[PATCH] PR64903 fix number of predicate tests in std::is_partitioned

[Jonathan Wakely]

        PR libstdc++/64903
        * include/bits/stl_algo.h (is_partioned): Don't retest the partition
        point.
        * testsuite/25_algorithms/is_partitioned/2.cc: New test.

Tested powerpc64le-linux, committed to trunk.


commit 5e9b690d27ac3cecf138bac904606f5728ca452f
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Thu Jan 19 23:26:09 2017 +0000

    PR64903 fix number of predicate tests in std::is_partitioned
    
        PR libstdc++/64903
        * include/bits/stl_algo.h (is_partioned): Don't retest the partition
        point.
        * testsuite/25_algorithms/is_partitioned/2.cc: New test.

diff --git a/libstdc++-v3/include/bits/stl_algo.h 
b/libstdc++-v3/include/bits/stl_algo.h
index fadcf7b..8cf85aa02f 100644
--- a/libstdc++-v3/include/bits/stl_algo.h
+++ b/libstdc++-v3/include/bits/stl_algo.h
@@ -583,6 +583,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                   _Predicate __pred)
     {
       __first = std::find_if_not(__first, __last, __pred);
+      if (__first == __last)
+       return true;
+      std::advance(__first, 1);
       return std::none_of(__first, __last, __pred);
     }
 
diff --git a/libstdc++-v3/testsuite/25_algorithms/is_partitioned/2.cc 
b/libstdc++-v3/testsuite/25_algorithms/is_partitioned/2.cc
new file mode 100644
index 0000000..4b027cc
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/is_partitioned/2.cc
@@ -0,0 +1,45 @@
+// Copyright (C) 2017 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 } }
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+
+// PR libstdc++/64903
+
+int count;
+
+struct pred
+{
+  bool operator()(int i) const { ++count; return i < 5; }
+};
+
+void
+test01()
+{
+  int i[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+  bool result = std::is_partitioned(i, i + 10, pred());
+  VERIFY( result );
+  VERIFY( count == 10 );
+}
+
+int
+main()
+{
+  test01();
+}