debug_three_way_comp {
   _Comp& __comp_;
@@ -67,8 +67,8 @@ template <class _Comp>
 using __three_way_comp_ref_type _LIBCPP_NODEBUG = _Comp&;
 #  endif
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___ALGORITHM_THREE_WAY_COMP_REF_TYPE_H
diff --git a/libcxx/include/__atomic/atomic_sync.h b/libcxx/include/__atomic/atomic_sync.h
index b9b67d9092c6..c96cd63a82e3 100644
--- a/libcxx/include/__atomic/atomic_sync.h
+++ b/libcxx/include/__atomic/atomic_sync.h
@@ -23,9 +23,10 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER >= 20
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
 #  if _LIBCPP_HAS_THREADS
 
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
@@ -258,8 +259,8 @@ _LIBCPP_HIDE_FROM_ABI void __atomic_wait(_AtomicWaitable& __a, _Tp __val, memory
   });
 }
 
-#endif // C++20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___ATOMIC_ATOMIC_SYNC_H
diff --git a/libcxx/include/__atomic/atomic_sync_timed.h b/libcxx/include/__atomic/atomic_sync_timed.h
index 7cb24151fde7..4fed3bf53f68 100644
--- a/libcxx/include/__atomic/atomic_sync_timed.h
+++ b/libcxx/include/__atomic/atomic_sync_timed.h
@@ -25,10 +25,11 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
-#  if _LIBCPP_HAS_THREADS && _LIBCPP_AVAILABILITY_HAS_NEW_SYNC
+#  if _LIBCPP_AVAILABILITY_HAS_NEW_SYNC
 
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_AVAILABILITY_NEW_SYNC
@@ -110,7 +111,7 @@ _LIBCPP_HIDE_FROM_ABI bool __atomic_wait_unless_with_timeout(
   return __poll_result == __poll_with_backoff_results::__poll_success;
 }
 
-#  elif _LIBCPP_HAS_THREADS // _LIBCPP_HAS_THREADS && _LIBCPP_AVAILABILITY_HAS_NEW_SYNC
+#  else // _LIBCPP_AVAILABILITY_HAS_NEW_SYNC
 
 template <class _AtomicWaitable, class _Poll, class _Rep, class _Period>
 _LIBCPP_HIDE_FROM_ABI bool __atomic_wait_unless_with_timeout(
@@ -129,10 +130,10 @@ _LIBCPP_HIDE_FROM_ABI bool __atomic_wait_unless_with_timeout(
   return __res == __poll_with_backoff_results::__poll_success;
 }
 
-#  endif // _LIBCPP_HAS_THREADS && _LIBCPP_AVAILABILITY_HAS_NEW_SYNC
-
-#endif // C++20
+#  endif // _LIBCPP_AVAILABILITY_HAS_NEW_SYNC
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
+
 #endif // _LIBCPP___ATOMIC_ATOMIC_SYNC_TIMED_H
diff --git a/libcxx/include/__atomic/atomic_waitable_traits.h b/libcxx/include/__atomic/atomic_waitable_traits.h
index 369cd2c52b83..ed26a60df982 100644
--- a/libcxx/include/__atomic/atomic_waitable_traits.h
+++ b/libcxx/include/__atomic/atomic_waitable_traits.h
@@ -22,10 +22,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // The customisation points to enable the following functions:
 // - __atomic_wait
 // - __atomic_wait_unless
@@ -94,8 +94,8 @@ concept __has_native_atomic_wait = is_same_v<_Tp, __cxx_contention_t>;
 
 #  endif // _LIBCPP_ABI_ATOMIC_WAIT_NATIVE_BY_SIZE
 
-#endif // C++20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___ATOMIC_ATOMIC_WAITABLE_TRAITS_H
diff --git a/libcxx/include/__atomic/floating_point_helper.h b/libcxx/include/__atomic/floating_point_helper.h
index 8762ec234b18..4f21006dd27d 100644
--- a/libcxx/include/__atomic/floating_point_helper.h
+++ b/libcxx/include/__atomic/floating_point_helper.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr bool __is_fp80_long_double() {
   // Only x87-fp80 long double has 64-bit mantissa
@@ -48,8 +48,8 @@ _LIBCPP_HIDE_FROM_ABI constexpr bool __has_rmw_builtin() {
 #  endif
 }
 
-#endif
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___ATOMIC_FLOATING_POINT_HELPER_H
diff --git a/libcxx/include/__bit/bit_cast.h b/libcxx/include/__bit/bit_cast.h
index 735025065a72..72b558f1446c 100644
--- a/libcxx/include/__bit/bit_cast.h
+++ b/libcxx/include/__bit/bit_cast.h
@@ -17,18 +17,16 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #ifndef _LIBCPP_CXX03_LANG
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _ToType, class _FromType>
 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI constexpr _ToType __bit_cast(const _FromType& __from) noexcept {
   return __builtin_bit_cast(_ToType, __from);
 }
 
-#endif // _LIBCPP_CXX03_LANG
-
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
 
 template <class _ToType, class _FromType>
   requires(sizeof(_ToType) == sizeof(_FromType) && is_trivially_copyable_v<_ToType> &&
@@ -37,8 +35,10 @@ template <class _ToType, class _FromType>
   return __builtin_bit_cast(_ToType, __from);
 }
 
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_CXX03_LANG
+
 #endif // _LIBCPP___BIT_BIT_CAST_H
diff --git a/libcxx/include/__bit/bit_ceil.h b/libcxx/include/__bit/bit_ceil.h
index 99881a853829..73238eb2c37d 100644
--- a/libcxx/include/__bit/bit_ceil.h
+++ b/libcxx/include/__bit/bit_ceil.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp>
 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp __bit_ceil(_Tp __t) noexcept {
   if (__t < 2)
@@ -47,8 +47,9 @@ template <__unsigned_integer _Tp>
 }
 
 #  endif // _LIBCPP_STD_VER >= 20
-#endif   // _LIBCPP_STD_VER >= 17
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___BIT_BIT_CEIL_H
diff --git a/libcxx/include/__charconv/to_chars.h b/libcxx/include/__charconv/to_chars.h
index 8ef09af73755..0a94ba14addc 100644
--- a/libcxx/include/__charconv/to_chars.h
+++ b/libcxx/include/__charconv/to_chars.h
@@ -18,8 +18,4 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-_LIBCPP_END_NAMESPACE_STD
-
 #endif // _LIBCPP___CHARCONV_TO_CHARS
diff --git a/libcxx/include/__chrono/gps_clock.h b/libcxx/include/__chrono/gps_clock.h
index 2e220cab946e..924156ae5b45 100644
--- a/libcxx/include/__chrono/gps_clock.h
+++ b/libcxx/include/__chrono/gps_clock.h
@@ -28,10 +28,10 @@
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace chrono {
 
 class gps_clock;
@@ -78,11 +78,11 @@ public:
 
 } // namespace chrono
 
+_LIBCPP_END_NAMESPACE_STD
+
 #  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
          // _LIBCPP_HAS_LOCALIZATION
 
-_LIBCPP_END_NAMESPACE_STD
-
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB
diff --git a/libcxx/include/__chrono/steady_clock.h b/libcxx/include/__chrono/steady_clock.h
index ed530815dc4c..b433b0b3ad29 100644
--- a/libcxx/include/__chrono/steady_clock.h
+++ b/libcxx/include/__chrono/steady_clock.h
@@ -18,12 +18,13 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_HAS_MONOTONIC_CLOCK
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
 namespace chrono {
 
-#if _LIBCPP_HAS_MONOTONIC_CLOCK
 class _LIBCPP_EXPORTED_FROM_ABI steady_clock {
 public:
   typedef nanoseconds duration;
@@ -34,11 +35,12 @@ public:
 
   [[__nodiscard__]] static time_point now() _NOEXCEPT;
 };
-#endif
 
 } // namespace chrono
 
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
 
+#endif
+
 #endif // _LIBCPP___CHRONO_STEADY_CLOCK_H
diff --git a/libcxx/include/__chrono/tai_clock.h b/libcxx/include/__chrono/tai_clock.h
index 14c8b70a94af..9c97e379f4b9 100644
--- a/libcxx/include/__chrono/tai_clock.h
+++ b/libcxx/include/__chrono/tai_clock.h
@@ -28,10 +28,10 @@
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace chrono {
 
 class tai_clock;
@@ -96,11 +96,11 @@ public:
 
 } // namespace chrono
 
+_LIBCPP_END_NAMESPACE_STD
+
 #  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
          // _LIBCPP_HAS_LOCALIZATION
 
-_LIBCPP_END_NAMESPACE_STD
-
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB
diff --git a/libcxx/include/__chrono/time_zone.h b/libcxx/include/__chrono/time_zone.h
index 20f3297f772b..742367defb21 100644
--- a/libcxx/include/__chrono/time_zone.h
+++ b/libcxx/include/__chrono/time_zone.h
@@ -35,11 +35,11 @@
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
+#  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
-#  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
-
 namespace chrono {
 
 enum class choose { earliest, latest };
@@ -174,12 +174,12 @@ operator<=>(const time_zone& __x, const time_zone& __y) noexcept {
 
 } // namespace chrono
 
-#  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
-         // _LIBCPP_HAS_LOCALIZATION
-
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
+         // _LIBCPP_HAS_LOCALIZATION
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB
diff --git a/libcxx/include/__chrono/time_zone_link.h b/libcxx/include/__chrono/time_zone_link.h
index cae40b07c2ca..3c45d953fb7e 100644
--- a/libcxx/include/__chrono/time_zone_link.h
+++ b/libcxx/include/__chrono/time_zone_link.h
@@ -29,10 +29,10 @@
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace chrono {
 
 class time_zone_link {
@@ -67,11 +67,11 @@ operator<=>(const time_zone_link& __x, const time_zone_link& __y) noexcept {
 
 } // namespace chrono
 
+_LIBCPP_END_NAMESPACE_STD
+
 #  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
          // _LIBCPP_HAS_LOCALIZATION
 
-_LIBCPP_END_NAMESPACE_STD
-
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB
diff --git a/libcxx/include/__chrono/tzdb.h b/libcxx/include/__chrono/tzdb.h
index 2fa04604b91f..6e713a8ff3dd 100644
--- a/libcxx/include/__chrono/tzdb.h
+++ b/libcxx/include/__chrono/tzdb.h
@@ -34,11 +34,11 @@
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
+#  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
-#  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
-
 namespace chrono {
 
 struct tzdb {
@@ -85,12 +85,12 @@ private:
 
 } // namespace chrono
 
-#  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
-         // _LIBCPP_HAS_LOCALIZATION
-
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
+         // _LIBCPP_HAS_LOCALIZATION
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB
diff --git a/libcxx/include/__chrono/tzdb_list.h b/libcxx/include/__chrono/tzdb_list.h
index 997599ac7496..64b2f4995c08 100644
--- a/libcxx/include/__chrono/tzdb_list.h
+++ b/libcxx/include/__chrono/tzdb_list.h
@@ -27,11 +27,11 @@
 #    pragma GCC system_header
 #  endif
 
+#  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
-#  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
-
 namespace chrono {
 
 // TODO TZDB
@@ -99,12 +99,12 @@ _LIBCPP_AVAILABILITY_TZDB _LIBCPP_EXPORTED_FROM_ABI const tzdb& reload_tzdb();
 
 } // namespace chrono
 
-#  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
-         // _LIBCPP_HAS_LOCALIZATION
-
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
+         // _LIBCPP_HAS_LOCALIZATION
+
 #endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB
 
 #endif // _LIBCPP___CHRONO_TZDB_LIST_H
diff --git a/libcxx/include/__chrono/utc_clock.h b/libcxx/include/__chrono/utc_clock.h
index 2207b89c92c5..42cb41ea9a6f 100644
--- a/libcxx/include/__chrono/utc_clock.h
+++ b/libcxx/include/__chrono/utc_clock.h
@@ -27,10 +27,10 @@
 #    pragma GCC system_header
 #  endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace chrono {
 
 class utc_clock;
@@ -153,11 +153,11 @@ utc_clock::to_sys(const utc_time<_Duration>& __time) {
 
 } // namespace chrono
 
+_LIBCPP_END_NAMESPACE_STD
+
 #  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
          // _LIBCPP_HAS_LOCALIZATION
 
-_LIBCPP_END_NAMESPACE_STD
-
 #endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB
 
 #endif // _LIBCPP___CHRONO_UTC_CLOCK_H
diff --git a/libcxx/include/__chrono/zoned_time.h b/libcxx/include/__chrono/zoned_time.h
index e63528e57d1c..c1488320775f 100644
--- a/libcxx/include/__chrono/zoned_time.h
+++ b/libcxx/include/__chrono/zoned_time.h
@@ -40,10 +40,10 @@
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace chrono {
 
 template <class>
@@ -232,11 +232,11 @@ struct hash<chrono::zoned_time<_Duration, _TimeZonePtr>> {
 
 #    endif // _LIBCPP_STD_VER >= 26
 
+_LIBCPP_END_NAMESPACE_STD
+
 #  endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM &&
          // _LIBCPP_HAS_LOCALIZATION
 
-_LIBCPP_END_NAMESPACE_STD
-
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP_HAS_EXPERIMENTAL_TZDB
diff --git a/libcxx/include/__compare/common_comparison_category.h b/libcxx/include/__compare/common_comparison_category.h
index eae2ef00624b..f785a27fd28e 100644
--- a/libcxx/include/__compare/common_comparison_category.h
+++ b/libcxx/include/__compare/common_comparison_category.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace __comp_detail {
 
 enum _ClassifyCompCategory : unsigned { _None, _PartialOrd, _WeakOrd, _StrongOrd, _CCC_Size };
@@ -79,8 +79,8 @@ struct common_comparison_category {
 template <class... _Ts>
 using common_comparison_category_t = typename common_comparison_category<_Ts...>::type;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___COMPARE_COMMON_COMPARISON_CATEGORY_H
diff --git a/libcxx/include/__compare/compare_three_way.h b/libcxx/include/__compare/compare_three_way.h
index 852c5874c61c..6999000e9dce 100644
--- a/libcxx/include/__compare/compare_three_way.h
+++ b/libcxx/include/__compare/compare_three_way.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 struct compare_three_way {
   template <class _T1, class _T2>
     requires three_way_comparable_with<_T1, _T2>
@@ -33,8 +33,8 @@ struct compare_three_way {
   using is_transparent = void;
 };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___COMPARE_COMPARE_THREE_WAY_H
diff --git a/libcxx/include/__compare/compare_three_way_result.h b/libcxx/include/__compare/compare_three_way_result.h
index 264a4d603ca4..ab04e03490e2 100644
--- a/libcxx/include/__compare/compare_three_way_result.h
+++ b/libcxx/include/__compare/compare_three_way_result.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class, class, class>
 struct _LIBCPP_HIDE_FROM_ABI __compare_three_way_result {};
 
