https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64649
Bug ID: 64649 Summary: regex_traits::lookup_classname() only works with random access iterators Product: gcc Version: 4.9.3 Status: UNCONFIRMED Keywords: rejects-valid Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: redi at gcc dot gnu.org #include <regex> #include <forward_list> int main() { std::forward_list<char> f{ 'A' }; std::regex_traits<char>{}.lookup_collatename(f.begin(), f.end()); } This function should work with ForwardIterators, but it fails because of line 300 in bits/regex.tcc std::string __s(__last - __first, '?');