https://gcc.gnu.org/g:58564c85c5dd221b26c65a26b4bd0a6ccb6e3178

commit r16-8523-g58564c85c5dd221b26c65a26b4bd0a6ccb6e3178
Author: Tomasz Kamiński <[email protected]>
Date:   Tue Apr 7 13:19:20 2026 +0200

    libstdc++: Move constant_wrapper from <type_traits> to <utility>
    
    Change placement of constant_wrapper and related classes per
    P3978R3: constant_wrapper should unwrap on call and subscript.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/utility.h (std::_CwFixedValue, std::_ConstExprParam)
            (std::_CwOperators, std::constant_wrapper): Moved from...
            * include/std/type_traits (std::_CwFixedValue, std::_ConstExprParam)
            (std::_CwOperators, std::constant_wrapper): Moved to bits/utility.h.
            Disable __cpp_lib_constant_wrapper defintion.
            * include/std/utility: Define __cpp_lib_constant_wrapper.
            * testsuite/20_util/constant_wrapper/adl.cc: Updated header 
includes.
            * testsuite/20_util/constant_wrapper/ex.cc: Likewise.
            * testsuite/20_util/constant_wrapper/generic.cc: Likewise.
            * testsuite/20_util/constant_wrapper/instantiate.cc: Likewise.
            * testsuite/20_util/constant_wrapper/op_comma_neg.cc: Likewise.
            * testsuite/20_util/constant_wrapper/other_wrappers.cc: Likewise.
            * testsuite/20_util/constant_wrapper/version.cc: Likewise.
    
    Reviewed-by: Jonathan Wakely <[email protected]>
    Signed-off-by: Tomasz Kamiński <[email protected]>

Diff:
---
 libstdc++-v3/include/bits/utility.h                | 325 ++++++++++++++++++++
 libstdc++-v3/include/std/type_traits               | 326 ---------------------
 libstdc++-v3/include/std/utility                   |   1 +
 .../testsuite/20_util/constant_wrapper/adl.cc      |   2 +-
 .../testsuite/20_util/constant_wrapper/ex.cc       |   2 +-
 .../testsuite/20_util/constant_wrapper/generic.cc  |   1 -
 .../20_util/constant_wrapper/instantiate.cc        |   1 -
 .../20_util/constant_wrapper/op_comma_neg.cc       |   2 +-
 .../20_util/constant_wrapper/other_wrappers.cc     |   2 +-
 .../testsuite/20_util/constant_wrapper/version.cc  |   4 +-
 10 files changed, 332 insertions(+), 334 deletions(-)

diff --git a/libstdc++-v3/include/bits/utility.h 
b/libstdc++-v3/include/bits/utility.h
index bd6b18d54dd3..970e63e81706 100644
--- a/libstdc++-v3/include/bits/utility.h
+++ b/libstdc++-v3/include/bits/utility.h
@@ -137,6 +137,331 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     using tuple_element_t = typename tuple_element<__i, _Tp>::type;
 #endif
 