@@ -39,8 +39,8 @@ struct _LIBCPP_NO_SPECIALIZATIONS compare_three_way_result : __compare_three_way
 template <class _Tp, class _Up = _Tp>
 using compare_three_way_result_t = typename compare_three_way_result<_Tp, _Up>::type;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___COMPARE_COMPARE_THREE_WAY_RESULT_H
diff --git a/libcxx/include/__compare/ordering.h b/libcxx/include/__compare/ordering.h
index 902ef5329dd4..226b513586bb 100644
--- a/libcxx/include/__compare/ordering.h
+++ b/libcxx/include/__compare/ordering.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // exposition only
 enum class _OrdResult : signed char { __less = -1, __equiv = 0, __greater = 1 };
 
@@ -275,8 +275,8 @@ template <class _Tp>
 concept __comparison_category =
     is_same_v<_Tp, partial_ordering> || is_same_v<_Tp, weak_ordering> || is_same_v<_Tp, strong_ordering>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___COMPARE_ORDERING_H
diff --git a/libcxx/include/__compare/synth_three_way.h b/libcxx/include/__compare/synth_three_way.h
index 63bf56d0cf42..e1c2642fbdf2 100644
--- a/libcxx/include/__compare/synth_three_way.h
+++ b/libcxx/include/__compare/synth_three_way.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [expos.only.func]
 
 _LIBCPP_HIDE_FROM_ABI inline constexpr auto __synth_three_way = []<class _Tp, class _Up>(const _Tp& __t, const _Up& __u)
@@ -46,8 +46,8 @@ template <class _Tp, class _Up = _Tp>
 using __synth_three_way_result _LIBCPP_NODEBUG =
     decltype(std::__synth_three_way(std::declval<_Tp&>(), std::declval<_Up&>()));
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___COMPARE_SYNTH_THREE_WAY_H
diff --git a/libcxx/include/__compare/three_way_comparable.h b/libcxx/include/__compare/three_way_comparable.h
index ad6d05a68114..5eb0058708fc 100644
--- a/libcxx/include/__compare/three_way_comparable.h
+++ b/libcxx/include/__compare/three_way_comparable.h
@@ -24,10 +24,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp, class _Cat>
 concept __compares_as = same_as<common_comparison_category_t<_Tp, _Cat>, _Cat>;
 
@@ -48,8 +48,8 @@ concept three_way_comparable_with =
       { __u <=> __t } -> __compares_as<_Cat>;
     };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___COMPARE_THREE_WAY_COMPARABLE_H
diff --git a/libcxx/include/__concepts/arithmetic.h b/libcxx/include/__concepts/arithmetic.h
index 64c0200783df..addbefa7e11a 100644
--- a/libcxx/include/__concepts/arithmetic.h
+++ b/libcxx/include/__concepts/arithmetic.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concepts.arithmetic], arithmetic concepts
 
 template <class _Tp>
@@ -36,8 +36,8 @@ concept unsigned_integral = integral<_Tp> && !signed_integral<_Tp>;
 template <class _Tp>
 concept floating_point = is_floating_point_v<_Tp>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_ARITHMETIC_H
diff --git a/libcxx/include/__concepts/assignable.h b/libcxx/include/__concepts/assignable.h
index 7423daabba78..70f0bc3b0c95 100644
--- a/libcxx/include/__concepts/assignable.h
+++ b/libcxx/include/__concepts/assignable.h
@@ -20,10 +20,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.assignable]
 
 template <class _Lhs, class _Rhs>
@@ -34,8 +34,8 @@ concept assignable_from =
       { __lhs = std::forward<_Rhs>(__rhs) } -> same_as<_Lhs>;
     };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_ASSIGNABLE_H
diff --git a/libcxx/include/__concepts/boolean_testable.h b/libcxx/include/__concepts/boolean_testable.h
index b379fe9c5a88..458e4c1da725 100644
--- a/libcxx/include/__concepts/boolean_testable.h
+++ b/libcxx/include/__concepts/boolean_testable.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concepts.booleantestable]
 
 template <class _Tp>
@@ -31,8 +31,8 @@ concept __boolean_testable = __boolean_testable_impl<_Tp> && requires(_Tp&& __t)
   { !std::forward<_Tp>(__t) } -> __boolean_testable_impl;
 };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_BOOLEAN_TESTABLE_H
diff --git a/libcxx/include/__concepts/class_or_enum.h b/libcxx/include/__concepts/class_or_enum.h
index 9fceed034c46..920bf8a6fa70 100644
--- a/libcxx/include/__concepts/class_or_enum.h
+++ b/libcxx/include/__concepts/class_or_enum.h
@@ -18,17 +18,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // Whether a type is a class type or enumeration type according to the Core wording.
 
 template <class _Tp>
 concept __class_or_enum = is_class_v<_Tp> || is_union_v<_Tp> || is_enum_v<_Tp>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_CLASS_OR_ENUM_H
diff --git a/libcxx/include/__concepts/common_reference_with.h b/libcxx/include/__concepts/common_reference_with.h
index 4eb687e071bc..613de04b7b5b 100644
--- a/libcxx/include/__concepts/common_reference_with.h
+++ b/libcxx/include/__concepts/common_reference_with.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.commonref]
 
 template <class _Tp, class _Up>
@@ -29,8 +29,8 @@ concept common_reference_with =
     same_as<common_reference_t<_Tp, _Up>, common_reference_t<_Up, _Tp>> &&
     convertible_to<_Tp, common_reference_t<_Tp, _Up>> && convertible_to<_Up, common_reference_t<_Tp, _Up>>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H
diff --git a/libcxx/include/__concepts/comparison_common_type.h b/libcxx/include/__concepts/comparison_common_type.h
index 3f0d770511f4..d06a8dc8786f 100644
--- a/libcxx/include/__concepts/comparison_common_type.h
+++ b/libcxx/include/__concepts/comparison_common_type.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp, class _Up, class _CommonRef = common_reference_t<const _Tp&, const _Up&>>
 concept __comparison_common_type_with_impl =
     same_as<common_reference_t<const _Tp&, const _Up&>, common_reference_t<const _Up&, const _Tp&>> && requires {
@@ -33,8 +33,8 @@ concept __comparison_common_type_with_impl =
 template <class _Tp, class _Up>
 concept __comparison_common_type_with = __comparison_common_type_with_impl<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_COMPARISON_COMMON_TYPE_H
diff --git a/libcxx/include/__concepts/constructible.h b/libcxx/include/__concepts/constructible.h
index 835a44429c09..7b39c80304bc 100644
--- a/libcxx/include/__concepts/constructible.h
+++ b/libcxx/include/__concepts/constructible.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.constructible]
 template <class _Tp, class... _Args>
 concept constructible_from = destructible<_Tp> && is_constructible_v<_Tp, _Args...>;
@@ -48,8 +48,8 @@ concept copy_constructible =
     constructible_from<_Tp, const _Tp> && convertible_to<const _Tp, _Tp>;
 // clang-format on
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_CONSTRUCTIBLE_H
diff --git a/libcxx/include/__concepts/convertible_to.h b/libcxx/include/__concepts/convertible_to.h
index 6d5b6c1268d5..01e3cfa2a3bf 100644
--- a/libcxx/include/__concepts/convertible_to.h
+++ b/libcxx/include/__concepts/convertible_to.h
@@ -17,17 +17,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.convertible]
 
 template <class _From, class _To>
 concept convertible_to = is_convertible_v<_From, _To> && requires { static_cast<_To>(std::declval<_From>()); };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_CONVERTIBLE_TO_H
diff --git a/libcxx/include/__concepts/copyable.h b/libcxx/include/__concepts/copyable.h
index 2bf0ad42fc1a..3bcee3422902 100644
--- a/libcxx/include/__concepts/copyable.h
+++ b/libcxx/include/__concepts/copyable.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concepts.object]
 
 // clang-format off
@@ -34,8 +34,8 @@ concept copyable =
     assignable_from<_Tp&, const _Tp>;
 // clang-format on
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_COPYABLE_H
diff --git a/libcxx/include/__concepts/derived_from.h b/libcxx/include/__concepts/derived_from.h
index 9875faee81b9..418f5db8ba9a 100644
--- a/libcxx/include/__concepts/derived_from.h
+++ b/libcxx/include/__concepts/derived_from.h
@@ -17,17 +17,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.derived]
 
 template <class _Dp, class _Bp>
 concept derived_from = is_base_of_v<_Bp, _Dp> && is_convertible_v<const volatile _Dp*, const volatile _Bp*>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_DERIVED_FROM_H
diff --git a/libcxx/include/__concepts/destructible.h b/libcxx/include/__concepts/destructible.h
index 28b4b1bc24ec..1db7f6a0a7c7 100644
--- a/libcxx/include/__concepts/destructible.h
+++ b/libcxx/include/__concepts/destructible.h
@@ -16,17 +16,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.destructible]
 
 template <class _Tp>
 concept destructible = is_nothrow_destructible_v<_Tp>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_DESTRUCTIBLE_H
diff --git a/libcxx/include/__concepts/different_from.h b/libcxx/include/__concepts/different_from.h
index fd31f6e25805..f9888c918d7c 100644
--- a/libcxx/include/__concepts/different_from.h
+++ b/libcxx/include/__concepts/different_from.h
@@ -17,15 +17,15 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp, class _Up>
 concept __different_from = !same_as<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_DIFFERENT_FROM_H
diff --git a/libcxx/include/__concepts/equality_comparable.h b/libcxx/include/__concepts/equality_comparable.h
index 56fc6f8b685c..411a19c60ddd 100644
--- a/libcxx/include/__concepts/equality_comparable.h
+++ b/libcxx/include/__concepts/equality_comparable.h
@@ -20,10 +20,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.equalitycomparable]
 
 template <class _Tp, class _Up>
@@ -50,8 +50,8 @@ concept equality_comparable_with =
     __weakly_equality_comparable_with<_Tp, _Up>;
 // clang-format on
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_EQUALITY_COMPARABLE_H
diff --git a/libcxx/include/__concepts/invocable.h b/libcxx/include/__concepts/invocable.h
index 8a29398b3a29..92b2ec56affa 100644
--- a/libcxx/include/__concepts/invocable.h
+++ b/libcxx/include/__concepts/invocable.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.invocable]
 
 template <class _Fn, class... _Args>
@@ -33,8 +33,8 @@ concept invocable = requires(_Fn&& __fn, _Args&&... __args) {
 template <class _Fn, class... _Args>
 concept regular_invocable = invocable<_Fn, _Args...>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_INVOCABLE_H
diff --git a/libcxx/include/__concepts/movable.h b/libcxx/include/__concepts/movable.h
index bc5b9d767c6a..f38ab37be89a 100644
--- a/libcxx/include/__concepts/movable.h
+++ b/libcxx/include/__concepts/movable.h
@@ -19,17 +19,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concepts.object]
 
 template <class _Tp>
 concept movable = is_object_v<_Tp> && move_constructible<_Tp> && assignable_from<_Tp&, _Tp> && swappable<_Tp>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_MOVABLE_H
diff --git a/libcxx/include/__concepts/predicate.h b/libcxx/include/__concepts/predicate.h
index e0263a878b06..9e903a9efdb2 100644
--- a/libcxx/include/__concepts/predicate.h
+++ b/libcxx/include/__concepts/predicate.h
@@ -18,17 +18,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.predicate]
 
 template <class _Fn, class... _Args>
 concept predicate = regular_invocable<_Fn, _Args...> && __boolean_testable<invoke_result_t<_Fn, _Args...>>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_PREDICATE_H
diff --git a/libcxx/include/__concepts/regular.h b/libcxx/include/__concepts/regular.h
index 9f3d8bf30be3..ab4f68e8f460 100644
--- a/libcxx/include/__concepts/regular.h
+++ b/libcxx/include/__concepts/regular.h
@@ -17,17 +17,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.object]
 
 template <class _Tp>
 concept regular = semiregular<_Tp> && equality_comparable<_Tp>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_REGULAR_H
diff --git a/libcxx/include/__concepts/relation.h b/libcxx/include/__concepts/relation.h
index 7545a7db93da..ccd3643e81fc 100644
--- a/libcxx/include/__concepts/relation.h
+++ b/libcxx/include/__concepts/relation.h
@@ -16,10 +16,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.relation]
 
 template <class _Rp, class _Tp, class _Up>
@@ -36,8 +36,8 @@ concept equivalence_relation = relation<_Rp, _Tp, _Up>;
 template <class _Rp, class _Tp, class _Up>
 concept strict_weak_order = relation<_Rp, _Tp, _Up>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_RELATION_H
diff --git a/libcxx/include/__concepts/same_as.h b/libcxx/include/__concepts/same_as.h
index 4241131c70c1..1385e4d84fdf 100644
--- a/libcxx/include/__concepts/same_as.h
+++ b/libcxx/include/__concepts/same_as.h
@@ -16,10 +16,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.same]
 
 template <class _Tp, class _Up>
@@ -28,8 +28,8 @@ concept __same_as_impl = _IsSame<_Tp, _Up>::value;
 template <class _Tp, class _Up>
 concept same_as = __same_as_impl<_Tp, _Up> && __same_as_impl<_Up, _Tp>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_SAME_AS_H
diff --git a/libcxx/include/__concepts/semiregular.h b/libcxx/include/__concepts/semiregular.h
index 7a159d17dfc1..d047e8dec122 100644
--- a/libcxx/include/__concepts/semiregular.h
+++ b/libcxx/include/__concepts/semiregular.h
@@ -17,17 +17,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.object]
 
