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 --git a/libstdc++-v3/include/bits/stl_pair.h b/libstdc++-v3/include/bits/stl_pair.h
index 52f532f3c39a3201de30dd14226f907e76a5a83a..acd0c7b58f91d40974ecfe6997d7c9e76ed1f781 100644 (file)
--- 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>>,