[gcc r14-8254] libstdc++/pair: Guard P2321R2 changes with __glibcxx_ranges_zip

[Patrick Palka <ppalka@gcc.gnu.org>]

https://gcc.gnu.org/g:8cddf6f833e1c7a132fff9fa407cedf9fdf38bd9

commit r14-8254-g8cddf6f833e1c7a132fff9fa407cedf9fdf38bd9
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Jan 18 11:21:34 2024 -0500

    libstdc++/pair: Guard P2321R2 changes with __glibcxx_ranges_zip
    
    Similar to the previous change for <tuple>, but since stl_pair.h is an
    internal header we need to use the corresponding internal macro instead.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/stl_pair.h [__cplusplus > 202002L]:
            Guard P2321R2 changes with __glibcxx_ranges_zip instead.
    
    Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

Diff:
---
 libstdc++-v3/include/bits/stl_pair.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/libstdc++-v3/include/bits/stl_pair.h b/libstdc++-v3/include/bits/stl_pair.h
index 52f532f3c39..acd0c7b58f9 100644
--- a/libstdc++-v3/include/bits/stl_pair.h
+++ b/libstdc++-v3/include/bits/stl_pair.h
@@ -211,7 +211,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	swap(second, __p.second);
       }
 
-#if __cplusplus > 202002L
+#if __glibcxx_ranges_zip // >= C++23
       // As an extension, we constrain the const swap member function in order
       // to continue accepting explicit instantiation of pairs whose elements
       // are not all const swappable.  Without this constraint, such an
@@ -360,7 +360,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	constexpr explicit(!_S_convertible<_U1, _U2>())
 	pair(pair<_U1, _U2>&&) = delete;
 
-#if __cplusplus > 202002L
+#if __glibcxx_ranges_zip // >= C++23
       /// Converting constructor from a non-const `pair<U1, U2>` lvalue
       template<typename _U1, typename _U2>
 	requires (_S_constructible<_U1&, _U2&>()) && (!_S_dangles<_U1&, _U2&>())
@@ -464,7 +464,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  return *this;
 	}
 
-#if __cplusplus > 202002L
+#if __glibcxx_ranges_zip // >= C++23
       /// Copy assignment operator (const)
       constexpr const pair&
       operator=(const pair& __p) const
@@ -887,7 +887,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     noexcept(noexcept(__x.swap(__y)))
     { __x.swap(__y); }
 
-#if __cplusplus > 202002L
+#if __glibcxx_ranges_zip // >= C++23
   template<typename _T1, typename _T2>
     requires is_swappable_v<const _T1> && is_swappable_v<const _T2>
     constexpr void
@@ -1101,7 +1101,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #endif // __glibcxx_tuples_by_type
 
 
-#if __cplusplus > 202002L
+#if __glibcxx_ranges_zip // >= C++23
   template<typename _T1, typename _T2, typename _U1, typename _U2,
 	   template<typename> class _TQual, template<typename> class _UQual>
     requires requires { typename pair<common_reference_t<_TQual<_T1>, _UQual<_U1>>,