 template <class _Tp>
 concept semiregular = copyable<_Tp> && default_initializable<_Tp>;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_SEMIREGULAR_H
diff --git a/libcxx/include/__concepts/swappable.h b/libcxx/include/__concepts/swappable.h
index c691d3ab1e12..507777278161 100644
--- a/libcxx/include/__concepts/swappable.h
+++ b/libcxx/include/__concepts/swappable.h
@@ -30,10 +30,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.swappable]
 
 namespace ranges {
@@ -113,10 +113,10 @@ concept swappable_with = common_reference_with<_Tp, _Up> && requires(_Tp&& __t,
   ranges::swap(std::forward<_Up>(__u), std::forward<_Tp>(__t));
 };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___CONCEPTS_SWAPPABLE_H
diff --git a/libcxx/include/__concepts/totally_ordered.h b/libcxx/include/__concepts/totally_ordered.h
index 186c3b430dd5..fc4d564b3b4d 100644
--- a/libcxx/include/__concepts/totally_ordered.h
+++ b/libcxx/include/__concepts/totally_ordered.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [concept.totallyordered]
 
 template <class _Tp, class _Up>
@@ -52,8 +52,8 @@ concept totally_ordered_with =
     __partially_ordered_with<_Tp, _Up>;
 // clang-format on
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___CONCEPTS_TOTALLY_ORDERED_H
diff --git a/libcxx/include/__condition_variable/condition_variable.h b/libcxx/include/__condition_variable/condition_variable.h
index 3fa40287c360..e15113ced575 100644
--- a/libcxx/include/__condition_variable/condition_variable.h
+++ b/libcxx/include/__condition_variable/condition_variable.h
@@ -31,11 +31,11 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
+#if _LIBCPP_HAS_THREADS
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
-#if _LIBCPP_HAS_THREADS
-
 // enum class cv_status
 _LIBCPP_DECLARE_STRONG_ENUM(cv_status){no_timeout, timeout};
 _LIBCPP_DECLARE_STRONG_ENUM_EPILOG(cv_status)
@@ -224,11 +224,11 @@ inline void condition_variable::__do_timed_wait(unique_lock<mutex>& __lk,
   wait_for(__lk, __tp - _Clock::now());
 }
 
-#endif // _LIBCPP_HAS_THREADS
-
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_HAS_THREADS
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___CONDITION_VARIABLE_CONDITION_VARIABLE_H
diff --git a/libcxx/include/__cstddef/max_align_t.h b/libcxx/include/__cstddef/max_align_t.h
index 7c09c7e7f301..e44665ec5ebb 100644
--- a/libcxx/include/__cstddef/max_align_t.h
+++ b/libcxx/include/__cstddef/max_align_t.h
@@ -16,12 +16,14 @@
 #  pragma GCC system_header
 #endif
 
+#if !defined(_LIBCPP_CXX03_LANG)
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if !defined(_LIBCPP_CXX03_LANG)
 using ::max_align_t _LIBCPP_USING_IF_EXISTS;
-#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif
+
 #endif // _LIBCPP___CSTDDEF_MAX_ALIGN_T_H
diff --git a/libcxx/include/__format/container_adaptor.h b/libcxx/include/__format/container_adaptor.h
index 6a99a028615c..ec8b1dedb190 100644
--- a/libcxx/include/__format/container_adaptor.h
+++ b/libcxx/include/__format/container_adaptor.h
@@ -24,10 +24,10 @@
 #include <__type_traits/is_const.h>
 #include <__type_traits/maybe_const.h>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [container.adaptors.format] only specifies the library should provide the
 // formatter specializations, not which header should provide them.
 // Since <format> includes a lot of headers, add these headers here instead of
@@ -66,8 +66,8 @@ template <class _CharT, class _Tp, formattable<_CharT> _Container>
 struct formatter<stack<_Tp, _Container>, _CharT>
     : public __formatter_container_adaptor<stack<_Tp, _Container>, _CharT> {};
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___FORMAT_CONTAINER_ADAPTOR_H
diff --git a/libcxx/include/__format/enable_insertable.h b/libcxx/include/__format/enable_insertable.h
index 29fe566ff06a..d5832021aaf7 100644
--- a/libcxx/include/__format/enable_insertable.h
+++ b/libcxx/include/__format/enable_insertable.h
@@ -16,10 +16,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace __format {
 
 /// Opt-in to enable \ref __insertable for a \a _Container.
@@ -28,8 +28,8 @@ inline constexpr bool __enable_insertable = false;
 
 } // namespace __format
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___FORMAT_ENABLE_INSERTABLE_H
diff --git a/libcxx/include/__format/escaped_output_table.h b/libcxx/include/__format/escaped_output_table.h
index a62c715811a0..7b6a03162c49 100644
--- a/libcxx/include/__format/escaped_output_table.h
+++ b/libcxx/include/__format/escaped_output_table.h
@@ -71,10 +71,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace __escaped_output_table {
 // clang-format off
 
@@ -881,8 +881,8 @@ _LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __entries[735] = {
 // clang-format on
 } // namespace __escaped_output_table
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___FORMAT_ESCAPED_OUTPUT_TABLE_H
diff --git a/libcxx/include/__format/fmt_pair_like.h b/libcxx/include/__format/fmt_pair_like.h
index d2f2f54d5ac0..e7369bdf2000 100644
--- a/libcxx/include/__format/fmt_pair_like.h
+++ b/libcxx/include/__format/fmt_pair_like.h
@@ -20,10 +20,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [tuple.like] defines a tuple-like exposition only concept. This concept is not related to that. Therefore it uses a
 // different name for the concept.
 //
@@ -35,8 +35,8 @@ template <class _Tp>
 concept __fmt_pair_like =
     __is_specialization_v<_Tp, pair> || (__is_specialization_v<_Tp, tuple> && tuple_size_v<_Tp> == 2);
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___FORMAT_FMT_PAIR_LIKE_H
diff --git a/libcxx/include/__format/formatter_tuple.h b/libcxx/include/__format/formatter_tuple.h
index 0b095e6f71af..c46d02ef381e 100644
--- a/libcxx/include/__format/formatter_tuple.h
+++ b/libcxx/include/__format/formatter_tuple.h
@@ -31,10 +31,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <__fmt_char_type _CharT, class _Tuple, formattable<_CharT>... _Args>
 struct __formatter_tuple {
   _LIBCPP_HIDE_FROM_ABI constexpr void set_separator(basic_string_view<_CharT> __separator) noexcept {
@@ -141,8 +141,8 @@ struct formatter<pair<_Args...>, _CharT> : public __formatter_tuple<_CharT, pair
 template <__fmt_char_type _CharT, formattable<_CharT>... _Args>
 struct formatter<tuple<_Args...>, _CharT> : public __formatter_tuple<_CharT, tuple<_Args...>, _Args...> {};
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___FORMAT_FORMATTER_TUPLE_H
diff --git a/libcxx/include/__format/range_default_formatter.h b/libcxx/include/__format/range_default_formatter.h
index 23dfb54957b6..fbad9022821c 100644
--- a/libcxx/include/__format/range_default_formatter.h
+++ b/libcxx/include/__format/range_default_formatter.h
@@ -33,10 +33,10 @@
 #include <__utility/pair.h>
 #include <string_view>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Rp, class _CharT>
 concept __const_formattable_range =
     ranges::input_range<const _Rp> && formattable<ranges::range_reference_t<const _Rp>, _CharT>;
@@ -169,8 +169,8 @@ template <ranges::input_range _Rp, class _CharT>
   requires(format_kind<_Rp> != range_format::disabled && formattable<ranges::range_reference_t<_Rp>, _CharT>)
 struct formatter<_Rp, _CharT> : __range_default_formatter<format_kind<_Rp>, _Rp, _CharT> {};
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___FORMAT_RANGE_DEFAULT_FORMATTER_H
diff --git a/libcxx/include/__format/range_format.h b/libcxx/include/__format/range_format.h
index 0e297022cccd..8bace8ecaad8 100644
--- a/libcxx/include/__format/range_format.h
+++ b/libcxx/include/__format/range_format.h
@@ -21,10 +21,10 @@
 #include <__ranges/concepts.h>
 #include <__type_traits/remove_cvref.h>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <ranges::input_range _Rp>
   requires same_as<_Rp, remove_cvref_t<_Rp>>
 inline constexpr range_format format_kind<_Rp> = [] {
@@ -50,8 +50,8 @@ inline constexpr range_format format_kind<_Rp> = [] {
     return range_format::sequence;
 }();
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif
diff --git a/libcxx/include/__format/range_formatter.h b/libcxx/include/__format/range_formatter.h
index 4cf556b9ac82..a963a9fc704f 100644
--- a/libcxx/include/__format/range_formatter.h
+++ b/libcxx/include/__format/range_formatter.h
@@ -34,10 +34,10 @@
 #include <__type_traits/remove_cvref.h>
 #include <string_view>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp, class _CharT = char>
   requires same_as<remove_cvref_t<_Tp>, _Tp> && formattable<_Tp, _CharT>
 struct range_formatter {
@@ -260,8 +260,8 @@ private:
   basic_string_view<_CharT> __closing_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "]");
 };
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___FORMAT_RANGE_FORMATTER_H
diff --git a/libcxx/include/__functional/binary_negate.h b/libcxx/include/__functional/binary_negate.h
index 73acfb37a7ee..f7784fb1f1f1 100644
--- a/libcxx/include/__functional/binary_negate.h
+++ b/libcxx/include/__functional/binary_negate.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_NEGATORS)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Predicate>
 class _LIBCPP_DEPRECATED_IN_CXX17 binary_negate
     : public __binary_function<typename _Predicate::first_argument_type,
@@ -44,8 +44,8 @@ not2(const _Predicate& __pred) {
   return binary_negate<_Predicate>(__pred);
 }
 
-#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_NEGATORS)
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_NEGATORS)
+
 #endif // _LIBCPP___FUNCTIONAL_BINARY_NEGATE_H
diff --git a/libcxx/include/__functional/binder1st.h b/libcxx/include/__functional/binder1st.h
index 77a032245096..023c8c6b8c35 100644
--- a/libcxx/include/__functional/binder1st.h
+++ b/libcxx/include/__functional/binder1st.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Operation>
 class _LIBCPP_DEPRECATED_IN_CXX11 binder1st
     : public __unary_function<typename _Operation::second_argument_type, typename _Operation::result_type> {
@@ -47,8 +47,8 @@ bind1st(const _Operation& __op, const _Tp& __x) {
   return binder1st<_Operation>(__op, __x);
 }
 
-#endif // _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
+
 #endif // _LIBCPP___FUNCTIONAL_BINDER1ST_H
diff --git a/libcxx/include/__functional/binder2nd.h b/libcxx/include/__functional/binder2nd.h
index 8cc644151aff..e814c5dcbc70 100644
--- a/libcxx/include/__functional/binder2nd.h
+++ b/libcxx/include/__functional/binder2nd.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Operation>
 class _LIBCPP_DEPRECATED_IN_CXX11 binder2nd
     : public __unary_function<typename _Operation::first_argument_type, typename _Operation::result_type> {
@@ -47,8 +47,8 @@ bind2nd(const _Operation& __op, const _Tp& __x) {
   return binder2nd<_Operation>(__op, __x);
 }
 
-#endif // _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
+
 #endif // _LIBCPP___FUNCTIONAL_BINDER2ND_H
diff --git a/libcxx/include/__functional/compose.h b/libcxx/include/__functional/compose.h
index 4b86dd37cd48..20b30660b507 100644
--- a/libcxx/include/__functional/compose.h
+++ b/libcxx/include/__functional/compose.h
@@ -20,10 +20,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 struct __compose_op {
   template <class _Fn1, class _Fn2, class... _Args>
   _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn1&& __f1, _Fn2&& __f2, _Args&&... __args) const noexcept(noexcept(
@@ -46,8 +46,8 @@ _LIBCPP_HIDE_FROM_ABI constexpr auto __compose(_Fn1&& __f1, _Fn2&& __f2) noexcep
   return __compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(std::forward<_Fn1>(__f1), std::forward<_Fn2>(__f2));
 }
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___FUNCTIONAL_COMPOSE_H
diff --git a/libcxx/include/__functional/invoke.h b/libcxx/include/__functional/invoke.h
index ab201e94206e..f7d6a23a4e52 100644
--- a/libcxx/include/__functional/invoke.h
+++ b/libcxx/include/__functional/invoke.h
@@ -19,19 +19,17 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Fn, class... _Args>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 invoke_result_t<_Fn, _Args...>
 invoke(_Fn&& __f, _Args&&... __args) noexcept(is_nothrow_invocable_v<_Fn, _Args...>) {
   return std::__invoke(std::forward<_Fn>(__f), std::forward<_Args>(__args)...);
 }
 
-#endif // _LIBCPP_STD_VER >= 17
-
-#if _LIBCPP_STD_VER >= 23
+#  if _LIBCPP_STD_VER >= 23
 template <class _Result, class _Fn, class... _Args>
   requires is_invocable_r_v<_Result, _Fn, _Args...>
 _LIBCPP_HIDE_FROM_ABI constexpr _Result
@@ -48,8 +46,10 @@ invoke_r(_Fn&& __f, _Args&&... __args) noexcept(is_nothrow_invocable_r_v<_Result
     return std::invoke(std::forward<_Fn>(__f), std::forward<_Args>(__args)...);
   }
 }
-#endif
+#  endif
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___FUNCTIONAL_INVOKE_H
diff --git a/libcxx/include/__functional/mem_fun_ref.h b/libcxx/include/__functional/mem_fun_ref.h
index 68223772a158..bfae51454ec5 100644
--- a/libcxx/include/__functional/mem_fun_ref.h
+++ b/libcxx/include/__functional/mem_fun_ref.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Sp, class _Tp>
 class _LIBCPP_DEPRECATED_IN_CXX11 mem_fun_t : public __unary_function<_Tp*, _Sp> {
   _Sp (_Tp::*__p_)();
@@ -138,8 +138,8 @@ mem_fun_ref(_Sp (_Tp::*__f)(_Ap) const) {
   return const_mem_fun1_ref_t<_Sp, _Tp, _Ap>(__f);
 }
 
-#endif // _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
+
 #endif // _LIBCPP___FUNCTIONAL_MEM_FUN_REF_H
diff --git a/libcxx/include/__functional/perfect_forward.h b/libcxx/include/__functional/perfect_forward.h
index 37c3d15b4bec..c0408b410e2f 100644
--- a/libcxx/include/__functional/perfect_forward.h
+++ b/libcxx/include/__functional/perfect_forward.h
@@ -28,10 +28,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Op, class _Indices, class... _BoundArgs>
 struct __perfect_forward_impl;
 
@@ -96,10 +96,10 @@ public:
 template <class _Op, class... _Args>
 using __perfect_forward _LIBCPP_NODEBUG = __perfect_forward_impl<_Op, index_sequence_for<_Args...>, _Args...>;
 
-#endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___FUNCTIONAL_PERFECT_FORWARD_H
diff --git a/libcxx/include/__functional/pointer_to_binary_function.h b/libcxx/include/__functional/pointer_to_binary_function.h
index eb0e7674eea9..89e0fa5fe2ac 100644
--- a/libcxx/include/__functional/pointer_to_binary_function.h
+++ b/libcxx/include/__functional/pointer_to_binary_function.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Arg1, class _Arg2, class _Result>
 class _LIBCPP_DEPRECATED_IN_CXX11 pointer_to_binary_function : public __binary_function<_Arg1, _Arg2, _Result> {
   _Result (*__f_)(_Arg1, _Arg2);
@@ -36,8 +36,8 @@ ptr_fun(_Result (*__f)(_Arg1, _Arg2)) {
   return pointer_to_binary_function<_Arg1, _Arg2, _Result>(__f);
 }
 
-#endif
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif
+
 #endif // _LIBCPP___FUNCTIONAL_POINTER_TO_BINARY_FUNCTION_H
diff --git a/libcxx/include/__functional/pointer_to_unary_function.h b/libcxx/include/__functional/pointer_to_unary_function.h
index 459d24abdd7e..b7778e4502db 100644
--- a/libcxx/include/__functional/pointer_to_unary_function.h
+++ b/libcxx/include/__functional/pointer_to_unary_function.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Arg, class _Result>
 class _LIBCPP_DEPRECATED_IN_CXX11 pointer_to_unary_function : public __unary_function<_Arg, _Result> {
   _Result (*__f_)(_Arg);
@@ -36,8 +36,8 @@ ptr_fun(_Result (*__f)(_Arg)) {
   return pointer_to_unary_function<_Arg, _Result>(__f);
 }
 
-#endif // _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_BINDERS)
+
 #endif // _LIBCPP___FUNCTIONAL_POINTER_TO_UNARY_FUNCTION_H
diff --git a/libcxx/include/__functional/ranges_operations.h b/libcxx/include/__functional/ranges_operations.h
index dc9da061af26..66fe053b1563 100644
--- a/libcxx/include/__functional/ranges_operations.h
+++ b/libcxx/include/__functional/ranges_operations.h
@@ -21,10 +21,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 struct equal_to {
@@ -115,8 +115,8 @@ inline const bool __is_generic_transparent_comparator_v<ranges::less> = true;
 template <>
 inline const bool __is_generic_transparent_comparator_v<ranges::greater> = true;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___FUNCTIONAL_RANGES_OPERATIONS_H
diff --git a/libcxx/include/__functional/unary_negate.h b/libcxx/include/__functional/unary_negate.h
index a93abc8e6b1c..761f0be5f856 100644
--- a/libcxx/include/__functional/unary_negate.h
+++ b/libcxx/include/__functional/unary_negate.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_NEGATORS)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Predicate>
 class _LIBCPP_DEPRECATED_IN_CXX17 unary_negate : public __unary_function<typename _Predicate::argument_type, bool> {
   _Predicate __pred_;
@@ -40,8 +40,8 @@ not1(const _Predicate& __pred) {
   return unary_negate<_Predicate>(__pred);
 }
 
-#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_NEGATORS)
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_NEGATORS)
+
 #endif // _LIBCPP___FUNCTIONAL_UNARY_NEGATE_H
diff --git a/libcxx/include/__fwd/format.h b/libcxx/include/__fwd/format.h
index e9d15360f12e..dd3260e36f4e 100644
--- a/libcxx/include/__fwd/format.h
+++ b/libcxx/include/__fwd/format.h
@@ -16,10 +16,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Context>
 class basic_format_arg;
 
@@ -48,8 +48,8 @@ constexpr range_format format_kind = [] {
 
 #  endif // _LIBCPP_STD_VER >= 23
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___FWD_FORMAT_H
diff --git a/libcxx/include/__fwd/span.h b/libcxx/include/__fwd/span.h
index 5d473ee51c6b..8610915edd02 100644
--- a/libcxx/include/__fwd/span.h
+++ b/libcxx/include/__fwd/span.h
@@ -21,18 +21,18 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max();
 template <typename _Tp, size_t _Extent = dynamic_extent>
 class span;
 
-#endif
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___FWD_SPAN_H
diff --git a/libcxx/include/__fwd/variant.h b/libcxx/include/__fwd/variant.h
index fef7071b3264..a484248fe542 100644
--- a/libcxx/include/__fwd/variant.h
+++ b/libcxx/include/__fwd/variant.h
@@ -16,10 +16,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class... _Types>
 class variant;
 
@@ -61,8 +61,8 @@ _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& get(const variant<_Types...>&);
 template <class _Tp, class... _Types>
 _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&& get(const variant<_Types...>&&);
 
-#endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___FWD_VARIANT_H
diff --git a/libcxx/include/__iterator/data.h b/libcxx/include/__iterator/data.h
index d1f32a795b70..7efa57e1a22a 100644
--- a/libcxx/include/__iterator/data.h
+++ b/libcxx/include/__iterator/data.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Cont>
 [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI auto data(_Cont& __c) noexcept(noexcept(__c.data()))
     -> decltype(__c.data()) {
@@ -43,8 +43,8 @@ template <class _Ep>
   return __il.begin();
 }
 
-#endif
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___ITERATOR_DATA_H
diff --git a/libcxx/include/__iterator/default_sentinel.h b/libcxx/include/__iterator/default_sentinel.h
index 3b65f442f1a8..84fcf71c0767 100644
--- a/libcxx/include/__iterator/default_sentinel.h
+++ b/libcxx/include/__iterator/default_sentinel.h
@@ -16,15 +16,15 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 struct default_sentinel_t {};
 inline constexpr default_sentinel_t default_sentinel{};
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___ITERATOR_DEFAULT_SENTINEL_H
diff --git a/libcxx/include/__iterator/empty.h b/libcxx/include/__iterator/empty.h
index f2c653bcb329..b763048f547e 100644
--- a/libcxx/include/__iterator/empty.h
+++ b/libcxx/include/__iterator/empty.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Cont>
 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto
 empty(const _Cont& __c) noexcept(noexcept(__c.empty())) -> decltype(__c.empty()) {
@@ -37,8 +37,8 @@ template <class _Ep>
   return __il.size() == 0;
 }
 
-#endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___ITERATOR_EMPTY_H
diff --git a/libcxx/include/__iterator/incrementable_traits.h b/libcxx/include/__iterator/incrementable_traits.h
index dc62b1abb397..692ce76285f6 100644
--- a/libcxx/include/__iterator/incrementable_traits.h
+++ b/libcxx/include/__iterator/incrementable_traits.h
@@ -24,10 +24,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [incrementable.traits]
 template <class>
 struct incrementable_traits {};
@@ -72,8 +72,8 @@ using iter_difference_t =
                            incrementable_traits<remove_cvref_t<_Ip> >,
                            iterator_traits<remove_cvref_t<_Ip> > >::difference_type;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___ITERATOR_INCREMENTABLE_TRAITS_H
diff --git a/libcxx/include/__iterator/iter_move.h b/libcxx/include/__iterator/iter_move.h
index 91f8332a88e3..b371f09fe111 100644
--- a/libcxx/include/__iterator/iter_move.h
+++ b/libcxx/include/__iterator/iter_move.h
@@ -27,10 +27,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [iterator.cust.move]
 
 namespace ranges {
@@ -95,10 +95,10 @@ template <__dereferenceable _Tp>
   }
 using iter_rvalue_reference_t = decltype(ranges::iter_move(std::declval<_Tp&>()));
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___ITERATOR_ITER_MOVE_H
diff --git a/libcxx/include/__iterator/iter_swap.h b/libcxx/include/__iterator/iter_swap.h
index 01ab1b97d650..f4a5744a7edd 100644
--- a/libcxx/include/__iterator/iter_swap.h
+++ b/libcxx/include/__iterator/iter_swap.h
@@ -29,10 +29,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [iter.cust.swap]
 
 namespace ranges {
@@ -99,10 +99,10 @@ concept indirectly_swappable =
       ranges::iter_swap(__i2, __i1);
     };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___ITERATOR_ITER_SWAP_H
diff --git a/libcxx/include/__iterator/move_sentinel.h b/libcxx/include/__iterator/move_sentinel.h
index b3d14ee3fdf6..876b2b24507c 100644
--- a/libcxx/include/__iterator/move_sentinel.h
+++ b/libcxx/include/__iterator/move_sentinel.h
@@ -22,10 +22,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <semiregular _Sent>
 class move_sentinel {
 public:
@@ -52,10 +52,10 @@ private:
 
 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(move_sentinel);
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___ITERATOR_MOVE_SENTINEL_H
diff --git a/libcxx/include/__iterator/ranges_iterator_traits.h b/libcxx/include/__iterator/ranges_iterator_traits.h
index 9a31b651eb5d..b92f45f7a875 100644
--- a/libcxx/include/__iterator/ranges_iterator_traits.h
+++ b/libcxx/include/__iterator/ranges_iterator_traits.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <ranges::input_range _Range>
 using __range_key_type _LIBCPP_NODEBUG = __remove_const_t<typename ranges::range_value_t<_Range>::first_type>;
 
@@ -33,8 +33,8 @@ template <ranges::input_range _Range>
 using __range_to_alloc_type _LIBCPP_NODEBUG =
     pair<const typename ranges::range_value_t<_Range>::first_type, typename ranges::range_value_t<_Range>::second_type>;
 
-#endif
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif
+
 #endif // _LIBCPP___ITERATOR_RANGES_ITERATOR_TRAITS_H
diff --git a/libcxx/include/__iterator/readable_traits.h b/libcxx/include/__iterator/readable_traits.h
index 05c24d828937..ed169c46351b 100644
--- a/libcxx/include/__iterator/readable_traits.h
+++ b/libcxx/include/__iterator/readable_traits.h
@@ -24,10 +24,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [readable.traits]
 template <class>
 struct __cond_value_type {};
@@ -74,8 +74,8 @@ template <__has_member_value_type _Tp>
            same_as<remove_cv_t<typename _Tp::element_type>, remove_cv_t<typename _Tp::value_type>>
 struct indirectly_readable_traits<_Tp> : __cond_value_type<typename _Tp::value_type> {};
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___ITERATOR_READABLE_TRAITS_H
diff --git a/libcxx/include/__iterator/reverse_access.h b/libcxx/include/__iterator/reverse_access.h
index cd4e42a32827..b1574bc66511 100644
--- a/libcxx/include/__iterator/reverse_access.h
+++ b/libcxx/include/__iterator/reverse_access.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 14
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp, size_t _Np>
 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
 _LIBCPP_CONSTEXPR_SINCE_CXX17 reverse_iterator<_Tp*> rbegin(_Tp (&__array)[_Np]) {
@@ -79,8 +79,8 @@ template <class _Cp>
   return std::rend(__c);
 }
 
-#endif // _LIBCPP_STD_VER >= 14
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 14
+
 #endif // _LIBCPP___ITERATOR_REVERSE_ACCESS_H
diff --git a/libcxx/include/__iterator/size.h b/libcxx/include/__iterator/size.h
index e9a0f7627c0f..eb441e25b019 100644
--- a/libcxx/include/__iterator/size.h
+++ b/libcxx/include/__iterator/size.h
@@ -20,10 +20,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Cont>
 [[nodiscard]]
 _LIBCPP_HIDE_FROM_ABI constexpr auto size(const _Cont& __c) noexcept(noexcept(__c.size())) -> decltype(__c.size()) {
@@ -54,8 +54,8 @@ template <class _Tp, ptrdiff_t _Sz>
 _LIBCPP_DIAGNOSTIC_POP
 #  endif
 
-#endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___ITERATOR_SIZE_H
diff --git a/libcxx/include/__math/special_functions.h b/libcxx/include/__math/special_functions.h
index 6b217852e2f8..64d16aa88d2e 100644
--- a/libcxx/include/__math/special_functions.h
+++ b/libcxx/include/__math/special_functions.h
@@ -21,10 +21,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Real>
 _LIBCPP_HIDE_FROM_ABI _Real __hermite(unsigned __n, _Real __x) {
   // The Hermite polynomial H_n(x).
@@ -77,8 +77,8 @@ _LIBCPP_HIDE_FROM_ABI double hermite(unsigned __n, _Integer __x) {
   return std::hermite(__n, static_cast<double>(__x));
 }
 
-#endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___MATH_SPECIAL_FUNCTIONS_H
diff --git a/libcxx/include/__mdspan/aligned_accessor.h b/libcxx/include/__mdspan/aligned_accessor.h
index 2b8d4c52d873..934b0d42abe4 100644
--- a/libcxx/include/__mdspan/aligned_accessor.h
+++ b/libcxx/include/__mdspan/aligned_accessor.h
@@ -33,10 +33,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 26
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _ElementType, size_t _ByteAlignment>
 struct aligned_accessor {
   static_assert(_ByteAlignment != 0 && (_ByteAlignment & (_ByteAlignment - 1)) == 0,
@@ -78,10 +78,10 @@ struct aligned_accessor {
   }
 };
 
