Why was regex (and other C++11 headers) unapproved?

[joelfrederico]

Why were several C++11 headers "unapproved" under the Google Style? I'm specifically interested in the regex header.

https://github.com/google/styleguide/blob/gh-pages/cpplint/cpplint.py#L5775

02af628

[joelfrederico]

Nevermind, I found it: https://chromium-cpp.appspot.com/

Apparently the Google team working on Chromium maintains cpplint and they don't like the regex header because they prefer re2: https://github.com/google/re2.