[Bug libstdc++/26887] New: const_reverse_iterator does not have a mixed equality or inequality operator

[schaudhu at blackrock dot com]

The behavior of const_reverse_iterator is different from the behavior of
const_iterator, due to having no mixed const/non-const equality or inequality
operators.  Consider the following code:

#include <map>
#include <iostream>

using std::map;
using std::cout;
using std::endl;
using std::string;


void test1()
{
    map< int, string > map1;
    map1[ 0 ] = "test1";
    map1[ 1 ] = "test2";

    typedef map< int, string >::const_iterator conit;

    // The following is okay because although map1.end()
    // returns a non-const iterator, const_iterator has a
    // mixed const/non-const inequality operator defined.
    for( conit cit = map1.begin() ; cit != map1.end() ; ++cit )
        cout << ( *cit ).second << endl;
}

void test3( const map< int, string > &map1 )
{
    typedef map< int, string >::const_reverse_iterator conit;

    // The following is okay, because map1.rend() returns
    // a const_reverse_iterator
    for( conit cit = map1.rbegin() ; cit != map1.rend() ; ++cit )
        cout << ( *cit ).second << endl;
}

void test2()
{
    map< int, string > map1;
    map1[ 0 ] = "test1";
    map1[ 1 ] = "test2";

    typedef map< int, string >::const_reverse_iterator conit;

    test3( map1 );

    // The following line fails to compile:
    // map1.rend() returns a non-const reverse_iterator
    // and there is no mixed inequality operator
    for( conit cit = map1.rbegin() ; cit != map1.rend() ; ++cit )
        cout << ( *cit ).second << endl;
}

int main()
{
    test1();
    test2();

    return 0;
}


-- 
           Summary: const_reverse_iterator does not have a mixed equality or
                    inequality operator
           Product: gcc
           Version: 3.3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: schaudhu at blackrock dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26887