-#endif // _LIBCPP_STD_VER >= 26
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 26
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___MDSPAN_ALIGNED_ACCESSOR_H
diff --git a/libcxx/include/__memory/compressed_pair.h b/libcxx/include/__memory/compressed_pair.h
index bb745620b9f8..8fa0e64714f2 100644
--- a/libcxx/include/__memory/compressed_pair.h
+++ b/libcxx/include/__memory/compressed_pair.h
@@ -20,8 +20,6 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 // ================================================================================================================== //
 // The utilites here are for staying ABI compatible with the legacy `__compressed_pair`. They should not be used      //
 // for new data structures. Use `_LIBCPP_NO_UNIQUE_ADDRESS` for new data structures instead (but make sure you        //
@@ -59,6 +57,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 #ifndef _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp>
 inline const size_t __compressed_pair_alignment = _LIBCPP_ALIGNOF(_Tp);
 
@@ -104,6 +104,8 @@ class __compressed_pair_padding<_ToPad, true> {};
       }
 #  endif
 
+_LIBCPP_END_NAMESPACE_STD
+
 #else
 #  define _LIBCPP_COMPRESSED_ELEMENT(T1, Initializer1) _LIBCPP_NO_UNIQUE_ADDRESS T1 Initializer1
 
@@ -112,6 +114,4 @@ class __compressed_pair_padding<_ToPad, true> {};
     _LIBCPP_NO_UNIQUE_ADDRESS T2 Name2
 #endif // _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING
 
-_LIBCPP_END_NAMESPACE_STD
-
 #endif // _LIBCPP___MEMORY_COMPRESSED_PAIR_H
diff --git a/libcxx/include/__memory/inout_ptr.h b/libcxx/include/__memory/inout_ptr.h
index f0335cf855fc..f654b44e03f6 100644
--- a/libcxx/include/__memory/inout_ptr.h
+++ b/libcxx/include/__memory/inout_ptr.h
@@ -29,10 +29,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Smart, class _Pointer, class... _Args>
 class inout_ptr_t {
   static_assert(!__is_specialization_v<_Smart, shared_ptr>, "std::shared_ptr<> is not supported with std::inout_ptr.");
@@ -100,10 +100,10 @@ template <class _Pointer = void, class _Smart, class... _Args>
   return std::inout_ptr_t<_Smart, _Ptr, _Args&&...>(__s, std::forward<_Args>(__args)...);
 }
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___INOUT_PTR_H
diff --git a/libcxx/include/__memory/out_ptr.h b/libcxx/include/__memory/out_ptr.h
index 806c863daeea..12960b76717d 100644
--- a/libcxx/include/__memory/out_ptr.h
+++ b/libcxx/include/__memory/out_ptr.h
@@ -28,10 +28,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Smart, class _Pointer, class... _Args>
 class out_ptr_t {
   static_assert(!__is_specialization_v<_Smart, shared_ptr> || sizeof...(_Args) > 0,
@@ -92,10 +92,10 @@ template <class _Pointer = void, class _Smart, class... _Args>
   return std::out_ptr_t<_Smart, _Ptr, _Args&&...>(__s, std::forward<_Args>(__args)...);
 }
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___OUT_PTR_H
diff --git a/libcxx/include/__memory/raw_storage_iterator.h b/libcxx/include/__memory/raw_storage_iterator.h
index dff0fed3b756..a813d4a67835 100644
--- a/libcxx/include/__memory/raw_storage_iterator.h
+++ b/libcxx/include/__memory/raw_storage_iterator.h
@@ -21,13 +21,13 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_RAW_STORAGE_ITERATOR)
+
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_RAW_STORAGE_ITERATOR)
-
 template <class _OutputIterator, class _Tp>
 class _LIBCPP_DEPRECATED_IN_CXX17 raw_storage_iterator
     : public __iterator_base<raw_storage_iterator<_OutputIterator, _Tp>, output_iterator_tag, void, void, void, void> {
@@ -71,10 +71,10 @@ public:
 #  endif
 };
 
-#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_RAW_STORAGE_ITERATOR)
-
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
+#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_RAW_STORAGE_ITERATOR)
+
 #endif // _LIBCPP___MEMORY_RAW_STORAGE_ITERATOR_H
diff --git a/libcxx/include/__memory/uses_allocator_construction.h b/libcxx/include/__memory/uses_allocator_construction.h
index 6733f5cf6fc3..e9653f6c4ea5 100644
--- a/libcxx/include/__memory/uses_allocator_construction.h
+++ b/libcxx/include/__memory/uses_allocator_construction.h
@@ -27,10 +27,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp>
 inline constexpr bool __is_cv_std_pair = __is_pair_v<remove_cv_t<_Tp>>;
 
@@ -202,9 +202,7 @@ __uninitialized_construct_using_allocator(_Type* __ptr, const _Alloc& __alloc, _
       __uses_allocator_construction_args<_Type>::__apply(__alloc, std::forward<_Args>(__args)...));
 }
 
-#endif // _LIBCPP_STD_VER >= 17
-
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
 
 template <class _Type, class _Alloc, class... _Args>
 _LIBCPP_HIDE_FROM_ABI constexpr auto uses_allocator_construction_args(const _Alloc& __alloc, _Args&&... __args) noexcept
@@ -225,10 +223,12 @@ uninitialized_construct_using_allocator(_Type* __ptr, const _Alloc& __alloc, _Ar
   return /*--*/ std::__uninitialized_construct_using_allocator(__ptr, __alloc, std::forward<_Args>(__args)...);
 }
 
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___MEMORY_USES_ALLOCATOR_CONSTRUCTION_H
diff --git a/libcxx/include/__node_handle b/libcxx/include/__node_handle
index 789f2b5f9a52..bc515955aa07 100644
--- a/libcxx/include/__node_handle
+++ b/libcxx/include/__node_handle
@@ -73,10 +73,10 @@ public:
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // Specialized in __tree & __hash_table for their _NodeType.
 template <class _NodeType, class _Alloc>
 struct __generic_container_node_destructor;
@@ -200,10 +200,10 @@ struct __insert_return_type {
   _NodeType node;
 };
 
-#endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___NODE_HANDLE
diff --git a/libcxx/include/__numeric/ranges_iota.h b/libcxx/include/__numeric/ranges_iota.h
index bf53dd85fece..c67e6e92826a 100644
--- a/libcxx/include/__numeric/ranges_iota.h
+++ b/libcxx/include/__numeric/ranges_iota.h
@@ -26,9 +26,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
+#if _LIBCPP_STD_VER >= 23
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 23
 namespace ranges {
 template <typename _Out, typename _Tp>
 using iota_result = ranges::out_value_result<_Out, _Tp>;
@@ -56,10 +57,10 @@ public:
 inline constexpr auto iota = __iota_fn{};
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___NUMERIC_RANGES_IOTA_H
diff --git a/libcxx/include/__numeric/reduce.h b/libcxx/include/__numeric/reduce.h
index a3bfab1fc094..853ca6fb6186 100644
--- a/libcxx/include/__numeric/reduce.h
+++ b/libcxx/include/__numeric/reduce.h
@@ -22,9 +22,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
+#if _LIBCPP_STD_VER >= 17
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 17
 template <class _InputIterator, class _Tp, class _BinaryOp>
 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
 _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp reduce(_InputIterator __first, _InputIterator __last, _Tp __init, _BinaryOp __b) {
@@ -44,10 +45,11 @@ template <class _InputIterator>
 reduce(_InputIterator __first, _InputIterator __last) {
   return std::reduce(__first, __last, typename iterator_traits<_InputIterator>::value_type{});
 }
-#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___NUMERIC_REDUCE_H
diff --git a/libcxx/include/__numeric/transform_reduce.h b/libcxx/include/__numeric/transform_reduce.h
index 382c314ca498..53ed6aaf32d1 100644
--- a/libcxx/include/__numeric/transform_reduce.h
+++ b/libcxx/include/__numeric/transform_reduce.h
@@ -21,9 +21,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
+#if _LIBCPP_STD_VER >= 17
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 17
 template <class _InputIterator, class _Tp, class _BinaryOp, class _UnaryOp>
 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
 _Tp transform_reduce(_InputIterator __first, _InputIterator __last, _Tp __init, _BinaryOp __b, _UnaryOp __u) {
@@ -50,10 +51,11 @@ template <class _InputIterator1, class _InputIterator2, class _Tp>
 transform_reduce(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _Tp __init) {
   return std::transform_reduce(__first1, __last1, __first2, std::move(__init), std::plus<>(), std::multiplies<>());
 }
-#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___NUMERIC_TRANSFORM_REDUCE_H
diff --git a/libcxx/include/__random/random_device.h b/libcxx/include/__random/random_device.h
index 9da0b6172c9f..f28e5fca140e 100644
--- a/libcxx/include/__random/random_device.h
+++ b/libcxx/include/__random/random_device.h
@@ -19,11 +19,11 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
+#if _LIBCPP_HAS_RANDOM_DEVICE
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
-#if _LIBCPP_HAS_RANDOM_DEVICE
-
 class _LIBCPP_EXPORTED_FROM_ABI random_device {
 #  ifdef _LIBCPP_USING_DEV_RANDOM
   int __f_;
@@ -69,11 +69,11 @@ public:
   void operator=(const random_device&) = delete;
 };
 
-#endif // _LIBCPP_HAS_RANDOM_DEVICE
-
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_HAS_RANDOM_DEVICE
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___RANDOM_RANDOM_DEVICE_H
diff --git a/libcxx/include/__random/uniform_random_bit_generator.h b/libcxx/include/__random/uniform_random_bit_generator.h
index 75ffc27f9fcd..738a293f1e7e 100644
--- a/libcxx/include/__random/uniform_random_bit_generator.h
+++ b/libcxx/include/__random/uniform_random_bit_generator.h
@@ -23,10 +23,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [rand.req.urng]
 template <class _Gen>
 concept uniform_random_bit_generator = invocable<_Gen&> && unsigned_integral<invoke_result_t<_Gen&>> && requires {
@@ -35,10 +35,10 @@ concept uniform_random_bit_generator = invocable<_Gen&> && unsigned_integral<inv
   requires bool_constant<(_Gen::min() < _Gen::max())>::value;
 };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___RANDOM_UNIFORM_RANDOM_BIT_GENERATOR_H
diff --git a/libcxx/include/__ranges/access.h b/libcxx/include/__ranges/access.h
index bbacef3eae6b..28555ef6ba0d 100644
--- a/libcxx/include/__ranges/access.h
+++ b/libcxx/include/__ranges/access.h
@@ -27,10 +27,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 template <class _Tp>
 concept __can_borrow = is_lvalue_reference_v<_Tp> || enable_borrowed_range<remove_cvref_t<_Tp>>;
@@ -203,8 +203,8 @@ inline constexpr auto cend = __cend::__fn{};
 } // namespace __cpo
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_ACCESS_H
diff --git a/libcxx/include/__ranges/all.h b/libcxx/include/__ranges/all.h
index 023cee6caa9a..5ee9901cb158 100644
--- a/libcxx/include/__ranges/all.h
+++ b/libcxx/include/__ranges/all.h
@@ -29,10 +29,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges::views {
 
 namespace __all {
@@ -71,8 +71,8 @@ using all_t = decltype(views::all(std::declval<_Range>()));
 
 } // namespace ranges::views
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_ALL_H
diff --git a/libcxx/include/__ranges/concepts.h b/libcxx/include/__ranges/concepts.h
index bf75fe8a6fef..e1c855860c50 100644
--- a/libcxx/include/__ranges/concepts.h
+++ b/libcxx/include/__ranges/concepts.h
@@ -39,10 +39,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 // [range.range]
@@ -175,8 +175,8 @@ concept __concatable = requires {
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_CONCEPTS_H
diff --git a/libcxx/include/__ranges/container_compatible_range.h b/libcxx/include/__ranges/container_compatible_range.h
index a58f1119885e..ecf46f49232a 100644
--- a/libcxx/include/__ranges/container_compatible_range.h
+++ b/libcxx/include/__ranges/container_compatible_range.h
@@ -18,16 +18,16 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Range, class _Tp>
 concept _ContainerCompatibleRange =
     ranges::input_range<_Range> && convertible_to<ranges::range_reference_t<_Range>, _Tp>;
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___RANGES_CONTAINER_COMPATIBLE_RANGE_H
diff --git a/libcxx/include/__ranges/dangling.h b/libcxx/include/__ranges/dangling.h
index 613084d5fb9f..fdd41351add4 100644
--- a/libcxx/include/__ranges/dangling.h
+++ b/libcxx/include/__ranges/dangling.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 struct dangling {
   dangling() = default;
@@ -35,8 +35,8 @@ using borrowed_iterator_t = _If<borrowed_range<_Rp>, iterator_t<_Rp>, dangling>;
 // borrowed_subrange_t defined in <__ranges/subrange.h>
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_DANGLING_H
diff --git a/libcxx/include/__ranges/data.h b/libcxx/include/__ranges/data.h
index cb3b826fceb2..354a0aa15903 100644
--- a/libcxx/include/__ranges/data.h
+++ b/libcxx/include/__ranges/data.h
@@ -28,10 +28,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [range.prim.data]
 
 namespace ranges {
@@ -95,8 +95,8 @@ inline constexpr auto cdata = __cdata::__fn{};
 } // namespace __cpo
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_DATA_H
diff --git a/libcxx/include/__ranges/elements_of.h b/libcxx/include/__ranges/elements_of.h
index 3f89f49d182a..de6aa786e6b1 100644
--- a/libcxx/include/__ranges/elements_of.h
+++ b/libcxx/include/__ranges/elements_of.h
@@ -23,10 +23,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 template <range _Range, class _Allocator = allocator<byte>>
@@ -40,10 +40,10 @@ elements_of(_Range&&, _Allocator = _Allocator()) -> elements_of<_Range&&, _Alloc
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___RANGES_ELEMENTS_OF_H
diff --git a/libcxx/include/__ranges/empty.h b/libcxx/include/__ranges/empty.h
index 5c1004042aba..f2f12329d224 100644
--- a/libcxx/include/__ranges/empty.h
+++ b/libcxx/include/__ranges/empty.h
@@ -20,10 +20,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [range.prim.empty]
 
