+*** 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: