diff options
Diffstat (limited to 'libstdc++-v3/include/bits/refwrap.h')
| -rw-r--r-- | libstdc++-v3/include/bits/refwrap.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/libstdc++-v3/include/bits/refwrap.h b/libstdc++-v3/include/bits/refwrap.h index 612715e..5d9f8c8 100644 --- a/libstdc++-v3/include/bits/refwrap.h +++ b/libstdc++-v3/include/bits/refwrap.h @@ -457,6 +457,40 @@ _GLIBCXX_MEM_FN_TRAITS(&& noexcept, false_type, true_type) /// @} +#if __glibcxx_common_reference_wrapper // C++ >= 20 + namespace __detail + { + template<typename _Tp> + constexpr bool __is_ref_wrapper = false; + + template<typename _Tp> + constexpr bool __is_ref_wrapper<reference_wrapper<_Tp>> = true; + + template<typename _Rp, typename _Tp, typename _RQual, typename _TQual> + concept __ref_wrap_common_reference_exists_with = __is_ref_wrapper<_Rp> + && requires { typename common_reference_t<typename _Rp::type&, _TQual>; } + && convertible_to<_RQual, common_reference_t<typename _Rp::type&, _TQual>>; + } // namespace __detail + + template<typename _Rp, typename _Tp, + template<typename> class _RQual, template<typename> class _TQual> + requires __detail::__ref_wrap_common_reference_exists_with<_Rp, _Tp, + _RQual<_Rp>, _TQual<_Tp>> + && (!__detail::__ref_wrap_common_reference_exists_with<_Tp, _Rp, + _TQual<_Tp>, _RQual<_Rp>>) + struct basic_common_reference<_Rp, _Tp, _RQual, _TQual> + { using type = common_reference_t<typename _Rp::type&, _TQual<_Tp>>; }; + + template<typename _Tp, typename _Rp, + template<typename> class _TQual, template<typename> class _RQual> + requires __detail::__ref_wrap_common_reference_exists_with<_Rp, _Tp, + _RQual<_Rp>, _TQual<_Tp>> + && (!__detail::__ref_wrap_common_reference_exists_with<_Tp, _Rp, + _TQual<_Tp>, _RQual<_Rp>>) + struct basic_common_reference<_Tp, _Rp, _TQual, _RQual> + { using type = common_reference_t<typename _Rp::type&, _TQual<_Tp>>; }; +#endif + _GLIBCXX_END_NAMESPACE_VERSION } // namespace std |