 namespace ranges {
@@ -64,8 +64,8 @@ inline constexpr auto empty = __empty::__fn{};
 } // namespace __cpo
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_EMPTY_H
diff --git a/libcxx/include/__ranges/enable_borrowed_range.h b/libcxx/include/__ranges/enable_borrowed_range.h
index 1d068335e20a..70eb4e87c8a6 100644
--- a/libcxx/include/__ranges/enable_borrowed_range.h
+++ b/libcxx/include/__ranges/enable_borrowed_range.h
@@ -20,10 +20,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 // [range.range], ranges
@@ -33,8 +33,8 @@ inline constexpr bool enable_borrowed_range = false;
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_ENABLE_BORROWED_RANGE_H
diff --git a/libcxx/include/__ranges/enable_view.h b/libcxx/include/__ranges/enable_view.h
index 6dee6ea3fa3d..2c58cb6293d2 100644
--- a/libcxx/include/__ranges/enable_view.h
+++ b/libcxx/include/__ranges/enable_view.h
@@ -20,10 +20,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 struct view_base {};
@@ -43,8 +43,8 @@ inline constexpr bool enable_view = derived_from<_Tp, view_base> || requires {
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_ENABLE_VIEW_H
diff --git a/libcxx/include/__ranges/from_range.h b/libcxx/include/__ranges/from_range.h
index a6cb9e3d439e..c02bddc3d9f9 100644
--- a/libcxx/include/__ranges/from_range.h
+++ b/libcxx/include/__ranges/from_range.h
@@ -16,18 +16,18 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 struct from_range_t {
   explicit from_range_t() = default;
 };
 
 inline constexpr from_range_t from_range{};
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___RANGES_FROM_RANGE_H
diff --git a/libcxx/include/__ranges/owning_view.h b/libcxx/include/__ranges/owning_view.h
index 1ab81afee774..cb6ea660551a 100644
--- a/libcxx/include/__ranges/owning_view.h
+++ b/libcxx/include/__ranges/owning_view.h
@@ -30,10 +30,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 template <range _Rp>
   requires movable<_Rp> && (!__is_std_initializer_list<remove_cvref_t<_Rp>>)
@@ -107,10 +107,10 @@ inline constexpr bool enable_borrowed_range<owning_view<_Tp>> = enable_borrowed_
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___RANGES_OWNING_VIEW_H
diff --git a/libcxx/include/__ranges/range_adaptor.h b/libcxx/include/__ranges/range_adaptor.h
index 4bcb53e1a584..6aac4f15f750 100644
--- a/libcxx/include/__ranges/range_adaptor.h
+++ b/libcxx/include/__ranges/range_adaptor.h
@@ -34,10 +34,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 // CRTP base that one can derive from in order to be considered a range adaptor closure
@@ -90,10 +90,10 @@ class _LIBCPP_NO_SPECIALIZATIONS range_adaptor_closure : public __range_adaptor_
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___RANGES_RANGE_ADAPTOR_H
diff --git a/libcxx/include/__ranges/ref_view.h b/libcxx/include/__ranges/ref_view.h
index 109a10cec299..ea7e9cb3b6da 100644
--- a/libcxx/include/__ranges/ref_view.h
+++ b/libcxx/include/__ranges/ref_view.h
@@ -32,10 +32,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 template <range _Range>
   requires is_object_v<_Range>
@@ -82,8 +82,8 @@ template <class _Tp>
 inline constexpr bool enable_borrowed_range<ref_view<_Tp>> = true;
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_REF_VIEW_H
diff --git a/libcxx/include/__ranges/repeat_view.h b/libcxx/include/__ranges/repeat_view.h
index 9192183f4801..ae13af8761b8 100644
--- a/libcxx/include/__ranges/repeat_view.h
+++ b/libcxx/include/__ranges/repeat_view.h
@@ -40,10 +40,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 template <class _Tp>
@@ -265,10 +265,10 @@ inline constexpr bool __is_repeat_specialization<repeat_view<_Tp, _Bound>> = tru
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___RANGES_REPEAT_VIEW_H
diff --git a/libcxx/include/__ranges/size.h b/libcxx/include/__ranges/size.h
index 5da3a6ff268e..2697560ccbfa 100644
--- a/libcxx/include/__ranges/size.h
+++ b/libcxx/include/__ranges/size.h
@@ -29,10 +29,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 template <class>
 inline constexpr bool disable_sized_range = false;
@@ -131,8 +131,8 @@ inline constexpr auto ssize = __ssize::__fn{};
 } // namespace __cpo
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_SIZE_H
diff --git a/libcxx/include/__ranges/subrange.h b/libcxx/include/__ranges/subrange.h
index 3d94b0a72b96..41ab267417e9 100644
--- a/libcxx/include/__ranges/subrange.h
+++ b/libcxx/include/__ranges/subrange.h
@@ -49,10 +49,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 template <class _From, class _To>
 concept __uses_nonqualification_pointer_conversion =
@@ -266,10 +266,10 @@ struct tuple_element<1, const ranges::subrange<_Ip, _Sp, _Kp>> {
   using type _LIBCPP_NODEBUG = _Sp;
 };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___RANGES_SUBRANGE_H
diff --git a/libcxx/include/__ranges/view_interface.h b/libcxx/include/__ranges/view_interface.h
index 37b2c9e2c1a7..96508c2be727 100644
--- a/libcxx/include/__ranges/view_interface.h
+++ b/libcxx/include/__ranges/view_interface.h
@@ -30,10 +30,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace ranges {
 
 template <class _Derived>
@@ -163,8 +163,8 @@ public:
 
 } // namespace ranges
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___RANGES_VIEW_INTERFACE_H
diff --git a/libcxx/include/__ranges/views.h b/libcxx/include/__ranges/views.h
index a4de2a5e52a9..e416b3f76d3f 100644
--- a/libcxx/include/__ranges/views.h
+++ b/libcxx/include/__ranges/views.h
@@ -22,7 +22,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace ranges {
 
-namespace views {}
+namespace views { // NOLINT(libcpp-avoid-empty-namespaces) // This is needed to declare the alias below.
+} // namespace views
 
 } // namespace ranges
 
diff --git a/libcxx/include/__stop_token/atomic_unique_lock.h b/libcxx/include/__stop_token/atomic_unique_lock.h
index 79baa3b40846..99f94b8a7893 100644
--- a/libcxx/include/__stop_token/atomic_unique_lock.h
+++ b/libcxx/include/__stop_token/atomic_unique_lock.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // This class implements an RAII unique_lock without a mutex.
 // It uses std::atomic<State>,
 // where State contains a lock bit and might contain other data,
@@ -134,8 +134,8 @@ private:
   _LIBCPP_HIDE_FROM_ABI static constexpr auto __set_locked_bit = [](_State __state) { return __state | _LockedBit; };
 };
 
-#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___STOP_TOKEN_ATOMIC_UNIQUE_LOCK_H
diff --git a/libcxx/include/__stop_token/intrusive_list_view.h b/libcxx/include/__stop_token/intrusive_list_view.h
index 11a3e267e7c6..0198b1756a52 100644
--- a/libcxx/include/__stop_token/intrusive_list_view.h
+++ b/libcxx/include/__stop_token/intrusive_list_view.h
@@ -17,10 +17,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Derived>
 struct __intrusive_node_base {
   _Derived* __next_ = nullptr;
@@ -78,8 +78,8 @@ private:
   _Node* __head_ = nullptr;
 };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___STOP_TOKEN_INTRUSIVE_LIST_VIEW_H
diff --git a/libcxx/include/__stop_token/intrusive_shared_ptr.h b/libcxx/include/__stop_token/intrusive_shared_ptr.h
index 05fe9b8acb6d..c37317f8c5c7 100644
--- a/libcxx/include/__stop_token/intrusive_shared_ptr.h
+++ b/libcxx/include/__stop_token/intrusive_shared_ptr.h
@@ -25,10 +25,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // For intrusive_shared_ptr to work with a type T, specialize __intrusive_shared_ptr_traits<T> and implement
 // the following function:
 //
@@ -125,10 +125,10 @@ private:
   }
 };
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___STOP_TOKEN_INTRUSIVE_SHARED_PTR_H
diff --git a/libcxx/include/__stop_token/stop_callback.h b/libcxx/include/__stop_token/stop_callback.h
index 76d438e096c0..f9d486b34746 100644
--- a/libcxx/include/__stop_token/stop_callback.h
+++ b/libcxx/include/__stop_token/stop_callback.h
@@ -29,10 +29,10 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Callback>
 class stop_callback : private __stop_callback_base {
   static_assert(invocable<_Callback>,
@@ -93,10 +93,10 @@ private:
 template <class _Callback>
 stop_callback(stop_token, _Callback) -> stop_callback<_Callback>;
 
-#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
+
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___STOP_TOKEN_STOP_CALLBACK_H
diff --git a/libcxx/include/__stop_token/stop_state.h b/libcxx/include/__stop_token/stop_state.h
index 7f76392bd014..762cf203b0af 100644
--- a/libcxx/include/__stop_token/stop_state.h
+++ b/libcxx/include/__stop_token/stop_state.h
@@ -23,10 +23,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 struct __stop_callback_base : __intrusive_node_base<__stop_callback_base> {
   using __callback_fn_t _LIBCPP_NODEBUG = void(__stop_callback_base*) noexcept;
   _LIBCPP_HIDE_FROM_ABI explicit __stop_callback_base(__callback_fn_t* __callback_fn) : __callback_fn_(__callback_fn) {}
@@ -230,8 +230,8 @@ struct __intrusive_shared_ptr_traits<__stop_state> {
   }
 };
 
-#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
+
 #endif // _LIBCPP___STOP_TOKEN_STOP_STATE_H
diff --git a/libcxx/include/__stop_token/stop_token.h b/libcxx/include/__stop_token/stop_token.h
index 4a6ca27ac44d..c6658f86879d 100644
--- a/libcxx/include/__stop_token/stop_token.h
+++ b/libcxx/include/__stop_token/stop_token.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 class stop_token {
 public:
   _LIBCPP_HIDE_FROM_ABI stop_token() noexcept = default;
@@ -56,8 +56,8 @@ private:
   _LIBCPP_HIDE_FROM_ABI explicit stop_token(const __intrusive_shared_ptr<__stop_state>& __state) : __state_(__state) {}
 };
 
-#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
+
 #endif // _LIBCPP___STOP_TOKEN_STOP_TOKEN_H
diff --git a/libcxx/include/__thread/id.h b/libcxx/include/__thread/id.h
index 14a51fc9ee88..5a602b070c3d 100644
--- a/libcxx/include/__thread/id.h
+++ b/libcxx/include/__thread/id.h
@@ -20,9 +20,10 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_HAS_THREADS
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_HAS_THREADS
 class __thread_id;
 
 namespace this_thread {
@@ -114,8 +115,8 @@ inline _LIBCPP_HIDE_FROM_ABI __thread_id get_id() _NOEXCEPT { return __libcpp_th
 
 } // namespace this_thread
 
-#endif // _LIBCPP_HAS_THREADS
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_HAS_THREADS
+
 #endif // _LIBCPP___THREAD_ID_H
diff --git a/libcxx/include/__tuple/sfinae_helpers.h b/libcxx/include/__tuple/sfinae_helpers.h
index f81048f4062b..78b00964a289 100644
--- a/libcxx/include/__tuple/sfinae_helpers.h
+++ b/libcxx/include/__tuple/sfinae_helpers.h
@@ -15,10 +15,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #ifndef _LIBCPP_CXX03_LANG
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 struct __check_tuple_constructor_fail {
   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit_default() { return false; }
   static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit_default() { return false; }
@@ -35,9 +35,8 @@ struct __check_tuple_constructor_fail {
     return false;
   }
 };
-#endif // !defined(_LIBCPP_CXX03_LANG)
 
-#if _LIBCPP_STD_VER >= 17
+#  if _LIBCPP_STD_VER >= 17
 
 template <bool _CanCopy, bool _CanMove>
 struct __sfinae_ctor_base {};
@@ -92,8 +91,10 @@ struct __sfinae_assign_base<false, true> {
   __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
   __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = default;
 };
-#endif // _LIBCPP_STD_VER >= 17
+#  endif // _LIBCPP_STD_VER >= 17
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // !defined(_LIBCPP_CXX03_LANG)
+
 #endif // _LIBCPP___TUPLE_SFINAE_HELPERS_H
diff --git a/libcxx/include/__tuple/tuple_like.h b/libcxx/include/__tuple/tuple_like.h
index c080a3dcf1e2..403f7d13eee5 100644
--- a/libcxx/include/__tuple/tuple_like.h
+++ b/libcxx/include/__tuple/tuple_like.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp>
 inline constexpr bool __is_ranges_subrange_v = false;
 
@@ -35,8 +35,8 @@ concept __tuple_like = __tuple_like_no_subrange<_Tp> || __is_ranges_subrange_v<r
 // As of writing this comment every use of `pair-like` in the standard excludes `ranges::subrange`, so
 // you most likely want to use `__pair_like_no_subrange` if you're looking for `pair-like`.
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___TUPLE_TUPLE_LIKE_H
diff --git a/libcxx/include/__tuple/tuple_like_no_subrange.h b/libcxx/include/__tuple/tuple_like_no_subrange.h
index 30018d6a05ae..8122b2e6b79f 100644
--- a/libcxx/include/__tuple/tuple_like_no_subrange.h
+++ b/libcxx/include/__tuple/tuple_like_no_subrange.h
@@ -22,10 +22,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp>
 inline constexpr bool __tuple_like_no_subrange_impl = false;
 
