libstdc++: Add code comment documenting LWG 4027 change [PR118083]

	PR libstdc++/118083

libstdc++-v3/ChangeLog:

	* include/bits/ranges_base.h
	(ranges::__access::__possibly_const_range): Mention LWG 4027.

diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h
index 28fe64a9e9da9ce7bcd9390e51a9a15ac394e581..516d04afdab263c4444488728a6dbdcb83bc6653 100644 (file)
--- a/libstdc++-v3/include/bits/ranges_base.h
+++ b/libstdc++-v3/include/bits/ranges_base.h
@@ -646,6 +646,8 @@ namespace ranges
       constexpr auto&
       __possibly_const_range(_Range& __r) noexcept
       {
+       // _GLIBCXX_RESOLVE_LIB_DEFECTS
+       // 4027. possibly-const-range should prefer returning const R&
        if constexpr (input_range<const _Range>)
          return const_cast<const _Range&>(__r);
        else