[PATCH] PR libstdc++/86658 fix __niter_wrap to not copy invalid iterators

[Jonathan Wakely]

An output iterator passed as the unused first argument to __niter_wrap
might have already been invalidated, so don't copy it.

        PR libstdc++/86658
        * include/bits/stl_algobase.h (__niter_wrap<_Iterator>): Pass unused
        parameter by reference, to avoid copying invalid iterators.
        * testsuite/25_algorithms/copy/86658.cc: New test.

Tested powerpc64le-linux, committed to trunk.


commit e2dcaf432a8fa6e8e9d96b03003ece28fa3f1ca6
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Tue Jul 24 21:33:54 2018 +0100

    PR libstdc++/86658 fix __niter_wrap to not copy invalid iterators
    
    An output iterator passed as the unused first argument to __niter_wrap
    might have already been invalidated, so don't copy it.
    
            PR libstdc++/86658
            * include/bits/stl_algobase.h (__niter_wrap<_Iterator>): Pass unused
            parameter by reference, to avoid copying invalid iterators.
            * testsuite/25_algorithms/copy/86658.cc: New test.

diff --git a/libstdc++-v3/include/bits/stl_algobase.h 
b/libstdc++-v3/include/bits/stl_algobase.h
index f0130bc4123..b1ecd83ddb7 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -288,7 +288,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // No need to wrap, iterator already has the right type.
   template<typename _Iterator>
     inline _Iterator
-    __niter_wrap(_Iterator, _Iterator __res)
+    __niter_wrap(const _Iterator&, _Iterator __res)
     { return __res; }
 
   // All of these auxiliary structs serve two purposes.  (1) Replace
diff --git a/libstdc++-v3/testsuite/25_algorithms/copy/86658.cc 
b/libstdc++-v3/testsuite/25_algorithms/copy/86658.cc
new file mode 100644
index 00000000000..600747a823d
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/copy/86658.cc
@@ -0,0 +1,36 @@
+// Copyright (C) 2018 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 }
+
+#define _GLIBCXX_DEBUG
+#include <algorithm>
+#include <vector>
+
+void
+test01()
+{
+  int i[1] = { 1 };
+  std::vector<int> v(1);
+  std::copy(i, i+1, std::inserter(v, v.end()));
+}
+
+int
+main()
+{
+  test01();
+}