id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
11633	chrono IO V1 may throw bad_cast	Sébastien Barthélémy <barthelemy@…>	viboes	"I had occurences of chrono io throwing bad_cast exceptions, which lead to backtraces like this one:


{{{
    #0  0x00007ffff54fda30 in __cxa_throw () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
    #1  0x00007ffff554f2a2 in std::__throw_bad_cast() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
    #2  0x00007ffff2289bab in std::use_facet<boost::chrono::duration_punct<char> > (__loc=...) at /usr/include/c++/4.8/bits/locale_classes.tcc:137
    #3  0x00007ffff2288c61 in boost::chrono::operator<< <char, std::char_traits<char>, boost::rational<int>, boost::ratio<1l, 1l> > (os=..., d=...) at /home/sbarthelemy/.local/share/qi/toolchains/linux64/boost/include/boost/chrono/io_v1/chrono_io.hpp:210
}}}

I think the attached minimal example reproduces the issue.

Here the compile & run log using boost 1.58
{{{
$ make clean && make test
rm -f src/*.o src/chrono_io
clang++ -std=c++11 -c -g -fPIC -Iinclude -I/usr/include -o src/chrono_io.o src/chrono_io.cc
clang++ -std=c++11 -rdynamic -Lsrc -o src/chrono_io src/chrono_io.o -lboost_chrono -lboost_system -lpthread -L/usr/lib/x86_64-linux-gnu
LD_LIBRARY_PATH=/usr/lib/x86_64-linux-gnu ./src/chrono_io
terminate called after throwing an instance of 'std::bad_cast'
  what():  std::bad_cast
Aborted (core dumped)
Makefile:13: recipe for target 'test' failed
make: *** [test] Error 13
}}}


Here is the code around boost/include/boost/chrono/io_v1/chrono_io.hpp:210
{{{
template <class CharT, class Traits, class Rep, class Period>                  
std::basic_ostream<CharT, Traits>&                                             
operator<<(std::basic_ostream<CharT, Traits>& os, const duration<Rep, Period>& d)
{                                                                              
    typedef duration_punct<CharT> Facet;                                       
    std::locale loc = os.getloc();                                             
    if (!std::has_facet<Facet>(loc))                                           
        os.imbue(std::locale(loc, new Facet));                                 
    const Facet& f = std::use_facet<Facet>(os.getloc()); //<<<<<<< line210, throw here
    return os << d.count() << ' ' << f.template name<Period>(d.count());       
}
}}}

maybe we could avoid calling os.getloc() again at line 210 to avoid the race?"	Support Requests	assigned	To Be Determined	chrono	Boost 1.58.0	Problem