The change in r263433 broke the contract of the __rotate functions, by no
longer accepting empty ranges. That means that callers which inlined the
old version of std::rotate (without checks) that end up linking to a new
definition of std::__rotate (also without checks) could perform a divide
by zero and crash.
This restores the old contract of the __rotate overloads.
PR libstdc++/90920 partially revert r263433
* include/bits/stl_algo.h (__rotate): Restore checks for empty ranges.
(rotate): Remove checks.
* testsuite/25_algorithms/rotate/90920.cc: New test.
Tested x86_64-linux, committed to trunk.
This needs to be backported to gcc-9-branch too.
commit 100ba82c20a03d6ff316eb34fb46fe29e5c920fc
Author: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed Jun 19 22:57:02 2019 +0000
PR libstdc++/90920 restore previous checks for empty ranges
The change in r263433 broke the contract of the __rotate functions, by no
longer accepting empty ranges. That means that callers which inlined the
old version of std::rotate (without checks) that end up linking to a new
definition of std::__rotate (also without checks) could perform a divide
by zero and crash.
This restores the old contract of the __rotate overloads.
PR libstdc++/90920 partially revert r263433
* include/bits/stl_algo.h (__rotate): Restore checks for empty
ranges.
(rotate): Remove checks.
* testsuite/25_algorithms/rotate/90920.cc: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@272489
138bc75d-0d04-0410-961f-82ee72b054a4
diff --git a/libstdc++-v3/include/bits/stl_algo.h
b/libstdc++-v3/include/bits/stl_algo.h
index ca957e0b9a7..ac21c55ca1b 100644
--- a/libstdc++-v3/include/bits/stl_algo.h
+++ b/libstdc++-v3/include/bits/stl_algo.h
@@ -1251,6 +1251,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_ForwardIterator __last,
forward_iterator_tag)
{
+ if (__first == __middle)
+ return __last;
+ else if (__last == __middle)
+ return __first;
+
_ForwardIterator __first2 = __middle;
do
{
@@ -1291,6 +1296,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
_BidirectionalIterator>)
+ if (__first == __middle)
+ return __last;
+ else if (__last == __middle)
+ return __first;
+
std::__reverse(__first, __middle, bidirectional_iterator_tag());
std::__reverse(__middle, __last, bidirectional_iterator_tag());
@@ -1324,6 +1334,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
+ if (__first == __middle)
+ return __last;
+ else if (__last == __middle)
+ return __first;
+
typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_Distance;
typedef typename iterator_traits<_RandomAccessIterator>::value_type
@@ -1425,11 +1440,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__glibcxx_requires_valid_range(__first, __middle);
__glibcxx_requires_valid_range(__middle, __last);
- if (__first == __middle)
- return __last;
- else if (__last == __middle)
- return __first;
-
return std::__rotate(__first, __middle, __last,
std::__iterator_category(__first));
}
diff --git a/libstdc++-v3/testsuite/25_algorithms/rotate/90920.cc
b/libstdc++-v3/testsuite/25_algorithms/rotate/90920.cc
new file mode 100644
index 00000000000..cae3ae748d8
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/rotate/90920.cc
@@ -0,0 +1,48 @@
+// 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 }
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+
+namespace gnu_test
+{
+ // This is the definition from GCC 8.x, with no checks for first==middle
+ // or middle==last.
+ template<typename _ForwardIterator>
+ inline _ForwardIterator
+ rotate(_ForwardIterator __first, _ForwardIterator __middle,
+ _ForwardIterator __last)
+ {
+ return std::__rotate(__first, __middle, __last,
+ std::__iterator_category(__first));
+ }
+}
+
+void
+test01()
+{
+ int i = 0;
+ gnu_test::rotate(&i, &i, &i+1);
+}
+
+int
+main()
+{
+ test01();
+}
