1. Historically, std::regex was offered in GCC before it was actually fully implemented. Much hilarity ensued... 2. Some existing implementations have efficien

1. Historically, std::regex was offered in GCC before it was actually fully implemented. Much hilarity ensued... 2. Some existing implementations have efficiency issues, e.g. performing many allocations. 3. It is claimed (e.g. by Titus Winters) that the ABI of std::regex is problematic, and without breaking it, the implementations cannot be good enough See these points and others at: https://www.reddit.com/r/cpp/comments/e16s1m/what_is_wrong_with_stdregex/ https://www.reddit.com/r/cpp/comments/e16s1m/what_is_wrong_w...