[Bug libstdc++/77704] Data race on std::cype

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77704

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-09-23
            Summary|Data race on std::regex     |Data race on std::cype
     Ever confirmed|0                           |1
           Severity|major                       |normal

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Ugh, we have mutable members in std::ctype<char>

#include <locale>
#include <thread>

int main()
{
  auto& ctype = std::use_facet<std::ctype<char>>(std::locale::classic());
  auto f = [&]{ for (int i = 0; i < 64; ++i) ctype.narrow(i, 'a'); };
  std::thread t1{f};
  std::thread t2{f};
  t1.join();
  t2.join();
}