@@ -54,8 +54,8 @@ concept __tuple_like_no_subrange = __tuple_like_no_subrange_impl<remove_cvref_t<
 template <class _Tp>
 concept __pair_like_no_subrange = __tuple_like_no_subrange<_Tp> && tuple_size<remove_cvref_t<_Tp>>::value == 2;
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___TUPLE_TUPLE_LIKE_NO_SUBRANGE_H
diff --git a/libcxx/include/__type_traits/common_reference.h b/libcxx/include/__type_traits/common_reference.h
index 59badb64267d..793ba06ea4cb 100644
--- a/libcxx/include/__type_traits/common_reference.h
+++ b/libcxx/include/__type_traits/common_reference.h
@@ -24,10 +24,12 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER >= 20
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // common_reference
-#if _LIBCPP_STD_VER >= 20
+
 // Let COND_RES(X, Y) be:
 template <class _Xp, class _Yp>
 using __cond_res _LIBCPP_NODEBUG = decltype(false ? std::declval<_Xp (&)()>()() : std::declval<_Yp (&)()>()());
@@ -195,8 +197,8 @@ _LIBCPP_DIAGNOSTIC_POP
 template <class...>
 struct _LIBCPP_NO_SPECIALIZATIONS common_reference {};
 
-#endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 20
+
 #endif // _LIBCPP___TYPE_TRAITS_COMMON_REFERENCE_H
diff --git a/libcxx/include/__type_traits/has_unique_object_representation.h b/libcxx/include/__type_traits/has_unique_object_representation.h
index af9abfe81d41..9b0c3fd3cb73 100644
--- a/libcxx/include/__type_traits/has_unique_object_representation.h
+++ b/libcxx/include/__type_traits/has_unique_object_representation.h
@@ -16,10 +16,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp>
 struct _LIBCPP_NO_SPECIALIZATIONS has_unique_object_representations
     : integral_constant<bool, __has_unique_object_representations(_Tp)> {};
@@ -28,8 +28,8 @@ template <class _Tp>
 _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool has_unique_object_representations_v =
     __has_unique_object_representations(_Tp);
 
-#endif
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___TYPE_TRAITS_HAS_UNIQUE_OBJECT_REPRESENTATION_H
diff --git a/libcxx/include/__type_traits/is_implicit_lifetime.h b/libcxx/include/__type_traits/is_implicit_lifetime.h
index e5d1c05c437f..1222acba54e5 100644
--- a/libcxx/include/__type_traits/is_implicit_lifetime.h
+++ b/libcxx/include/__type_traits/is_implicit_lifetime.h
@@ -16,9 +16,10 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER >= 23
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 23
 #  if __has_builtin(__builtin_is_implicit_lifetime)
 
 template <class _Tp>
@@ -28,8 +29,9 @@ template <class _Tp>
 _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool is_implicit_lifetime_v = __builtin_is_implicit_lifetime(_Tp);
 
 #  endif
-#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___TYPE_TRAITS_IS_IMPLICIT_LIFETIME_H
diff --git a/libcxx/include/__type_traits/is_implicitly_default_constructible.h b/libcxx/include/__type_traits/is_implicitly_default_constructible.h
index d5dadd7b870d..80a3d86e1986 100644
--- a/libcxx/include/__type_traits/is_implicitly_default_constructible.h
+++ b/libcxx/include/__type_traits/is_implicitly_default_constructible.h
@@ -17,9 +17,10 @@
 #  pragma GCC system_header
 #endif
 
+#ifndef _LIBCPP_CXX03_LANG
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#ifndef _LIBCPP_CXX03_LANG
 // First of all, we can't implement this check in C++03 mode because the {}
 // default initialization syntax isn't valid.
 // Second, we implement the trait in a funny manner with two defaulted template
@@ -39,8 +40,9 @@ template <class _Tp>
 struct __is_implicitly_default_constructible<_Tp,
                                              decltype(std::__test_implicit_default_constructible<_Tp const&>({})),
                                              false_type> : false_type {};
-#endif // !C++03
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_CXX03_LANG
+
 #endif // _LIBCPP___TYPE_TRAITS_IS_IMPLICITLY_DEFAULT_CONSTRUCTIBLE_H
diff --git a/libcxx/include/__type_traits/is_literal_type.h b/libcxx/include/__type_traits/is_literal_type.h
index 2e0df3ad1be3..264d36f4fdd4 100644
--- a/libcxx/include/__type_traits/is_literal_type.h
+++ b/libcxx/include/__type_traits/is_literal_type.h
@@ -16,9 +16,10 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
 template <class _Tp>
 struct _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_NO_SPECIALIZATIONS is_literal_type
     : integral_constant<bool, __is_literal_type(_Tp)> {};
@@ -27,8 +28,9 @@ struct _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_NO_SPECIALIZATIONS is_literal_type
 template <class _Tp>
 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool is_literal_type_v = __is_literal_type(_Tp);
 #  endif // _LIBCPP_STD_VER >= 17
-#endif   // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
+
 #endif // _LIBCPP___TYPE_TRAITS_IS_LITERAL_TYPE
diff --git a/libcxx/include/__type_traits/reference_converts_from_temporary.h b/libcxx/include/__type_traits/reference_converts_from_temporary.h
index 9c51225e53b8..31479e43ee2c 100644
--- a/libcxx/include/__type_traits/reference_converts_from_temporary.h
+++ b/libcxx/include/__type_traits/reference_converts_from_temporary.h
@@ -16,10 +16,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp, class _Up>
 struct _LIBCPP_NO_SPECIALIZATIONS reference_converts_from_temporary
     : public bool_constant<__reference_converts_from_temporary(_Tp, _Up)> {};
@@ -28,8 +28,8 @@ template <class _Tp, class _Up>
 _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool reference_converts_from_temporary_v =
     __reference_converts_from_temporary(_Tp, _Up);
 
-#endif
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif //  _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___TYPE_TRAITS_REFERENCE_CONVERTS_FROM_TEMPORARY_H
diff --git a/libcxx/include/__type_traits/result_of.h b/libcxx/include/__type_traits/result_of.h
index 1714cf4dd96a..8073882f1358 100644
--- a/libcxx/include/__type_traits/result_of.h
+++ b/libcxx/include/__type_traits/result_of.h
@@ -16,18 +16,19 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // result_of
 
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
 template <class _Callable>
 struct _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_NO_SPECIALIZATIONS result_of;
 
 _LIBCPP_DIAGNOSTIC_PUSH
-#if __has_warning("-Winvalid-specialization")
+#  if __has_warning("-Winvalid-specialization")
 _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Winvalid-specialization")
-#endif
+#  endif
 template <class _Fp, class... _Args>
 struct result_of<_Fp(_Args...)> : __invoke_result<_Fp, _Args...> {};
 _LIBCPP_DIAGNOSTIC_POP
@@ -36,8 +37,9 @@ _LIBCPP_DIAGNOSTIC_POP
 template <class _Tp>
 using result_of_t _LIBCPP_DEPRECATED_IN_CXX17 = typename result_of<_Tp>::type;
 #  endif // _LIBCPP_STD_VER >= 14
-#endif   // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
+
 #endif // _LIBCPP___TYPE_TRAITS_RESULT_OF_H
diff --git a/libcxx/include/__utility/as_const.h b/libcxx/include/__utility/as_const.h
index 0f54b984725c..a9bc592e451f 100644
--- a/libcxx/include/__utility/as_const.h
+++ b/libcxx/include/__utility/as_const.h
@@ -15,9 +15,10 @@
 #  pragma GCC system_header
 #endif
 
+#if _LIBCPP_STD_VER >= 17
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 17
 template <class _Tp>
 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& as_const(_Tp& __t) noexcept {
   return __t;
@@ -25,8 +26,9 @@ template <class _Tp>
 
 template <class _Tp>
 void as_const(const _Tp&&) = delete;
-#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___UTILITY_AS_CONST_H
diff --git a/libcxx/include/__utility/forward_like.h b/libcxx/include/__utility/forward_like.h
index 409f716cfbce..42603f977363 100644
--- a/libcxx/include/__utility/forward_like.h
+++ b/libcxx/include/__utility/forward_like.h
@@ -21,10 +21,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Ap, class _Bp>
 using _CopyConst _LIBCPP_NODEBUG = _If<is_const_v<_Ap>, const _Bp, _Bp>;
 
@@ -56,8 +56,8 @@ __forward_as(_LIBCPP_LIFETIMEBOUND _Up&& __val) noexcept {
   return static_cast<_ForwardLike<_Tp, _As>>(__val);
 }
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___UTILITY_FORWARD_LIKE_H
diff --git a/libcxx/include/__utility/in_place.h b/libcxx/include/__utility/in_place.h
index c5bfa947058f..7c2ed0f9e2cd 100644
--- a/libcxx/include/__utility/in_place.h
+++ b/libcxx/include/__utility/in_place.h
@@ -18,10 +18,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 struct in_place_t {
   explicit in_place_t() = default;
 };
@@ -57,8 +57,8 @@ struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {};
 template <class _Tp>
 using __is_inplace_index _LIBCPP_NODEBUG = __is_inplace_index_imp<__remove_cvref_t<_Tp>>;
 
-#endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___UTILITY_IN_PLACE_H
diff --git a/libcxx/include/__variant/monostate.h b/libcxx/include/__variant/monostate.h
index 3939e42a9477..a11a51ecc087 100644
--- a/libcxx/include/__variant/monostate.h
+++ b/libcxx/include/__variant/monostate.h
@@ -19,10 +19,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 struct monostate {};
 
 _LIBCPP_HIDE_FROM_ABI inline constexpr bool operator==(monostate, monostate) noexcept { return true; }
@@ -59,8 +59,8 @@ struct hash<monostate> {
   }
 };
 
-#endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 17
+
 #endif // _LIBCPP___VARIANT_MONOSTATE_H
diff --git a/libcxx/include/__verbose_trap b/libcxx/include/__verbose_trap
index 6bda3e208ad4..d73a93871a39 100644
--- a/libcxx/include/__verbose_trap
+++ b/libcxx/include/__verbose_trap
@@ -16,14 +16,10 @@
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if __has_builtin(__builtin_verbose_trap)
 #  define _LIBCPP_VERBOSE_TRAP(message) __builtin_verbose_trap("libc++", message)
 #else
 #  define _LIBCPP_VERBOSE_TRAP(message) ((void)message, __builtin_trap())
 #endif
 
-_LIBCPP_END_NAMESPACE_STD
-
 #endif // _LIBCPP___VERBOSE_TRAP
diff --git a/libcxx/include/any b/libcxx/include/any
index 6157713a4069..670b7512e569 100644
--- a/libcxx/include/any
+++ b/libcxx/include/any
@@ -130,10 +130,10 @@ public:
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_UNVERSIONED_NAMESPACE_STD
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 [[noreturn]] inline _LIBCPP_HIDE_FROM_ABI void __throw_bad_any_cast() {
 #    if _LIBCPP_HAS_EXCEPTIONS
   throw bad_any_cast();
@@ -552,10 +552,10 @@ template <class _ValueType>
   return nullptr;
 }
 
-#  endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_STD_VER >= 17
+
 _LIBCPP_POP_MACROS
 
 #  if defined(_LIBCPP_KEEP_TRANSITIVE_INCLUDES_LLVM23) && _LIBCPP_STD_VER <= 17
diff --git a/libcxx/include/charconv b/libcxx/include/charconv
index 5d31957bf81f..b7d8cccd7ad7 100644
--- a/libcxx/include/charconv
+++ b/libcxx/include/charconv
@@ -100,10 +100,6 @@ namespace std {
 #    pragma GCC system_header
 #  endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-_LIBCPP_END_NAMESPACE_STD
-
 #  if defined(_LIBCPP_KEEP_TRANSITIVE_INCLUDES_LLVM23) && _LIBCPP_STD_VER <= 20
 #    include <cmath>
 #    include <concepts>
diff --git a/libcxx/include/cuchar b/libcxx/include/cuchar
index 38505eb336f8..591f332c70da 100644
--- a/libcxx/include/cuchar
+++ b/libcxx/include/cuchar
@@ -56,10 +56,10 @@ size_t c32rtomb(char* s, char32_t c32, mbstate_t* ps);
 #    pragma GCC system_header
 #  endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if !defined(_LIBCPP_CXX03_LANG)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 using ::mbstate_t _LIBCPP_USING_IF_EXISTS;
 
 #    if _LIBCPP_HAS_C8RTOMB_MBRTOC8
@@ -71,10 +71,10 @@ using ::c16rtomb _LIBCPP_USING_IF_EXISTS;
 using ::mbrtoc32 _LIBCPP_USING_IF_EXISTS;
 using ::c32rtomb _LIBCPP_USING_IF_EXISTS;
 
-#  endif // _LIBCPP_CXX03_LANG
-
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_CXX03_LANG
+
 #endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 
 #endif // _LIBCPP_CUCHAR
diff --git a/libcxx/include/experimental/memory b/libcxx/include/experimental/memory
index b6d7b16cb659..b7a499956170 100644
--- a/libcxx/include/experimental/memory
+++ b/libcxx/include/experimental/memory
@@ -70,10 +70,10 @@ public:
 
 #  ifdef _LIBCPP_ENABLE_EXPERIMENTAL
 
-_LIBCPP_BEGIN_NAMESPACE_LFTS_V2
-
 #    if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_LFTS_V2
+
 template <class _Wp>
 class observer_ptr {
 public:
@@ -175,25 +175,23 @@ _LIBCPP_HIDE_FROM_ABI bool operator>=(observer_ptr<_W1> __a, observer_ptr<_W2> _
   return !(__a < __b);
 }
 
-#    endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_LFTS_V2
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // hash
 
-#    if _LIBCPP_STD_VER >= 17
 template <class _Tp>
 struct hash<experimental::observer_ptr<_Tp>> {
   _LIBCPP_HIDE_FROM_ABI size_t operator()(const experimental::observer_ptr<_Tp>& __ptr) const noexcept {
     return hash<_Tp*>()(__ptr.get());
   }
 };
-#    endif // _LIBCPP_STD_VER >= 17
 
