id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc 8371,C++11 once_flag enabled when constexpr is not available,Andrey Semashev,viboes,Boost.Thread should disable C++11 interface for call_once (and once_flag in particular) when the compiler does not support constexpr. Otherwise once_flag construction is not thread safe. This has been brought up in [http://news.gmane.org/find-root.php?group=gmane.comp.lib.boost.devel&article=239023 this] topic.,Bugs,closed,Boost 1.54.0,thread,Boost 1.53.0,Problem,fixed,,