Re: PR 57779 New debug check

[François Dumont <frs dot dumont at gmail dot com>]

On 07/11/2013 11:13 PM, Jonathan Wakely wrote:
> On 11 July 2013 21:49, Jonathan Wakely wrote:
> > On 11 July 2013 21:16, François Dumont wrote:
> > >      I am indeed dereferencing the end iterator but as long as it is just to
> > > get the address of the resulting element it is fine.
> > I don't think that's what the standard says.
> >
> > C99 and later say that &*p is OK if p is a null pointer, but C++ does
> > not have the same rule, see e.g.
> > http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#232 for an
> > open issue on this topic.  Even if that proposed resolution were to be
> > accepted (very unlikely, it's sat untouched for many years) what
> > you're doing is not the same, because you dereference an iterator
> > which returns a reference, and _then_ you take the address, so it's
> > equivalent to:
> >
> > T& end() { T* p = 0; return *p; }
> > T* p = &end();
> >
> > That forms an invalid reference before taking the address, so is not
> > the same as &*(T*)0, it's more like &(T&)*(T*)0 and I'm uncomfortable
> > with that.
> ... but willing to be convinced if I'm wrong :-)
Even if I still don't see what can goes wrong here I agree that in 
theory this is bad so here is another proposal that do not have this 
drawback. I also consider all your remarks I think except the Paolo 
remark about using std::greater. If I am playing with plain pointers why 
would I need to use std::less or std::greater ?

I also introduced a small helper to assert only when GNU extension is 
not making the call valid.

For set/map/unordered_set/unordered_map the call is fine because 
elements are not going to be inserted again so it is a no-op but I 
prefer to keep the debug assertion in this case because this is quite a 
useless operation that users better avoid.

François

Index: include/debug/macros.h
===================================================================
--- include/debug/macros.h	(revision 200963)
+++ include/debug/macros.h	(working copy)
@@ -72,11 +72,11 @@
 */
 #define __glibcxx_check_insert(_Position)				\
 _GLIBCXX_DEBUG_VERIFY(!_Position._M_singular(),				\
-		      _M_message(__gnu_debug::__msg_insert_singular) \
+		      _M_message(__gnu_debug::__msg_insert_singular)	\
 		      ._M_sequence(*this, "this")			\
 		      ._M_iterator(_Position, #_Position));		\
 _GLIBCXX_DEBUG_VERIFY(_Position._M_attached_to(this),			\
-		      _M_message(__gnu_debug::__msg_insert_different) \
+		      _M_message(__gnu_debug::__msg_insert_different)	\
 		      ._M_sequence(*this, "this")			\
 		      ._M_iterator(_Position, #_Position))
 
@@ -101,15 +101,16 @@
  *  that it reference the sequence we are inserting into, and that the
  *  iterator range [_First, Last) is a valid (possibly empty)
  *  range. Note that this macro is only valid when the container is a
- *  _Safe_sequence and the iterator is a _Safe_iterator.
- *
- *  @todo We would like to be able to check for noninterference of
- *  _Position and the range [_First, _Last), but that can't (in
- *  general) be done.
+ *  _Safe_sequence and the _Position iterator is a _Safe_iterator.
 */
 #define __glibcxx_check_insert_range(_Position,_First,_Last)		\
 __glibcxx_check_valid_range(_First,_Last);				\
-__glibcxx_check_insert(_Position)
+__glibcxx_check_insert(_Position);					\
+_GLIBCXX_DEBUG_VERIFY(__gnu_debug::__foreign_iterator(_Position,_First),\
+		      _M_message(__gnu_debug::__msg_insert_range_from_self)\
+		      ._M_iterator(_First, #_First)			\
+		      ._M_iterator(_Last, #_Last)			\
+		      ._M_sequence(*this, "this"))
 
 /** Verify that we can insert the values in the iterator range
  *  [_First, _Last) into *this after the iterator _Position.  Insertion
@@ -332,7 +333,7 @@
 		      _M_message(__gnu_debug::__msg_valid_load_factor)	\
                       ._M_sequence(*this, "this"))
 
-#define __glibcxx_check_equal_allocs(_Other)			\
+#define __glibcxx_check_equal_allocs(_Other)				\
 _GLIBCXX_DEBUG_VERIFY(this->get_allocator() == _Other.get_allocator(),	\
 		      _M_message(__gnu_debug::__msg_equal_allocs)	\
 		      ._M_sequence(*this, "this"))
Index: include/debug/list
===================================================================
--- include/debug/list	(revision 200963)
+++ include/debug/list	(working copy)
@@ -791,4 +791,11 @@
 } // namespace __debug
 } // namespace std
 