 _LIBCPP_END_NAMESPACE_STD
 
+#    endif // _LIBCPP_STD_VER >= 17
+
 #  endif // _LIBCPP_ENABLE_EXPERIMENTAL
 
 #  if defined(_LIBCPP_KEEP_TRANSITIVE_INCLUDES_LLVM23) && _LIBCPP_STD_VER <= 20
diff --git a/libcxx/include/initializer_list b/libcxx/include/initializer_list
index 36e45a6db258..a362a1020eb0 100644
--- a/libcxx/include/initializer_list
+++ b/libcxx/include/initializer_list
@@ -53,11 +53,11 @@ template<class E> const E* end(initializer_list<E> il) noexcept; // constexpr in
 #    pragma GCC system_header
 #  endif
 
+#  ifndef _LIBCPP_CXX03_LANG
+
 namespace std // purposefully not versioned
 {
 
-#  ifndef _LIBCPP_CXX03_LANG
-
 template <class _Ep>
 class _LIBCPP_NO_SPECIALIZATIONS initializer_list {
   const _Ep* __begin_;
@@ -101,10 +101,10 @@ inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Ep* end(initia
   return __il.end();
 }
 
-#  endif // !defined(_LIBCPP_CXX03_LANG)
-
 } // namespace std
 
+#  endif // _LIBCPP_CXX03_LANG
+
 #  if defined(_LIBCPP_KEEP_TRANSITIVE_INCLUDES_LLVM23) && _LIBCPP_STD_VER <= 20
 #    include <cstddef>
 #  endif
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
index ab505f945d63..75b080f8cd08 100644
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -214,11 +214,11 @@ template<class Callable, class ...Args>
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
+#  if _LIBCPP_HAS_THREADS
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
-#  if _LIBCPP_HAS_THREADS
-
 class _LIBCPP_EXPORTED_FROM_ABI recursive_mutex {
   __libcpp_recursive_mutex_t __m_;
 
@@ -496,11 +496,12 @@ private:
 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(scoped_lock);
 
 #    endif // _LIBCPP_STD_VER >= 17
-#  endif   // _LIBCPP_HAS_THREADS
 
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_HAS_THREADS
+
 _LIBCPP_POP_MACROS
 
 #  if defined(_LIBCPP_KEEP_TRANSITIVE_INCLUDES_LLVM23) && _LIBCPP_STD_VER <= 23
diff --git a/libcxx/include/print b/libcxx/include/print
index 4a3676f97b2d..cf62743846f4 100644
--- a/libcxx/include/print
+++ b/libcxx/include/print
@@ -52,13 +52,15 @@ namespace std {
 #    pragma GCC system_header
 #  endif
 
+#  if _LIBCPP_STD_VER >= 23
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#  ifdef _LIBCPP_WIN32API
+#    ifdef _LIBCPP_WIN32API
 _LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_EXPORTED_FROM_ABI bool __is_windows_terminal(FILE* __stream);
 
-#    if _LIBCPP_HAS_WIDE_CHARACTERS
+#      if _LIBCPP_HAS_WIDE_CHARACTERS
 // A wrapper for WriteConsoleW which is used to write to the Windows
 // console. This function is in the dylib to avoid pulling in windows.h
 // in the library headers. The function itself uses some private parts
@@ -69,11 +71,9 @@ _LIBCPP_EXPORTED_FROM_ABI bool __is_windows_terminal(FILE* __stream);
 //
 // Note the function is only implemented on the Windows platform.
 _LIBCPP_EXPORTED_FROM_ABI void __write_to_windows_console(FILE* __stream, wstring_view __view);
-#    endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#      endif // _LIBCPP_HAS_WIDE_CHARACTERS
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
-#  endif   // _LIBCPP_WIN32API
-
-#  if _LIBCPP_STD_VER >= 23
+#    endif   // _LIBCPP_WIN32API
 
 #    if _LIBCPP_HAS_UNICODE
 // This is the code to transcode UTF-8 to UTF-16. This is used on
@@ -378,10 +378,10 @@ _LIBCPP_HIDE_FROM_ABI inline void vprint_nonunicode(string_view __fmt, format_ar
   std::vprint_nonunicode(stdout, __fmt, __args);
 }
 
-#  endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_STD_VER >= 23
+
 #endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 
 #endif // _LIBCPP_PRINT
diff --git a/libcxx/include/scoped_allocator b/libcxx/include/scoped_allocator
index 13bdc496523b..edb3beae9749 100644
--- a/libcxx/include/scoped_allocator
+++ b/libcxx/include/scoped_allocator
@@ -135,10 +135,10 @@ template <class OuterA1, class OuterA2, class... InnerAllocs>
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if !defined(_LIBCPP_CXX03_LANG)
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // scoped_allocator_adaptor
 
 template <class... _Allocs>
@@ -558,10 +558,10 @@ inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const scoped_allocator_adaptor<_Out
 
 #    endif // _LIBCPP_STD_VER <= 17
 
-#  endif // !defined(_LIBCPP_CXX03_LANG)
-
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // !defined(_LIBCPP_CXX03_LANG)
+
 _LIBCPP_POP_MACROS
 
 #  if defined(_LIBCPP_KEEP_TRANSITIVE_INCLUDES_LLVM23) && _LIBCPP_STD_VER <= 20
diff --git a/libcxx/include/source_location b/libcxx/include/source_location
index 41b23f70c662..6913b049946a 100644
--- a/libcxx/include/source_location
+++ b/libcxx/include/source_location
@@ -36,10 +36,10 @@ namespace std {
 #    pragma GCC system_header
 #  endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 class source_location {
   // The names source_location::__impl, _M_file_name, _M_function_name, _M_line, and _M_column
   // are hard-coded in the compiler and must not be changed here.
@@ -81,10 +81,10 @@ public:
   }
 };
 
-#  endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_STD_VER >= 20
+
 #endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 
 #endif // _LIBCPP_SOURCE_LOCATION
diff --git a/libcxx/include/span b/libcxx/include/span
index 49954df9515d..e39b811f9b1e 100644
--- a/libcxx/include/span
+++ b/libcxx/include/span
@@ -198,10 +198,10 @@ template<class R>
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 20
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <class _Tp>
 struct __is_std_span : false_type {};
 
@@ -630,10 +630,10 @@ span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>;
 template <ranges::contiguous_range _Range>
 span(_Range&&) -> span<remove_reference_t<ranges::range_reference_t<_Range>>>;
 
-#  endif // _LIBCPP_STD_VER >= 20
-
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_STD_VER >= 20
+
 _LIBCPP_POP_MACROS
 
 #  if defined(_LIBCPP_KEEP_TRANSITIVE_INCLUDES_LLVM23) && _LIBCPP_STD_VER <= 20
diff --git a/libcxx/include/syncstream b/libcxx/include/syncstream
index bd64453683c7..03e18ddbdfd2 100644
--- a/libcxx/include/syncstream
+++ b/libcxx/include/syncstream
@@ -147,10 +147,10 @@ namespace std {
 _LIBCPP_PUSH_MACROS
 #    include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #    if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // [syncstream.syncbuf.overview]/1
 //   Class template basic_syncbuf stores character data written to it,
 //   known as the associated output, into internal buffers allocated
@@ -511,10 +511,10 @@ using std::osyncstream;
 using std::wosyncstream;
 #      endif
 
-#    endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM
-
 _LIBCPP_END_NAMESPACE_STD
 
+#    endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM
+
 _LIBCPP_POP_MACROS
 
 #  endif // _LIBCPP_HAS_LOCALIZATION
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
index 3785bb9961f3..8f43006521dd 100644
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -283,10 +283,10 @@ template <class... Types>
 _LIBCPP_PUSH_MACROS
 #  include <__undef_macros>
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  ifndef _LIBCPP_CXX03_LANG
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 template <size_t _Ip, class _Tp, class _Up>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool __tuple_compare_equal(const _Tp& __x, const _Up& __y) {
   if constexpr (_Ip == 0)
@@ -1443,10 +1443,10 @@ template <class _Tp, class _Tuple, class = enable_if_t<__can_make_from_tuple<_Tp
 
 #  endif // _LIBCPP_STD_VER >= 17
 
-#endif // !defined(_LIBCPP_CXX03_LANG)
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // !defined(_LIBCPP_CXX03_LANG)
+
 _LIBCPP_POP_MACROS
 
 // clang-format on
diff --git a/libcxx/include/variant b/libcxx/include/variant
index 8d76931e65de..cf3bd82ee7c1 100644
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -307,10 +307,10 @@ private:
 _LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_UNVERSIONED_NAMESPACE_STD
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #  if _LIBCPP_STD_VER >= 17
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 // Light N-dimensional array of function pointers. Used in place of std::array to avoid
 // adding a dependency.
 template <class _Tp, size_t _Size>
@@ -1655,10 +1655,10 @@ _LIBCPP_HIDE_FROM_ABI constexpr auto&& __unchecked_get(variant<_Types...>& __v)
   return std::__unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
 }
 
-#  endif // _LIBCPP_STD_VER >= 17
-
 _LIBCPP_END_NAMESPACE_STD
 
+#  endif // _LIBCPP_STD_VER >= 17
+
 _LIBCPP_POP_MACROS
 
 #  if defined(_LIBCPP_KEEP_TRANSITIVE_INCLUDES_LLVM23) && _LIBCPP_STD_VER <= 20
diff --git a/libcxx/test/tools/clang_tidy_checks/CMakeLists.txt b/libcxx/test/tools/clang_tidy_checks/CMakeLists.txt
index 3663575e33e5..8e125e51344f 100644
--- a/libcxx/test/tools/clang_tidy_checks/CMakeLists.txt
+++ b/libcxx/test/tools/clang_tidy_checks/CMakeLists.txt
@@ -88,6 +88,7 @@ message(STATUS "Clang-tidy tests are enabled.")
 
 set(SOURCES
     abi_tag_on_virtual.cpp
+    empty_namespaces.cpp
     header_exportable_declarations.cpp
     hide_from_abi.cpp
     internal_ftm_use.cpp
diff --git a/libcxx/test/tools/clang_tidy_checks/empty_namespaces.cpp b/libcxx/test/tools/clang_tidy_checks/empty_namespaces.cpp
new file mode 100644
index 000000000000..e176b29670ce
--- /dev/null
+++ b/libcxx/test/tools/clang_tidy_checks/empty_namespaces.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang-tidy/ClangTidyCheck.h"
+#include "clang-tidy/ClangTidyModuleRegistry.h"
+
+#include "empty_namespaces.hpp"
+
+namespace libcpp {
+empty_namespaces::empty_namespaces(llvm::StringRef name, clang::tidy::ClangTidyContext* context)
+    : clang::tidy::ClangTidyCheck(name, context) {}
+
+void empty_namespaces::registerMatchers(clang::ast_matchers::MatchFinder* finder) {
+  using namespace clang::ast_matchers;
+  finder->addMatcher(namespaceDecl(unless(hasDescendant(decl()))).bind("empty_namespace"), this);
+}
+
+void empty_namespaces::check(const clang::ast_matchers::MatchFinder::MatchResult& result) {
+  if (const auto* ns = result.Nodes.getNodeAs<clang::NamespaceDecl>("empty_namespace")) {
+    diag(ns->getBeginLoc(), "Empty namespaces should be avoided. Move any checks around the namespace instead.");
+  }
+}
+} // namespace libcpp
diff --git a/libcxx/test/tools/clang_tidy_checks/empty_namespaces.hpp b/libcxx/test/tools/clang_tidy_checks/empty_namespaces.hpp
new file mode 100644
index 000000000000..2b69eadf25fe
--- /dev/null
+++ b/libcxx/test/tools/clang_tidy_checks/empty_namespaces.hpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang-tidy/ClangTidyCheck.h"
+
+namespace libcpp {
+class empty_namespaces : public clang::tidy::ClangTidyCheck {
+public:
+  empty_namespaces(llvm::StringRef, clang::tidy::ClangTidyContext*);
+  void registerMatchers(clang::ast_matchers::MatchFinder*) override;
+  void check(const clang::ast_matchers::MatchFinder::MatchResult&) override;
+};
+} // namespace libcpp
diff --git a/libcxx/test/tools/clang_tidy_checks/libcpp_module.cpp b/libcxx/test/tools/clang_tidy_checks/libcpp_module.cpp
index 2cf39e2b626f..b6298eefdeb4 100644
--- a/libcxx/test/tools/clang_tidy_checks/libcpp_module.cpp
+++ b/libcxx/test/tools/clang_tidy_checks/libcpp_module.cpp
@@ -10,6 +10,7 @@
 #include "clang-tidy/ClangTidyModuleRegistry.h"
 
 #include "abi_tag_on_virtual.hpp"
+#include "empty_namespaces.hpp"
 #include "header_exportable_declarations.hpp"
 #include "hide_from_abi.hpp"
 #include "internal_ftm_use.hpp"
@@ -24,6 +25,7 @@ class LibcxxTestModule : public clang::tidy::ClangTidyModule {
 public:
   void addCheckFactories(clang::tidy::ClangTidyCheckFactories& check_factories) override {
     check_factories.registerCheck<libcpp::abi_tag_on_virtual>("libcpp-avoid-abi-tag-on-virtual");
+    check_factories.registerCheck<libcpp::empty_namespaces>("libcpp-avoid-empty-namespaces");
     check_factories.registerCheck<libcpp::header_exportable_declarations>("libcpp-header-exportable-declarations");
     check_factories.registerCheck<libcpp::hide_from_abi>("libcpp-hide-from-abi");
     check_factories.registerCheck<libcpp::internal_ftm_use>("libcpp-internal-ftms");
diff --git a/libcxx/utils/generate_escaped_output_table.py b/libcxx/utils/generate_escaped_output_table.py
index 30583dd8cdc8..ce9ac93e0bcb 100755
--- a/libcxx/utils/generate_escaped_output_table.py
+++ b/libcxx/utils/generate_escaped_output_table.py
@@ -226,20 +226,20 @@ TABLES_HPP_TEMPLATE = """
 #  pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
 #if _LIBCPP_STD_VER >= 23
 
+_LIBCPP_BEGIN_NAMESPACE_STD
+
 namespace __escaped_output_table {{
 // clang-format off
 {content}
 // clang-format on
 }} // namespace __escaped_output_table
 
-#endif // _LIBCPP_STD_VER >= 23
-
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP___FORMAT_ESCAPED_OUTPUT_TABLE_H"""