Add std::copy_n __glibcxx_requires_can_increment checks.

	* include/bits/stl_algo.h (copy_n): Add __glibcxx_requires_can_increment
	debug checks.
	* testsuite/25_algorithms/copy_n/debug/1_neg.cc: New.
	* testsuite/25_algorithms/copy_n/debug/2_neg.cc: New.

From-SVN: r276636

libstdc++-v3/ChangeLog

+2019-10-06  François Dumont  <fdumont@gcc.gnu.org>
+
+	* include/bits/stl_algo.h (copy_n): Add __glibcxx_requires_can_increment
+	debug checks.
+	* testsuite/25_algorithms/copy_n/debug/1_neg.cc: New.
+	* testsuite/25_algorithms/copy_n/debug/2_neg.cc: New.
+
 2019-10-04  François Dumont  <fdumont@gcc.gnu.org>
 
 	* include/debug/forward_list

libstdc++-v3/include/bits/stl_algo.h

@@ -826,6 +826,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
       __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
 	    typename iterator_traits<_InputIterator>::value_type>)
+      __glibcxx_requires_can_increment(__first, __n);
+      __glibcxx_requires_can_increment(__result, __n);
 
       return std::__copy_n(__first, __n, __result,
 			   std::__iterator_category(__first));

libstdc++-v3/testsuite/25_algorithms/copy_n/debug/1_neg.cc

+// Copyright (C) 2019 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 { target c++11 xfail *-*-* } }
+// { dg-require-debug-mode "" }
+
+#include <algorithm>
+#include <vector>
+
+void
+test01()
+{
+  std::vector<int> v1(3, 1);
+  std::vector<int> v2(5, 0);
+
+  std::copy_n(v1.begin(), 5, v2.begin());
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}

libstdc++-v3/testsuite/25_algorithms/copy_n/debug/2_neg.cc

+// Copyright (C) 2019 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 { target c++11 xfail *-*-* } }
+// { dg-require-debug-mode "" }
+
+#include <algorithm>
+#include <vector>
+
+void
+test01()
+{
+  std::vector<int> v1(5, 1);
+  std::vector<int> v2(3, 0);
+
+  std::copy_n(v1.begin(), 5, v2.begin());
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}