https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116942
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- The modified ECMAScript grammar in the C++ standard says: "If the CV of a UnicodeEscapeSequence is greater than the largest value that can be held in an object of type charT the translator shall throw an exception object of type regex_error." But that only means that when CHAR_MAX is 0x7f we can't use "\u0080", it doesn't help for "\x80" which ECMAScript says should mean the same thing. And as I said above, when char is unsigned this means "\u0080" is valid, but still doesn't actually work correctly. (You should just use Boost.Regex)
