[Bug libstdc++/56166] std::string::clear() can throw despite being marked noexcept

[fasdfasdas at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56166

--- Comment #9 from Tolga <fasdfasdas at gmail dot com> ---
It was a bug in my code that called clear from one thread while other inserts
something.

Yet, it throws.