From 9b574f1ece055ed1ad5ba32bc9ce570e9d9e2b29 Mon Sep 17 00:00:00 2001
From: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 1 Oct 2014 12:34:04 +0000
Subject: 	PR libstdc++/59603 	* include/bits/stl_algo.h
 (random_shuffle): Prevent self-swapping. 	*
 testsuite/25_algorithms/random_shuffle/59603.cc: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_9-branch@215754 138bc75d-0d04-0410-961f-82ee72b054a4
---
 libstdc++-v3/ChangeLog                             |  6 ++++
 libstdc++-v3/include/bits/stl_algo.h               | 13 +++++++--
 .../25_algorithms/random_shuffle/59603.cc          | 34 ++++++++++++++++++++++
 3 files changed, 51 insertions(+), 2 deletions(-)
 create mode 100644 libstdc++-v3/testsuite/25_algorithms/random_shuffle/59603.cc

(limited to 'libstdc++-v3')

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 813301c491a..00203680fcb 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,9 @@
+2014-10-01  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/59603
+	* include/bits/stl_algo.h (random_shuffle): Prevent self-swapping.
+	* testsuite/25_algorithms/random_shuffle/59603.cc: New.
+
 2014-09-11  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/63219
diff --git a/libstdc++-v3/include/bits/stl_algo.h b/libstdc++-v3/include/bits/stl_algo.h
index 4c6ca8a7268..cfb50a92884 100644
--- a/libstdc++-v3/include/bits/stl_algo.h
+++ b/libstdc++-v3/include/bits/stl_algo.h
@@ -4430,7 +4430,12 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 
       if (__first != __last)
 	for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
-	  std::iter_swap(__i, __first + (std::rand() % ((__i - __first) + 1)));
+	  {
+	    _RandomAccessIterator __j = __first
+					+ std::rand() % ((__i - __first) + 1);
+	    if (__i != __j)
+	      std::iter_swap(__i, __j);
+	  }
     }
 
   /**
@@ -4464,7 +4469,11 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       if (__first == __last)
 	return;
       for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
-	std::iter_swap(__i, __first + __rand((__i - __first) + 1));
+	{
+	  _RandomAccessIterator __j = __first + __rand((__i - __first) + 1);
+	  if (__i != __j)
+	    std::iter_swap(__i, __j);
+	}
     }
 
 
diff --git a/libstdc++-v3/testsuite/25_algorithms/random_shuffle/59603.cc b/libstdc++-v3/testsuite/25_algorithms/random_shuffle/59603.cc
new file mode 100644
index 00000000000..7b179ac19a0
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/random_shuffle/59603.cc
@@ -0,0 +1,34 @@
+// Copyright (C) 2014 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-options "-std=gnu++11" }
+// { dg-require-debug-mode "" }
+
+// libstdc++/59603
+
+#include <algorithm>
+#include <vector>
+
+struct C {
+    std::vector<int> v;
+    C (int a) : v{a} {};
+};
+
+int main () {
+    std::vector<C> cs { {1}, {2}, {3}, {4} };
+    std::random_shuffle(cs.begin(), cs.end());
+}
-- 
cgit v1.2.1