+namespace __gnu_debug
+{
+  template<class _Tp, class _Alloc>
+    struct _Insert_range_from_self_is_safe<std::__debug::list<_Tp, _Alloc> >
+    { enum { __value = 1 }; };
+}
+
 #endif
Index: include/debug/formatter.h
===================================================================
--- include/debug/formatter.h	(revision 200963)
+++ include/debug/formatter.h	(working copy)
@@ -114,7 +114,9 @@
     // unordered container buckets
     __msg_bucket_index_oob,
     __msg_valid_load_factor,
-    __msg_equal_allocs
+    // others
+    __msg_equal_allocs,
+    __msg_insert_range_from_self
   };
 
   class _Error_formatter
Index: include/debug/functions.h
===================================================================
--- include/debug/functions.h	(revision 200963)
+++ include/debug/functions.h	(working copy)
@@ -40,6 +40,10 @@
   template<typename _Iterator, typename _Sequence>
     class _Safe_iterator;
 
+  template<typename _Sequence>
+    struct _Insert_range_from_self_is_safe
+    { enum { __value = 0 }; };
+
   // An arbitrary iterator pointer is not singular.
   inline bool
   __check_singular_aux(const void*) { return false; }
@@ -162,6 +166,104 @@
       return __first;
     }
 
+  template<typename _Iterator, typename _Sequence, typename _InputIterator>
+    inline bool
+    __foreign_iterator_aux3(const _Safe_iterator<_Iterator, _Sequence>& __it,
+			    _InputIterator __other,
+			    std::__true_type)
+    {
+      // Only containers with all elements in contiguous memory can have their
+      // elements passed through pointers.
+      // Arithmetics is here just to make sure we are not dereferencing
+      // past-the-end iterator.
+      if (__it._M_get_sequence()->_M_base().begin()
+	  != __it._M_get_sequence()->_M_base().end())
+	if (std::__addressof(*(__it._M_get_sequence()->_M_base().end() - 1))
+	    - std::__addressof(*(__it._M_get_sequence()->_M_base().begin()))
+	    == __it._M_get_sequence()->size() - 1)
+	  return
+	    std::__addressof(*__other)
+	    < std::__addressof(*(__it._M_get_sequence()->_M_base().begin()))
+	    || std::__addressof(*__other)
+	    >= (std::__addressof(*(__it._M_get_sequence()->_M_base().end() - 1)) + 1);
+
+      return true;
+    }
+			   
+  /* Fallback overload for which we can't say, assume it is valid. */
+  template<typename _Iterator, typename _Sequence, typename _InputIterator>
+    inline bool
+    __foreign_iterator_aux3(const _Safe_iterator<_Iterator, _Sequence>& __it,
+			    _InputIterator __other,
+			    std::__false_type)
+    { return true; }
+			   
+  /** Checks that iterators do not belong to the same sequence. */
+  template<typename _Iterator, typename _Sequence, typename _OtherIterator>
+    inline bool
+    __foreign_iterator_aux2(const _Safe_iterator<_Iterator, _Sequence>& __it,
+		const _Safe_iterator<_OtherIterator, _Sequence>& __other,
+		std::input_iterator_tag)
+    {
+      return
+#ifndef _GLIBCXX_DEBUG_PEDANTIC
+	_Insert_range_from_self_is_safe<_Sequence>::__value ||
+#endif
+	__it._M_get_sequence() != __other._M_get_sequence();
+    }
+			   
+  /* This overload detects when passing pointers to the contained elements rather
+     than using iterators.
+   */
+  template<typename _Iterator, typename _Sequence, typename _InputIterator>
+    inline bool
+    __foreign_iterator_aux2(const _Safe_iterator<_Iterator, _Sequence>& __it,
+			    _InputIterator __other,
+			    std::random_access_iterator_tag)
+    {
+      typedef typename _Sequence::const_iterator _ItType;
+      typedef typename std::iterator_traits<_ItType>::reference _Ref;
+      return __foreign_iterator_aux3(__it, __other,
+				     std::__is_lvalue_reference<_Ref>());
+    }
+			   
+  /* Fallback overload for which we can't say, assume it is valid. */
+  template<typename _Iterator, typename _Sequence, typename _InputIterator>
+    inline bool
+    __foreign_iterator_aux2(const _Safe_iterator<_Iterator, _Sequence>&,
+			   _InputIterator,
+			   std::input_iterator_tag)
+    { return true; }
+			   
+  template<typename _Iterator, typename _Sequence,
+	   typename _Integral>
+    inline bool
+    __foreign_iterator_aux(const _Safe_iterator<_Iterator, _Sequence>& __it,
+			   _Integral __other,
+			   std::__true_type)
+    { return true; }
+
+  template<typename _Iterator, typename _Sequence,
+	   typename _InputIterator>
+    inline bool
+    __foreign_iterator_aux(const _Safe_iterator<_Iterator, _Sequence>& __it,
+			   _InputIterator __other,
+			   std::__false_type)
+    {
+      return __foreign_iterator_aux2(__it, __other,
+				     std::__iterator_category(__it));
+    }
+
+  template<typename _Iterator, typename _Sequence,
+	   typename _InputIterator>
+    inline bool
+    __foreign_iterator(const _Safe_iterator<_Iterator, _Sequence>& __it,
+		       _InputIterator __other)
+    {
+      typedef typename std::__is_integer<_InputIterator>::__type _Integral;
+      return __foreign_iterator_aux(__it, __other, _Integral());
+    }
+
   /** Checks that __s is non-NULL or __n == 0, and then returns __s. */
   template<typename _CharT, typename _Integer>
     inline const _CharT*
Index: include/debug/forward_list
===================================================================
--- include/debug/forward_list	(revision 200963)
+++ include/debug/forward_list	(working copy)
@@ -796,6 +796,11 @@
       _S_Is_Beginnest(_BaseIt __it, const _Sequence* __seq)
       { return _S_Is(__it, __seq); }
     };
+
+  template<class _Tp, class _Alloc>
+    struct _Insert_range_from_self_is_safe<
+      std::__debug::forward_list<_Tp, _Alloc> >
+      { enum { __value = 1 }; };
 }
 