+#ifdef __glibcxx_constant_wrapper // C++ >= 26
+  template<typename _Tp>
+    struct _CwFixedValue
+    {
+      using __type = _Tp;
+
+      constexpr
+      _CwFixedValue(__type __v) noexcept
+      : _M_data(__v) { }
+
+      __type _M_data;
+    };
+
+  template<typename _Tp, size_t _Extent>
+    struct _CwFixedValue<_Tp[_Extent]>
+    {
+      using __type = _Tp[_Extent];
+
+      constexpr
+      _CwFixedValue(_Tp (&__arr)[_Extent]) noexcept
+        : _CwFixedValue(__arr, typename _Build_index_tuple<_Extent>::__type())
+      { }
+
+      template<size_t... _Indices>
+       constexpr
+       _CwFixedValue(_Tp (&__arr)[_Extent], _Index_tuple<_Indices...>) noexcept
+         : _M_data{__arr[_Indices]...}
+       { }
+
+      _Tp _M_data[_Extent];
+    };
+
+  template<typename _Tp, size_t _Extent>
+    _CwFixedValue(_Tp (&)[_Extent]) -> _CwFixedValue<_Tp[_Extent]>;
+
+  template<_CwFixedValue _Xv,
+          typename = typename decltype(_CwFixedValue(_Xv))::__type>
+    struct constant_wrapper;
+
+  template<typename _Tp>
+    concept _ConstExprParam = requires
+    {
+      typename constant_wrapper<_Tp::value>;
+    };
+
+  struct _CwOperators
+  {
+    template<_ConstExprParam _Tp>
+      friend constexpr auto
+      operator+(_Tp) noexcept -> constant_wrapper<(+_Tp::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      friend constexpr auto
+      operator-(_Tp) noexcept -> constant_wrapper<(-_Tp::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      friend constexpr auto
+      operator~(_Tp) noexcept -> constant_wrapper<(~_Tp::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      friend constexpr auto
+      operator!(_Tp) noexcept -> constant_wrapper<(!_Tp::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      friend constexpr auto
+      operator&(_Tp) noexcept -> constant_wrapper<(&_Tp::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      friend constexpr auto
+      operator*(_Tp) noexcept -> constant_wrapper<(*_Tp::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator+(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value + _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator-(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value - _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator*(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value * _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator/(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value / _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator%(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value % _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator<<(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value << _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator>>(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value >> _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator&(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value & _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator|(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value | _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator^(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value ^ _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      requires (!is_constructible_v<bool, decltype(_Left::value)>
+               || !is_constructible_v<bool, decltype(_Right::value)>)
+      friend constexpr auto
+      operator&&(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value && _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      requires (!is_constructible_v<bool, decltype(_Left::value)>
+               || !is_constructible_v<bool, decltype(_Right::value)>)
+      friend constexpr auto
+      operator||(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value || _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator<=>(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value <=> _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator<(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value < _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator<=(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value <= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator==(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value == _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator!=(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value != _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator>(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value > _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator>=(_Left, _Right) noexcept
+       -> constant_wrapper<(_Left::value >= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator,(_Left, _Right) noexcept = delete;
+
+    template<_ConstExprParam _Left, _ConstExprParam _Right>
+      friend constexpr auto
+      operator->*(_Left, _Right) noexcept
+       -> constant_wrapper<_Left::value->*(_Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam... _Args>
+      constexpr auto
+      operator()(this _Tp, _Args...) noexcept
+      requires
+       requires(_Args...) { constant_wrapper<_Tp::value(_Args::value...)>(); }
+      { return constant_wrapper<_Tp::value(_Args::value...)>{}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam... _Args>
+      constexpr auto
+      operator[](this _Tp, _Args...) noexcept
+       -> constant_wrapper<(_Tp::value[_Args::value...])>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      constexpr auto
+      operator++(this _Tp) noexcept
+       -> constant_wrapper<(++_Tp::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      constexpr auto
+      operator++(this _Tp, int) noexcept
+       -> constant_wrapper<(_Tp::value++)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      constexpr auto
+      operator--(this _Tp) noexcept
+       -> constant_wrapper<(--_Tp::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp>
+      constexpr auto
+      operator--(this _Tp, int) noexcept
+       -> constant_wrapper<(_Tp::value--)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator+=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value += _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator-=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value -= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator*=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value *= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator/=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value /= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator%=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value %= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator&=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value &= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator|=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value |= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator^=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value ^= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator<<=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value <<= _Right::value)>
+      { return {}; }
+
+    template<_ConstExprParam _Tp, _ConstExprParam _Right>
+      constexpr auto
+      operator>>=(this _Tp, _Right) noexcept
+       -> constant_wrapper<(_Tp::value >>= _Right::value)>
+      { return {}; }
+  };
+
+  template<_CwFixedValue _Xv, typename>
+  struct constant_wrapper : _CwOperators
+  {
+    static constexpr const auto& value = _Xv._M_data;
+    using type = constant_wrapper;
+    using value_type = typename decltype(_Xv)::__type;
+
+    template<_ConstExprParam _Right>
+      constexpr auto
+      operator=(_Right) const noexcept
+       -> constant_wrapper<(value = _Right::value)>
+      { return {}; }
+
+    constexpr
+    operator decltype(value)() const noexcept
+    { return value; }
+  };
+
+  template<_CwFixedValue _Tp>
+    constexpr auto cw = constant_wrapper<_Tp>{};
+#endif
+
 #ifdef __glibcxx_integer_sequence // C++ >= 14
 
   /// Class template integer_sequence
diff --git a/libstdc++-v3/include/std/type_traits 
b/libstdc++-v3/include/std/type_traits
index 30214194da03..59be925e10a6 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -42,7 +42,6 @@
 #define __glibcxx_want_bool_constant
 #define __glibcxx_want_bounded_array_traits
 #define __glibcxx_want_common_reference
-#define __glibcxx_want_constant_wrapper
 #define __glibcxx_want_has_unique_object_representations
 #define __glibcxx_want_integral_constant_callable
 #define __glibcxx_want_is_aggregate
@@ -4385,331 +4384,6 @@ template<typename _Ret, typename _Fn, typename... _Args>
     };
 #endif // C++11
 
