LWG 3860 added this alias template. Both libc++ and MSVC treat this as a
DR for C++20, so this change does so too.
libstdc++-v3/ChangeLog:
* include/bits/ranges_base.h (range_common_reference_t): New
alias template, as per LWG 3860.
* testsuite/std/ranges/range.cc: Check it.
using range_rvalue_reference_t
= iter_rvalue_reference_t<iterator_t<_Range>>;
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 3860. range_common_reference_t is missing
+ template<range _Range>
+ using range_common_reference_t
+ = iter_common_reference_t<iterator_t<_Range>>;
+
/// [range.sized] The sized_range concept.
template<typename _Tp>
concept sized_range = range<_Tp>
char&&> );
static_assert( same_as<std::ranges::range_rvalue_reference_t<O>,
WritableObject<char>> );
+
+// LWG 3860. range_common_reference_t is missing
+static_assert( same_as<std::ranges::range_common_reference_t<C>,
+ char&> );
+static_assert( same_as<std::ranges::range_common_reference_t<I>,
+ char&> );