 #endif
Index: testsuite/util/debug/checks.h
===================================================================
--- testsuite/util/debug/checks.h	(revision 200963)
+++ testsuite/util/debug/checks.h	(working copy)
@@ -129,7 +129,7 @@
       c2.assign(last, first); // Expected failure
     }
 
-  // Check that invalid range of debug !random debug iterators is detected
+  // Check that invalid range of debug not random iterators is detected
   template<typename _Tp>
     void
     check_assign3()
@@ -377,6 +377,34 @@
     }
 
   template<typename _Tp>
+    void
+    check_insert4()
+    {
+      bool test __attribute__((unused)) = true;
+
+      typedef _Tp cont_type;
+      typedef typename cont_type::value_type cont_val_type;
+      typedef typename CopyableValueType<cont_val_type>::value_type val_type;
+      typedef std::list<val_type> list_type;
+
+      generate_unique<val_type> gu;
+
+      list_type l;
+      for (int i = 0; i != 5; ++i)
+        l.push_back(gu.build());
+      VERIFY(l.size() == 5);
+
+      typename list_type::iterator first = l.begin(); ++first;
+      typename list_type::iterator last = first; ++last; ++last;
+
+      cont_type c1;
+      InsertRangeHelper<cont_type>::Insert(c1, l.begin(), l.end());
+      VERIFY(c1.size() == 5);
+
+      c1.insert(c1.begin(), c1.begin(), c1.end()); // Expected failure.
+    }
+
+  template<typename _Tp>
     void use_invalid_iterator()
     {
       bool test __attribute__((unused)) = true;
Index: testsuite/23_containers/vector/debug/insert5_neg.cc
===================================================================
--- testsuite/23_containers/vector/debug/insert5_neg.cc	(revision 0)
+++ testsuite/23_containers/vector/debug/insert5_neg.cc	(revision 0)
@@ -0,0 +1,33 @@
+// Copyright (C) 2013 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-require-debug-mode "" }
+// { dg-do run { xfail *-*-* } }
+
+#include <vector>
+#include <debug/checks.h>
+
+void test01()
+{
+  __gnu_test::check_insert4<std::vector<int> >();
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: testsuite/23_containers/vector/debug/insert6_neg.cc
===================================================================
--- testsuite/23_containers/vector/debug/insert6_neg.cc	(revision 0)
+++ testsuite/23_containers/vector/debug/insert6_neg.cc	(revision 0)
@@ -0,0 +1,48 @@
+// Copyright (C) 2013 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-require-debug-mode "" }
+// { dg-do run { xfail *-*-* } }
+
+#include <debug/vector>
+#include <debug/checks.h>
+
+void test01()
+{
+  std::vector<bool> v;
+  __gnu_debug::vector<bool> dv;
+  for (int i = 0; i != 10; ++i)
+    {
+      v.push_back((i % 2) != 0);
+      dv.push_back((i % 2) == 0);
+    }
+
+  dv.insert(dv.begin(), v.begin(), v.begin() + 5);
+  VERIFY( dv.size() == 15 );
+}
+
+void test02()
+{
+  __gnu_test::check_insert4<__gnu_debug::vector<bool> >();
+}
+
+int main()
+{
+  test01();
+  test02();
+  return 0;
+}
Index: testsuite/23_containers/vector/debug/57779_neg.cc
===================================================================
--- testsuite/23_containers/vector/debug/57779_neg.cc	(revision 0)
+++ testsuite/23_containers/vector/debug/57779_neg.cc	(revision 0)
