[v3] Fix libstdc++/15523

[Paolo Carlini <paolo dot carlini at oracle dot com>]

Hi,

tested x86_64-linux, committed to mainline.

Paolo.

///////////////////

2009-08-04  Paolo Carlini  <paolo.carlini@oracle.com>

	PR libstdc++/15523
	* include/debug/safe_iterator.h (_Safe_iterator<>::
	_Safe_iterator(const _Safe_iterator&), _Safe_iterator<>::
	operator=(const _Safe_iterator&)): Implement resolution of DR 408,
	do not error out when the source is a value-initialized iterator.
	* testsuite/23_containers/vector/15523.cc: New.
	* doc/xml/manual/intro.xml: Add an entry for DR 408.

Index: doc/xml/manual/intro.xml
===================================================================
--- doc/xml/manual/intro.xml	(revision 150408)
+++ doc/xml/manual/intro.xml	(working copy)
@@ -604,6 +604,14 @@
     <listitem><para>Replace &quot;new&quot; with &quot;::new&quot;.
     </para></listitem></varlistentry>
 
+    <varlistentry><term><ulink url="../ext/lwg-active.html#408">408</ulink>:
+        <emphasis>
+        Is vector&lt;reverse_iterator&lt;char*&gt; &gt; forbidden?
+        </emphasis>
+    </term>
+    <listitem><para>Tweak the debug-mode checks in _Safe_iterator.
+    </para></listitem></varlistentry>
+
     <varlistentry><term><ulink url="../ext/lwg-defects.html#409">409</ulink>:
         <emphasis>Closing an fstream should clear the error state</emphasis>
     </term>
Index: include/debug/safe_iterator.h
===================================================================
--- include/debug/safe_iterator.h	(revision 150408)
+++ include/debug/safe_iterator.h	(working copy)
@@ -115,12 +115,14 @@
 
       /**
        * @brief Copy construction.
-       * @pre @p x is not singular
        */
       _Safe_iterator(const _Safe_iterator& __x)
       : _Safe_iterator_base(__x, _M_constant()), _M_current(__x._M_current)
       {
-	_GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
+	// _GLIBCXX_RESOLVE_LIB_DEFECTS
+	// DR 408. Is vector<reverse_iterator<char*> > forbidden?
+	_GLIBCXX_DEBUG_VERIFY(!__x._M_singular()
+			      || __x._M_current == _Iterator(),
 			      _M_message(__msg_init_copy_singular)
 			      ._M_iterator(*this, "this")
 			      ._M_iterator(__x, "other"));
@@ -129,8 +131,6 @@
       /**
        *  @brief Converting constructor from a mutable iterator to a
        *  constant iterator.
-       *
-       *  @pre @p x is not singular
       */
       template<typename _MutableIterator>
         _Safe_iterator(
@@ -140,7 +140,10 @@
                    _Sequence>::__type>& __x)
 	: _Safe_iterator_base(__x, _M_constant()), _M_current(__x.base())
         {
-	  _GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
+	  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+	  // DR 408. Is vector<reverse_iterator<char*> > forbidden?
+	  _GLIBCXX_DEBUG_VERIFY(!__x._M_singular()
+				|| __x.base() == _Iterator(),
 				_M_message(__msg_init_const_singular)
 				._M_iterator(*this, "this")
 				._M_iterator(__x, "other"));
@@ -148,12 +151,14 @@
 
       /**
        * @brief Copy assignment.
-       * @pre @p x is not singular
        */
       _Safe_iterator&
       operator=(const _Safe_iterator& __x)
       {
-	_GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
+	// _GLIBCXX_RESOLVE_LIB_DEFECTS
+	// DR 408. Is vector<reverse_iterator<char*> > forbidden?
+	_GLIBCXX_DEBUG_VERIFY(!__x._M_singular()
+			      || __x._M_current == _Iterator(),
 			      _M_message(__msg_copy_singular)
 			      ._M_iterator(*this, "this")
 			      ._M_iterator(__x, "other"));
@@ -169,7 +174,6 @@
       reference
       operator*() const
       {
-
 	_GLIBCXX_DEBUG_VERIFY(this->_M_dereferenceable(),
 			      _M_message(__msg_bad_deref)
 			      ._M_iterator(*this, "this"));
Index: testsuite/23_containers/vector/15523.cc
===================================================================
--- testsuite/23_containers/vector/15523.cc	(revision 0)
+++ testsuite/23_containers/vector/15523.cc	(revision 0)
@@ -0,0 +1,39 @@
+// Copyright (C) 2009 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 "-D_GLIBCXX_DEBUG" }
+
+#include <vector> 
+
+// libstdc++/15523
+void test01() 
+{
+  using namespace std;
+
+  vector<vector<int>::const_iterator> x(2); 
+
+  vector<int>::iterator i2, i3;
+  vector<int>::const_iterator ci1(i2);
+
+  i2 = i3;
+} 
+
+int main()
+{
+  test01();
+  return 0;
+}