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

[zackw at panix dot com]

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

--- Comment #4 from Zack Weinberg <zackw at panix dot com> 2013-02-01 00:48:43 UTC ---
Is vstring going to be promoted to std::string in the *near* future? it doesn't
seem done to me, eg there is no stringstream for it, and it appears to generate
bulkier code. (not scientifically benchmarked)

that said, it doesn't fail this test case, but I haven't checked how its
clear() works, so I'm not sure it has no bug here.