@@ -0,0 +1,37 @@
+// Copyright (C) 2013 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-require-debug-mode "" }
+// { dg-do run { xfail *-*-* } }
+
+#include <vector>
+#include <debug/checks.h>
+
+void test01()
+{
+  std::vector<int> v;
+  for (int i = 0; i != 10; ++i)
+    v.push_back(i);
+
+  v.insert(v.begin(), v.data() + 1, v.data() + 5); // Expected failure
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: testsuite/23_containers/deque/debug/insert5_neg.cc
===================================================================
--- testsuite/23_containers/deque/debug/insert5_neg.cc	(revision 0)
+++ testsuite/23_containers/deque/debug/insert5_neg.cc	(revision 0)
@@ -0,0 +1,33 @@
+// Copyright (C) 2013 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-require-debug-mode "" }
+// { dg-do run { xfail *-*-* } }
+
+#include <deque>
+#include <debug/checks.h>
+
+void test01()
+{
+  __gnu_test::check_insert4<std::deque<int> >();
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: testsuite/23_containers/list/debug/insert5_neg.cc
===================================================================
--- testsuite/23_containers/list/debug/insert5_neg.cc	(revision 0)
+++ testsuite/23_containers/list/debug/insert5_neg.cc	(revision 0)
@@ -0,0 +1,34 @@
+// Copyright (C) 2013 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-require-debug-mode "" }
+// { dg-options "-D_GLIBCXX_DEBUG_PEDANTIC" }
+// { dg-do run { xfail *-*-* } }
+
+#include <list>
+#include <debug/checks.h>
+
+void test01()
+{
+  __gnu_test::check_insert4<std::list<int> >();
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: src/c++11/debug.cc
===================================================================
--- src/c++11/debug.cc	(revision 200963)
+++ src/c++11/debug.cc	(working copy)
@@ -181,7 +181,8 @@
     "attempt to access container with out-of-bounds bucket index %2;,"
     " container only holds %3; buckets",
     "load factor shall be positive",
-    "allocators must be equal"
+    "allocators must be equal",
+    "attempt to insert with an iterator range [%1.name;, %2.name;) from this container"
   };
 
   void
@@ -695,7 +696,7 @@
 	      }
 	    
 	    __formatter->_M_format_word(__buf, __bufsize, "@ 0x%p\n", 
-					_M_variant._M_sequence._M_address);
+					_M_variant._M_iterator._M_sequence);
 	    __formatter->_M_print_word(__buf);
 	  }
 	__formatter->_M_print_word("}\n");
@@ -808,8 +809,11 @@
     if (__length == 0)
       return;
     
-    if ((_M_column + __length < _M_max_length)
-	|| (__length >= _M_max_length && _M_column == 1)) 
+    size_t __visual_length
+      = __word[__length - 1] == '\n' ? __length - 1 : __length;
+    if (__visual_length == 0
+	|| (_M_column + __visual_length < _M_max_length)
+	|| (__visual_length >= _M_max_length && _M_column == 1)) 
       {
 	// If this isn't the first line, indent
 	if (_M_column == 1 && !_M_first_line)
@@ -823,17 +827,17 @@
 	  }
 	
 	fprintf(stderr, "%s", __word);
-	_M_column += __length;
 	
 	if (__word[__length - 1] == '\n') 
 	  {
 	    _M_first_line = false;
 	    _M_column = 1;
 	  }
+	else
+	  _M_column += __length;
       }
     else
       {
-	_M_column = 1;
 	_M_print_word("\n");
 	_M_print_word(__word);
       }