Index: include/bits/basic_string.h
===================================================================
--- include/bits/basic_string.h	(revision 201753)
+++ include/bits/basic_string.h	(working copy)
@@ -842,10 +842,11 @@
       reference
       operator[](size_type __pos)
       {
-        // allow pos == size() as v3 extension:
+        // Allow pos == size() both in C++98 mode, as v3 extension,
+	// and in C++11 mode.
 	_GLIBCXX_DEBUG_ASSERT(__pos <= size());
-        // but be strict in pedantic mode:
-	_GLIBCXX_DEBUG_PEDASSERT(__pos < size());
+        // In pedantic mode be strict in C++98 mode.
+	_GLIBCXX_DEBUG_PEDASSERT(__cplusplus >= 201103L || __pos < size());
 	_M_leak();
 	return _M_data()[__pos];
       }
Index: include/ext/vstring.h
===================================================================
--- include/ext/vstring.h	(revision 201753)
+++ include/ext/vstring.h	(working copy)
@@ -557,10 +557,12 @@
       reference
       operator[](size_type __pos)
       {
-        // allow pos == size() as v3 extension:
+        // Allow pos == size() both in C++98 mode, as v3 extension,
+	// and in C++11 mode.
 	_GLIBCXX_DEBUG_ASSERT(__pos <= this->size());
-        // but be strict in pedantic mode:
-	_GLIBCXX_DEBUG_PEDASSERT(__pos < this->size());
+        // In pedantic mode be strict in C++98 mode.
+	_GLIBCXX_DEBUG_PEDASSERT(__cplusplus >= 201103L
+				 || __pos < this->size());
 	this->_M_leak();
 	return this->_M_data()[__pos];
       }
Index: testsuite/21_strings/basic_string/element_access/char/58163.cc
===================================================================
--- testsuite/21_strings/basic_string/element_access/char/58163.cc	(revision 0)
+++ testsuite/21_strings/basic_string/element_access/char/58163.cc	(working copy)
@@ -0,0 +1,39 @@
+// 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-options "-std=gnu++11 -D_GLIBCXX_DEBUG_PEDANTIC" }
+
+#include <string>
+#include <testsuite_hooks.h>
+
+// PR c++/58163
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  const std::string cs;
+        std::string  s;
+
+  VERIFY( cs[0] == '\0' );
+  VERIFY(  s[0] == '\0' );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: testsuite/21_strings/basic_string/element_access/wchar_t/58163.cc
===================================================================
--- testsuite/21_strings/basic_string/element_access/wchar_t/58163.cc	(revision 0)
+++ testsuite/21_strings/basic_string/element_access/wchar_t/58163.cc	(working copy)
@@ -0,0 +1,39 @@
+// 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-options "-std=gnu++11 -D_GLIBCXX_DEBUG_PEDANTIC" }
+
+#include <string>
+#include <testsuite_hooks.h>
+
+// PR c++/58163
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  const std::wstring cs;
+        std::wstring  s;
+
+  VERIFY( cs[0] == L'\0' );
+  VERIFY(  s[0] == L'\0' );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: testsuite/ext/vstring/element_access/char/58163.cc
===================================================================
--- testsuite/ext/vstring/element_access/char/58163.cc	(revision 0)
+++ testsuite/ext/vstring/element_access/char/58163.cc	(working copy)
@@ -0,0 +1,40 @@
+// 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-options "-std=gnu++11 -D_GLIBCXX_DEBUG_PEDANTIC" }
+// { dg-require-string-conversions "" }
+
+#include <ext/vstring.h>
+#include <testsuite_hooks.h>
+
+// PR c++/58163
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  const __gnu_cxx::__vstring cs;
+        __gnu_cxx::__vstring  s;
+
+  VERIFY( cs[0] == '\0' );
+  VERIFY(  s[0] == '\0' );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: testsuite/ext/vstring/element_access/wchar_t/58163.cc
===================================================================
--- testsuite/ext/vstring/element_access/wchar_t/58163.cc	(revision 0)
+++ testsuite/ext/vstring/element_access/wchar_t/58163.cc	(working copy)
@@ -0,0 +1,40 @@
+// 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-options "-std=gnu++11 -D_GLIBCXX_DEBUG_PEDANTIC" }
+// { dg-require-string-conversions "" }
+
+#include <ext/vstring.h>
+#include <testsuite_hooks.h>
+
+// PR c++/58163
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  const __gnu_cxx::__wvstring cs;
+        __gnu_cxx::__wvstring  s;
+
+  VERIFY( cs[0] == L'\0' );
+  VERIFY(  s[0] == L'\0' );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
