[committed] libstdc++: Add missing move in ranges::copy

[Jonathan Wakely via Gcc-patches]

Tested x86_64-linux. Pushed to trunk.

-- >8 --

This is needed to support a move-only output iterator when the input
iterators are specializations of __normal_iterator.

libstdc++-v3/ChangeLog:

        * include/bits/ranges_algobase.h (__detail::__copy_or_move):
        Move output iterator.
        * testsuite/25_algorithms/copy/constrained.cc: Check copying to
        move-only output iterator.
---
 libstdc++-v3/include/bits/ranges_algobase.h   |  2 +-
 .../25_algorithms/copy/constrained.cc         | 24 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/bits/ranges_algobase.h 
b/libstdc++-v3/include/bits/ranges_algobase.h
index f6f0b9c83b0..443ad52ecc6 100644
--- a/libstdc++-v3/include/bits/ranges_algobase.h
+++ b/libstdc++-v3/include/bits/ranges_algobase.h
@@ -239,7 +239,7 @@ namespace ranges
        {
          auto [__in,__out]
            = ranges::__copy_or_move<_IsMove>(__first.base(), __last.base(),
-                                             __result);
+                                             std::move(__result));
          return {decltype(__first){__in}, std::move(__out)};
        }
       else if constexpr (__is_normal_iterator<_Out>)
diff --git a/libstdc++-v3/testsuite/25_algorithms/copy/constrained.cc 
b/libstdc++-v3/testsuite/25_algorithms/copy/constrained.cc
index 98f038a6c5f..444dfa78894 100644
--- a/libstdc++-v3/testsuite/25_algorithms/copy/constrained.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/copy/constrained.cc
@@ -226,6 +226,29 @@ test06()
   VERIFY( ranges::equal(v, (int[]){1,2,3,0}) );
 }
 
+void
+test07()
+{
+  struct move_only_output_iterator
+  {
+    using value_type = int;
+    using difference_type = short;
+    using iterator_category = std::output_iterator_tag;
+
+    move_only_output_iterator() = default;
+    move_only_output_iterator(move_only_output_iterator&&) = default;
+    move_only_output_iterator& operator=(move_only_output_iterator&&) = 
default;
+
+    move_only_output_iterator& operator*() { return *this; }
+    move_only_output_iterator& operator++() { return *this; }
+    move_only_output_iterator operator++(int) { return std::move(*this); }
+
+    void operator=(int) { }
+  };
+
+  ranges::copy(std::vector<int>{1,2,3}, move_only_output_iterator{});
+}
+
 int
 main()
 {
@@ -235,4 +258,5 @@ main()
   test04();
   static_assert(test05());
   test06();
+  test07();
 }
-- 
2.38.1