--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libstdc++-v3/testsuite/25_algorithms/copy_backward/94013.cc	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,78 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do run }
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  volatile int i[2] = { 1, 2 };
+  volatile int j[2] = { 0, 0 };
+  int k[2] = { 0, 0 };
+
+  std::copy_backward(i, i+2, j+2);
+  VERIFY( j[0] == 1 && j[1] == 2 );
+  std::copy_backward(i, i+2, k+2);
+  VERIFY( k[0] == 1 && k[1] == 2 );
+  std::copy_backward(k+1, k+2, i+1);
+  VERIFY( i[0] == 2 );
+
+  const volatile int* cj = j;
+  std::copy_backward(cj, cj+2, i+2);
+  VERIFY( i[0] == 1 && i[1] == 2 );
+  std::copy_backward(cj+1, cj+2, k+1);
+  VERIFY( k[0] == 2 );
+  const int* ck = k;
+  std::copy_backward(ck, ck+2, i+2);
+  VERIFY( i[0] == 2 && i[1] == 2 );
+}
+
+void
+test02()
+{
+#if __cplusplus > 201703L
+  volatile int i[2] = { 1, 2 };
+  volatile int j[2] = { 0, 0 };
+  int k[2] = { 0, 0 };
+
+  std::ranges::copy_backward(i, i+2, j+2);
+  VERIFY( j[0] == 1 && j[1] == 2 );
+  std::ranges::copy_backward(i, i+2, k+2);
+  VERIFY( k[0] == 1 && k[1] == 2 );
+  std::ranges::copy_backward(k+1, k+2, i+1);
+  VERIFY( i[0] == 2 );
+
+  const volatile int* cj = j;
+  std::ranges::copy_backward(cj, cj+2, i+2);
+  VERIFY( i[0] == 1 && i[1] == 2 );
+  std::ranges::copy_backward(cj+1, cj+2, k+1);
+  VERIFY( k[0] == 2 );
+  const int* ck = k;
+  std::ranges::copy_backward(ck, ck+2, i+2);
+  VERIFY( i[0] == 2 && i[1] == 2 );
+#endif
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}