-#ifdef __cpp_lib_constant_wrapper // C++ >= 26
-  template<typename _Tp>
-    struct _CwFixedValue
-    {
-      using __type = _Tp;
-
-      constexpr
-      _CwFixedValue(__type __v) noexcept
-      : _M_data(__v) { }
-
-      __type _M_data;
-    };
-
-  template<typename _Tp, size_t _Extent>
-    struct _CwFixedValue<_Tp[_Extent]>
-    {
-      using __type = _Tp[_Extent];
-
-      constexpr
-      _CwFixedValue(_Tp (&__arr)[_Extent]) noexcept
-        : _CwFixedValue(__arr, typename _Build_index_tuple<_Extent>::__type())
-      { }
-
-      template<size_t... _Indices>
-       constexpr
-       _CwFixedValue(_Tp (&__arr)[_Extent], _Index_tuple<_Indices...>) noexcept
-         : _M_data{__arr[_Indices]...}
-       { }
-
-      _Tp _M_data[_Extent];
-    };
-
-  template<typename _Tp, size_t _Extent>
-    _CwFixedValue(_Tp (&)[_Extent]) -> _CwFixedValue<_Tp[_Extent]>;
-
-  template<_CwFixedValue _Xv,
-          typename = typename decltype(_CwFixedValue(_Xv))::__type>
-    struct constant_wrapper;
-
-  template<typename _Tp>
-    concept _ConstExprParam = requires
-    {
-      typename constant_wrapper<_Tp::value>;
-    };
-
-  struct _CwOperators
-  {
-    template<_ConstExprParam _Tp>
-      friend constexpr auto
-      operator+(_Tp) noexcept -> constant_wrapper<(+_Tp::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      friend constexpr auto
-      operator-(_Tp) noexcept -> constant_wrapper<(-_Tp::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      friend constexpr auto
-      operator~(_Tp) noexcept -> constant_wrapper<(~_Tp::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      friend constexpr auto
-      operator!(_Tp) noexcept -> constant_wrapper<(!_Tp::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      friend constexpr auto
-      operator&(_Tp) noexcept -> constant_wrapper<(&_Tp::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      friend constexpr auto
-      operator*(_Tp) noexcept -> constant_wrapper<(*_Tp::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator+(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value + _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator-(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value - _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator*(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value * _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator/(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value / _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator%(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value % _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator<<(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value << _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator>>(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value >> _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator&(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value & _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator|(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value | _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator^(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value ^ _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      requires (!is_constructible_v<bool, decltype(_Left::value)>
-               || !is_constructible_v<bool, decltype(_Right::value)>)
-      friend constexpr auto
-      operator&&(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value && _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      requires (!is_constructible_v<bool, decltype(_Left::value)>
-               || !is_constructible_v<bool, decltype(_Right::value)>)
-      friend constexpr auto
-      operator||(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value || _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator<=>(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value <=> _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator<(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value < _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator<=(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value <= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator==(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value == _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator!=(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value != _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator>(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value > _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator>=(_Left, _Right) noexcept
-       -> constant_wrapper<(_Left::value >= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator,(_Left, _Right) noexcept = delete;
-
-    template<_ConstExprParam _Left, _ConstExprParam _Right>
-      friend constexpr auto
-      operator->*(_Left, _Right) noexcept
-       -> constant_wrapper<_Left::value->*(_Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam... _Args>
-      constexpr auto
-      operator()(this _Tp, _Args...) noexcept
-      requires
-       requires(_Args...) { constant_wrapper<_Tp::value(_Args::value...)>(); }
-      { return constant_wrapper<_Tp::value(_Args::value...)>{}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam... _Args>
-      constexpr auto
-      operator[](this _Tp, _Args...) noexcept
-       -> constant_wrapper<(_Tp::value[_Args::value...])>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      constexpr auto
-      operator++(this _Tp) noexcept
-       -> constant_wrapper<(++_Tp::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      constexpr auto
-      operator++(this _Tp, int) noexcept
-       -> constant_wrapper<(_Tp::value++)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      constexpr auto
-      operator--(this _Tp) noexcept
-       -> constant_wrapper<(--_Tp::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp>
-      constexpr auto
-      operator--(this _Tp, int) noexcept
-       -> constant_wrapper<(_Tp::value--)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator+=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value += _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator-=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value -= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator*=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value *= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator/=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value /= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator%=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value %= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator&=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value &= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator|=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value |= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator^=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value ^= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator<<=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value <<= _Right::value)>
-      { return {}; }
-
-    template<_ConstExprParam _Tp, _ConstExprParam _Right>
-      constexpr auto
-      operator>>=(this _Tp, _Right) noexcept
-       -> constant_wrapper<(_Tp::value >>= _Right::value)>
-      { return {}; }
-  };
-
-  template<_CwFixedValue _Xv, typename>
-  struct constant_wrapper : _CwOperators
-  {
-    static constexpr const auto& value = _Xv._M_data;
-    using type = constant_wrapper;
-    using value_type = typename decltype(_Xv)::__type;
-
-    template<_ConstExprParam _Right>
-      constexpr auto
-      operator=(_Right) const noexcept
-       -> constant_wrapper<(value = _Right::value)>
-      { return {}; }
-
-    constexpr
-    operator decltype(value)() const noexcept
-    { return value; }
-  };
-
-  template<_CwFixedValue _Tp>
-    constexpr auto cw = constant_wrapper<_Tp>{};
-#endif
-
   /// @} group metaprogramming
 
