John Maddock wrote:

All users of Boost.Regex-1.31.1 should be aware that there are now a set of patches available for this release - see https://sourceforge.net/project/showfiles.php?group_id=7586 for downloads.

Issues fixed include:

POSIX style regular expressions not behaving correctly with regex_grep. Non-greedy repeats not backtracking correctly in some cases. Backreferences cause some repeat operators to behave incorrectly. Some wide character expressions weren't getting correctly optimised, leading to thrown exceptions in trivial cases. Misc. compiler compatibility fixes.

Thanks, John. It is appreciated.