re PR libstdc++/78389 (list::merge and list::sort are not exception safe)

PR libstdc++/78389
* include/bits/list.tcc (merge(list&&)):
Adjust list sizes if the comparator throws.
(merge(list&&, _StrictWeakOrdering)): Likewise.
(sort()): Splice elements back from the scratch buffers
if the comparator throws.
(sort(_StrictWeakOrdering)): Likewise.
* testsuite/23_containers/list/operations/78389.cc: New.

From-SVN: r244439

libstdc++-v3/ChangeLog

+2017-01-13  Ville Voutilainen  <ville.voutilainen@gmail.com>
+
+	PR libstdc++/78389
+	* include/bits/list.tcc (merge(list&&)):
+	Adjust list sizes if the comparator throws.
+	(merge(list&&, _StrictWeakOrdering)): Likewise.
+	(sort()): Splice elements back from the scratch buffers
+	if the comparator throws.
+	(sort(_StrictWeakOrdering)): Likewise.
+	* testsuite/23_containers/list/operations/78389.cc: New.
+
 2017-01-13  Jonathan Wakely  <jwakely@redhat.com>
 
 	* testsuite/23_containers/unordered_set/allocator/ext_ptr.cc: Mark

libstdc++-v3/include/bits/list.tcc

@@ -386,6 +386,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	  iterator __last1 = end();
 	  iterator __first2 = __x.begin();
 	  iterator __last2 = __x.end();
+	  const size_t __orig_size = __x.size();
+	  __try {
 	    while (__first1 != __last1 && __first2 != __last2)
 	      if (*__first2 < *__first1)
 		{
@@ -401,6 +403,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	    this->_M_inc_size(__x._M_get_size());
 	    __x._M_set_size(0);
 	  }
+	  __catch(...)
+	    {
+	      size_t __dist = std::distance(__first2, __last2);
+	      this->_M_inc_size(__dist);
+	      __x._M_set_size(__orig_size - __dist);
+	      __throw_exception_again;
+	    }
+	}
     }
 
   template<typename _Tp, typename _Alloc>
@@ -423,6 +433,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	    iterator __last1 = end();
 	    iterator __first2 = __x.begin();
 	    iterator __last2 = __x.end();
+	    const size_t __orig_size = __x.size();
+	    __try
+	      {
 		while (__first1 != __last1 && __first2 != __last2)
 		  if (__comp(*__first2, *__first1))
 		    {
@@ -438,6 +451,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 		this->_M_inc_size(__x._M_get_size());
 		__x._M_set_size(0);
 	      }
+	    __catch(...)
+	      {
+		size_t __dist = std::distance(__first2, __last2);
+		this->_M_inc_size(__dist);
+		__x._M_set_size(__orig_size - __dist);
+		__throw_exception_again;
+	      }
+	  }
       }
 
   template<typename _Tp, typename _Alloc>
@@ -453,7 +474,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
         list __tmp[64];
         list * __fill = __tmp;
         list * __counter;
-
+	__try
+	  {
 	    do
 	      {
 		__carry.splice(__carry.begin(), *this, begin());
@@ -475,6 +497,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	      __counter->merge(*(__counter - 1));
 	    swap( *(__fill - 1) );
 	  }
+	__catch(...)
+	  {
+	    this->splice(this->end(), __carry);
+	    for (int i = 0; i < sizeof(__tmp)/sizeof(__tmp[0]); ++i)
+	      this->splice(this->end(), __tmp[i]);
+	    __throw_exception_again;
+	  }
+      }
     }
 
   template<typename _Tp, typename _Alloc>
@@ -530,7 +560,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	    list __tmp[64];
 	    list * __fill = __tmp;
 	    list * __counter;
-
+	    __try
+	      {
 		do
 		  {
 		    __carry.splice(__carry.begin(), *this, begin());
@@ -552,6 +583,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 		  __counter->merge(*(__counter - 1), __comp);
 		swap(*(__fill - 1));
 	      }
+	    __catch(...)
+	      {
+		this->splice(this->end(), __carry);
+		for (int i = 0; i < sizeof(__tmp)/sizeof(__tmp[0]); ++i)
+		  this->splice(this->end(), __tmp[i]);
+		__throw_exception_again;
+	      }
+	  }
       }
 
 _GLIBCXX_END_NAMESPACE_CONTAINER

libstdc++-v3/testsuite/23_containers/list/operations/78389.cc

+// { dg-do run { target c++11 } }
+
+// 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/>.
+
+// 23.2.2.4 list operations [lib.list.ops]
+
+#include <testsuite_hooks.h>
+
+#include <list>
+
+struct ThrowingComparator
+{
+  unsigned int throw_after = 0;
+  unsigned int count = 0;
+  bool operator()(int, int) {
+    if (++count >= throw_after) {
+      throw 666;
+    }
+    return true;
+  }
+};
+
+struct X
+{
+  X() = default;
+  X(int) {}
+};
+
+unsigned int throw_after_X = 0;
+unsigned int count_X = 0;
+
+bool operator<(const X&, const X&) {
+  if (++count_X >= throw_after_X) {
+    throw 666;
+  }
+  return true;
+}
+
+
+int main()
+{
+  std::list<int> a{1, 2, 3, 4};
+  std::list<int> b{5, 6, 7, 8, 9, 10, 11, 12};
+  try {
+    a.merge(b, ThrowingComparator{5});
+  } catch (...) {
+  }
+  VERIFY(a.size() == 8 && b.size() == 4);
+  std::list<X> ax{1, 2, 3, 4};
+  std::list<X> bx{5, 6, 7, 8, 9, 10, 11, 12};
+  throw_after_X = 5;
+  try {
+    ax.merge(bx);
+  } catch (...) {
+  }
+  VERIFY(ax.size() == 8 && bx.size() == 4);
+  std::list<int> ay{5, 6, 7, 8, 9, 10, 11, 12};
+  try {
+    ay.sort(ThrowingComparator{5});
+  } catch (...) {
+  }
+  VERIFY(ay.size() == 8);
+  std::list<X> az{5, 6, 7, 8, 9, 10, 11, 12};
+  throw_after_X = 5;
+  try {
+    az.sort();
+  } catch (...) {
+  }
+  VERIFY(az.size() == 8);
+}