 _GLIBCXX_END_NAMESPACE_VERSION
diff --git a/libstdc++-v3/include/std/utility b/libstdc++-v3/include/std/utility
index 7d9d3653cd00..2e1775bf6b3d 100644
--- a/libstdc++-v3/include/std/utility
+++ b/libstdc++-v3/include/std/utility
@@ -87,6 +87,7 @@
 
 #define __glibcxx_want_addressof_constexpr
 #define __glibcxx_want_as_const
+#define __glibcxx_want_constant_wrapper
 #define __glibcxx_want_constexpr_algorithms
 #define __glibcxx_want_constexpr_utility
 #define __glibcxx_want_exchange_function
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/adl.cc 
b/libstdc++-v3/testsuite/20_util/constant_wrapper/adl.cc
index 3cdc09c1eb74..3629e4fc5597 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/adl.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/adl.cc
@@ -1,5 +1,5 @@
 // { dg-do compile { target c++26 } }
-#include <type_traits>
+#include <utility>
 #include <concepts>
 
 #include <testsuite_hooks.h>
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/ex.cc 
b/libstdc++-v3/testsuite/20_util/constant_wrapper/ex.cc
index a4d967b96340..a5d19fd81324 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/ex.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/ex.cc
@@ -1,5 +1,5 @@
 // { dg-do compile { target c++26 } }
-#include <type_traits>
+#include <utility>
 #include <iostream>
 
 #include <testsuite_hooks.h>
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/generic.cc 
b/libstdc++-v3/testsuite/20_util/constant_wrapper/generic.cc
index de4334b64f5b..1c7770d7a899 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/generic.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/generic.cc
@@ -1,5 +1,4 @@
 // { dg-do run { target c++26 } }
-#include <type_traits>
 #include <utility>
 #include <string_view>
 
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/instantiate.cc 
b/libstdc++-v3/testsuite/20_util/constant_wrapper/instantiate.cc
index 5adf6fda5a38..452f01fadcdc 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/instantiate.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/instantiate.cc
@@ -1,5 +1,4 @@
 // { dg-do run { target c++26 } }
-#include <type_traits>
 #include <utility>
 
 #include <testsuite_hooks.h>
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/op_comma_neg.cc 
b/libstdc++-v3/testsuite/20_util/constant_wrapper/op_comma_neg.cc
index 4384e920ea58..2fc8c78c2da0 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/op_comma_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/op_comma_neg.cc
@@ -1,5 +1,5 @@
 // { dg-do compile { target c++26 } }
-#include <type_traits>
+#include <utility>
 
 constexpr void
 test_comma_same_types()
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/other_wrappers.cc 
b/libstdc++-v3/testsuite/20_util/constant_wrapper/other_wrappers.cc
index 3c3cfafd6ed3..fe45c5a85162 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/other_wrappers.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/other_wrappers.cc
@@ -1,5 +1,5 @@
 // { dg-do run { target c++26 } }
-#include <type_traits>
+#include <utility>
 #include <concepts>
 
 #include <testsuite_hooks.h>
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/version.cc 
b/libstdc++-v3/testsuite/20_util/constant_wrapper/version.cc
index 4fee6159141d..776d80c576a3 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/version.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/version.cc
@@ -1,10 +1,10 @@
 // { dg-do preprocess { target c++26 } }
 // { dg-add-options no_pch }
 
-#include <type_traits>
+#include <utility>
 
 #ifndef __cpp_lib_constant_wrapper
-#error "Feature test macro __cpp_lib_constant_wrapper is missing for 
<type_traits>"
+#error "Feature test macro __cpp_lib_constant_wrapper is missing for <utility>"
 #if __cpp_lib_constant_wrapper < 202506L
 #error "Feature test macro __cpp_lib_constant_wrapper has the wrong value"
 #endif

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