*** boost/regex/v4/basic_regex_parser.hpp.orig	2008-01-14 12:53:01.000000000 -0600

--- boost/regex/v4/basic_regex_parser.hpp	2008-01-14 12:57:25.000000000 -0600

*************** bool basic_regex_parser<charT, traits>::

*** 777,782 ****

--- 777,783 ----

        case syntax_element_restart_continue:

        case syntax_element_jump:

        case syntax_element_startmark:

+       case syntax_element_backstep:

           // can't legally repeat any of the above:

           fail(regex_constants::error_badrepeat, m_position - m_base);

           return false;

*************** bool basic_regex_parser<charT, traits>::

*** 1862,1867 ****

--- 1863,1869 ----

     if(markid == -4)

     {

        re_syntax_base* b = this->getaddress(expected_alt_point);

+       // Make sure we have exactly one alternative following this state:

        if(b->type != syntax_element_alt)

        {

           re_alt* alt = static_cast<re_alt*>(this->insert_state(expected_alt_point, syntax_element_alt, sizeof(re_alt)));

*************** bool basic_regex_parser<charT, traits>::

*** 1872,1877 ****

--- 1874,1888 ----

           fail(regex_constants::error_bad_pattern, m_position - m_base);

           return false;

        }

+       // check for invalid repetition of next state:

+       b = this->getaddress(expected_alt_point);

+       b = this->getaddress(static_cast<re_alt*>(b)->next.i, b);

+       if((b->type != syntax_element_assert_backref)

+          && (b->type != syntax_element_startmark))

+       {

+          fail(regex_constants::error_badrepeat, m_position - m_base);

+          return false;

+       }

     }

     //

     // append closing parenthesis state: