Created attachment 30929 [details]
Archive containing the g++ -v -save-temps compile log, the generated .ii file and the original .cpp with the minimum-to-reproduce test case.
I attempted to use a regex to validate qualified hostnames.
However, when I used the regex from this thread ( http://stackoverflow.com/questions/1418423/the-hostname-regex ), with or without replacing the [0-9A-Za-z] with [:alnum:] (and properly escaping the backslashes), I get a regex_error exception thrown on std::regex_match() call, with a regex_constants::error_brack as the reported code().
Using: An unmodified copy of gcc 4.8.1 20130603 from the Fedora 19 primary repository (rpm ver: 4.8.1-1.fc19 )
(I use 4-spaces-per-tab in my source code, which isn't relevant for the code, but might make hand-tracing of Parens, Braces, and Brackets I did in comments more understandable.)
(And, yes, I know replacing [0-9A-Za-z] with [:alnum:] isn't a legitimate change WRT domain name validity, unless I force a 'C' locale. It was just easier to read when hunting down this issue.)
Created attachment 30930 [details]
re-uploading my tar.gz -- fixed an independent but potentially distracting typo.
There was a case where part of the regex read "(?(?:" rather than "(?:(?:". Fixed that, behvior remains.
[:alnum:] only matches the six characters ":almnu". If you want to match any letter or digit you have to write [[:alnum:]].
<regex> doesn't work in GCC 4.8
Your test works with the GCC trunk, where the work to implement regex is being done.
*** This bug has been marked as a duplicate of bug 53631 ***
Date: Tue Oct 1 15:26:50 2013
New Revision: 203067
2013-10-01 Tim Shen <email@example.com>
* include/bits/regex_automaton.tcc (_NFA<>::_M_eliminate_dummy)
(_StateSeq<>::_M_clone): Add _S_opcode_subexpr_lookahead branch.
* testsuite/28_regex/algorithms/regex_match/ecma/char/58576.cc: New.