[gcc(refs/vendors/ARM/heads/arm-perf-staging)] libstdc++: decay in viewable_range should be remove_cvref (LWG 3375)

[Tamar Christina <tnfchris@gcc.gnu.org>]

https://gcc.gnu.org/g:26eae9ac2bf75a26a419dc1e47a067c66331fb74

commit 26eae9ac2bf75a26a419dc1e47a067c66331fb74
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Feb 6 11:30:30 2020 +0000

    libstdc++: decay in viewable_range should be remove_cvref (LWG 3375)
    
            * include/bits/stl_algobase.h (__iter_swap, __iter_swap<true>): Remove
            redundant _GLIBCXX20_CONSTEXPR.

Diff:
---
 libstdc++-v3/ChangeLog          | 3 +++
 libstdc++-v3/include/std/ranges | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 50c4dd9b84c..a9c96ac9185 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -3,6 +3,9 @@
 	* include/bits/stl_algobase.h (__iter_swap, __iter_swap<true>): Remove
 	redundant _GLIBCXX20_CONSTEXPR.
 
+	* include/std/ranges (viewable_range): Replace decay_t with
+	remove_cvref_t (LWG 3375).
+
 2020-02-05  Jonathan Wakely  <jwakely@redhat.com>
 
 	* include/bits/iterator_concepts.h (iter_reference_t)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index ea558c76c9d..860f7283be5 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -92,7 +92,7 @@ namespace ranges
   /// A range which can be safely converted to a view.
   template<typename _Tp>
     concept viewable_range = range<_Tp>
-      && (safe_range<_Tp> || view<decay_t<_Tp>>);
+      && (safe_range<_Tp> || view<remove_cvref_t<_Tp>>);
 
   namespace __detail
   {